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Physical and ieical Examination 
of ? 
PAINTS, VARNISHES, 
LACQUERS AND 
COLORS 


By Henry A. GARDNER 


DIRECTOR SCIENTIFIC SECTION, EDUCATIONAL BUREAU 
AMERICAN PAINT AND VARNISH MANUFACTURERS’ ASSOCIATION 


FOURTH EDITION 
OCTOBER, 1927 


7 


Published by 


Institute of Paint and Varnish Research 
2201 New York Avenue, northwest 


Washington, D. C. 


Pe? : Copyright 192 
# By Henry A. Gar 


DEDICATION 


To the Hon. Hersert Hoover 
U.S. Secretary of Commerce 


Under whose helpful engineering guidance and en- 

couragement, many problems have been solved by 

workers in the paint industry, this volume 1s respect- 
fully dedicated. 


Chapter 


I 
II 
Ill 


XI 
XII 


XIII 
XIV 
». O's 
XVI 
XVII 
XVIII 
XIX 


XX 
XXI 
XXII 
XXIII 
XXIV 
XXV 

b. ©. G6 | 
XAVIT 
XXVIII 
XXIX 
XXX 


XXXI 
XXXII 
XXXITI 
XXXIV 
XXX V 
XXXVI 
».0:0.4'8 8 
XXXVITI 
XXXIX 
XL 

XLI 
XLII 
XLIII 
XLIV 


Contents 


Page 
Hiding Power and Brightess.:..... (nese «ei = ae secre 
Consistencecy—Viscosity, Plasticity, Mobility................ 351 
Hardness and Abrasion Resistance. ...... i. se. «+ ssw ere 59 
Gloss Measurements on Paint...... URGE ETS oe ee 89 
Tensile’ Strength. and Elongation. ..:22s..00 «4 see 97 
Film Phickfhess .. 0.06. 40 bab oo opie m oinuel ene tee ine nan < 108 
Drying Time of Films. ... . os e004 p05 gece mnie ete 110 
Temperature and Humidity Control Cabinets...............:; 122 
Specific Gravity Determinations.................. eee mony aly 136 
Determining Coarse Particles in Paint Pigments............. 151 
Particle’ Size of Paint Pigments. ©. UJ: 9 io. 0. oe 165 
Surface Tension and Interfacial Tension of Varnishes and 
Paint. Liquids... 5.295 oe eee TEs be es Gee 174 
Ultraviolet Light Studies on Paint Pigments and Liquids.... 183 
Testing the ‘Light Resistance of Lithopone.................. 193 
Color Systems, Colorimeters and Spectrophotometers........ ZG 
Oil. Absorption. Tests. . . ... «ss a's «cleo mie ale ee ean 
Texture of. ‘Pigments. soe. «. 2. apo 0 oon Shee 276 
. Miscellaneous Physical Testing Devices and Methods........ 281 
Testing White Opaque Pigments for Some Physical Prop- 
erties (Routine: Methods) . 2.2... i sv cans wee 300 
Testing Colors for Tone and: Strength. .7 sane eee eee 305 
Accelerated Testing Cabinets... ....2.. ss «eas ele aunt 309 
Hxposure TestS 2.0.20 ccs ss 6 0m winte Ole bly een eyes enna 541 
Analysis of Paint Oils... 5.05.0. eu yee elena een eee 401 
‘Analysis of VarnisSl i... 5.5 5 6 ooo 6 wise intent iemaiene tae ne 447 
Miscellaneous Tests on Varnishes................ er. oe 465 
Color Standards for Varnishes...... +3 ele ely vig tp es 479 
Analysis of. Mixed Driers. .i.....<0<e...ses a 485 
+Examination and Analysis of Varnish Resins................ 488 
Shellac Analysis: 0.4 ....05 5040085 0 6 © 5 tm pe sie ee inne anne 516 
Bituminous Paints, Varnishes, Cements and Automobile Black 
Baking Enamels’ . 006%) 2-440 6s «s « <9 soles 5385 
Examination of Turpentiné and Mineral Spirits............ 551 
Examination of PWlaxseéed. .. 2... fs. ele eae eiere ie sna een 569 
Examination of Waxes and Polishes... 2... 2.5.05 see 575 
Testing Raw Materials Used in Lacquer Manufacture....... 579 
Analysis of Pyroxylin Coatings.... 2... 4.0 eee ee 595 
Physical Tests on Pyroxylin Lacquers.) .....5 ee 3 612 
Miscellaneous Methods of Testing Materials................ 649 
Analysis of Paints. . o. cic sce oc visie mou aly eereing nen ete 676 
Analysis of White Pigments; ., 00... ics stew) eyes cee 697 
Analysis. of Lead Oxides... 5. .<< ssc os es es oe ee 718 
Analysis-of Reds other than Iron Oxides... ..... 5.59 eee 728 
Analysis of Yellow, Orange, Blue and Green Pigments....... 736 
Analysis of Black Pigments. ..... ss: a's sss sia iis ane . 156 


Analysis. of Iron Oxide Pigments: ........ uc .csinueneeee fio LOO 


PREFACE 


A revision of the previous edition of this book has been 
necessary on account of the rapid advances which have taken 
place in the paint, varnish, and lacquer industry during the 
past few years. An attempt has been made to bring the book 
up to date and to include all modern methods for the physical 
and chemical testing of raw materials and finished products. 
All the latest specifications of the American Society for Test- 
ing Materials are included and given preference over previous 
matter which appeared in the earlier edition and which was 
usd in drawing up many of these specifications. 


There are also included in the back of this book twenty-nine 
specifications of the Federal Specifications Board, which are 
used by various departments of the U. 8S. Government for the 
purchase of painting products. These specifications, which 
have just been printed by the U. S. Government Printing Of-_ 
fice after having been carefully revised, by P. H. Walker of 
the Federal Specifications Board, include several which were 
not present in the previous edition. 


The writer is greatly indebted to the following for aid in 
the preparation of the book: G. G. Sward, A. W. Van Heuck- 
eroth, and P. H. Butler of this laboratory; P. H. Walker, F. 
W. Smithers, H. D. Bruce, L. L. Steele, I. F. Hickson, and 
K. H. Berger of the Bureau of Standards; J. A. Schaeffer, 
fede und. ds. Hi. Barton, F..G. Breyer, P. R. Croll, H. A. 
Nelson, W. R. Fuller, A. F. Brown, H. C. Parks, D. V. Gregory, 
feels, M. Kk. Paul, D; A. Kohr, C. Hall, and other 
members of the industry. 


Washington, D. C. 
October 15, 1927. 


om 


CHAPTER I 
HIDING POWER AND BRIGHTNESS 


When a ray of light falls upon an object, part of 1t is re- 
flected and the balance enters the object. That which enters 
either finally emerges from other faces of the object or after 
multiple internal reflection becomes absorbed. Thus when a 
ray of light falls upon an aggregation of pigment particles 
as in a layer of paint, the light which strikes the eye is com- 
posed of that which is reflected by the surface of the paint 
and that which after multiple reflection within the layers, 
finds its way out. The opacity or hiding power of a paint 
depends therefore upon the amount of ight which is reflected 
before reaching the background. This reflection is propor- 
tional to the total surface and to the refractive index of the 
pigment, or more exactly, the difference in the indices of 
media and pigment. A third factor in the hiding power of 
a paint is the oil absorption of the pigment, in that it deter- 
mines the amount of pigment which may be incorporated into 
a workable paint. | 

If pigments are produced of sufficiently large particle size, 
they, will be somewhat transparent lke a lump of clear glass, 
since all such products allow the light to be transmitted in 
varying amounts. If these lumps are broken down and di- 
vided into a very fine powder, the finely divided particles 
reflect the light in all directions and only a small amount of 
light is transmitted. As a rule, the hiding power increases 
with fineness of division up to a certain point, beyond which 
loss of opacity may be shown.* See page 662. The latter is 
especially true of fume pigments. 


Refractive Index.—The refractive index of a pigment deter- 
mines the amount of light which will be transmitted by 11. 
The higher the refractive index, the greater the reflection and 
consequent hiding power. A layer of white lead will reflect 
more light than a layer of finely ground silica, since the refrac- 
tive index of the lead is higher than the refractive index of the 
silica. As the refractive index of the vehicle approaches that 
of the pigment, opacity diminishes. Consequently when these 


* Larsen, Microscopic Determination of Non-Opaque Minerals, U. 8. Geo- 
logical Survey Bul., 679, p. 13. 


10 Hiding Power and Brightness 


pigments are ground in water, they are less opaque than in 
dry form, because water has a higher refractive index than 
air. When turpentine is used as a binding medium, the pig- 
ments show the same relative differences in hiding power, but 
both are less opaque than when in water, since turpentine 
is more highly refractive than water. When linseed oil is 
used as a medium, still less opacity is shown by the resulting 
paints, as linseed oil has a greater refractive index than tur- 
pentine. The resulting silica paint will now be practically 
transparent, since the refractive index of linseed oil is sub- 
stantially the same as that of the silica. The lead paint, 
however, wiil still be opaque, since white lead has a refractive 
index greater than that of the oil. 


Opacity increases inversely with the amount of oil absorbed 
by the pigment. Thus, for instance, if a white lead and a 
zine oxide pigment should have the same refractive index, 
the white lead pigment might show the greater hiding power, 
since a paint made of white lead usually contains up to 70 
parts of lead and only 30 parts of oil, while one made of 
zinc oxide usually contains only 50 parts of zine oxide. When 
used on the same volume basis, however, the zine oxide paint 
would show superior hiding power because commercial zine 
oxide actually has a greater refractive index than commercial 
white lead. 


The method of determining refractive index which has 
been worked out by Dr. F. E. Wright* of the Carnegie Geo- 
physical Laboratory of Washington, is to immerse the pig- 
ment in media of known refractive indices such, for instance, 
as piperine and antimony triuodide, or mixtures of them. 
Wright’s method of oblique illumination is given below: 


‘‘The index of refraction of a grain embedded in a liquid 
or other body and that of the embedding material can be 
quickly compared by observing their line of contact under 
the microscope and shading a part of the field by placing the 
finger or a card beneath the condenser system, by tilting the 
mirror, or in some other way. A number of devices have 
been recommended for this purpose, and some of the newer 
microscopes have special slides inserted. The observation 
is best made with a low or moderate power objective and 


*Methods of Petrographic Research, Carnegie Inst. Washington, Publ. 
158, 92-95. 


Hiding Power and Brightness Te 


without the condenser lens. With a low-power objective a 
mineral that has a decidedly higher index than the lquid 
will have a dark border toward the shaded side of the field 
and a bright border on the opposite side. If the grain has a 
decidedly lower index of refraction the phenomena are re- 
versed and the bright border is on the shaded side of the field. 
With the moderate-power objective and the condenser lens the 
phenomenon depends on the position of the condenser. If the 
focus of the condenser is above the object the phenomena are 
as stated above; if below the slide, the phenomena are re- 
versed. It is best to check the system used by making the 
test on some known grain; a thin section in which orthoclase, 
quartz, or some other known mineral is in contact with Can- 
ada balsam is good for this purpose. At the same time the 
difference in index of refraction between the grain and liquid 
can be estimated by the relief and the amount of shading 
required to bring out the relief. This method is equally well 
adapted to thin sections and has many advantages over the 
Becke method or the method of central illumination, as it can 
be used with a low-power objective, and by it every grain in 
contact with the Canada balsam ean be compared with balsam 
in avery short time.’’ 


Larsen* has deseribed an niente method as follows: 


‘As the immersion method is ordinarily used nearly all 
fragments are thinner on the edges than in the center, and if 
the fragments differ from the surrounding material in refrac- 
tive index they will act as small imperfect lenses toward a 
beam of nearly parallel light emerging from the condenser. 
If such a lenticular fragment has a higher index of refraction 
than the embedding medium it tends to focus the light above 
its plane, and if the microscope is first focused on the grain 
and then raised above focus the interior of the grain will ap- 
pear more highly illuminated. As the microscope tube is 
raised higher above focus this highly illuminated area con- 
tracts and becomes brighter—a bright line moves into the 
grain. If the tube is lowered below ‘focus the grain appears 
less highly illuminated than the rest of the field and a highly 
illuminated halo surrounds it. Ag the tube is lowered this 
halo moves out from the grain. 


“Tf the grain has a lower index of refraction than the 
embedding medium it will have a virtual focus below its 
plane, the phenomena are reversed, and the grain becomes 


*Larsen. Microscopic Determination of Non-Opaque Minerals, U. S. 
Geological Survey Bul., 679, p. 14. 


12 Hiding Power and Brightness 


centrally illuminated as the microscope tube is lowered below 
focus. 

‘‘In practice the test is best made with an objective of 
medium or high power—one with 8-millimeter focus gives 
good results. The condenser may be in or out. The con- 
denser system may be lowered or the lower diaphragm closed. 
The most suitable arrangement for a particular microscope 
and. lens system can best be found by testing it with grains 
embedded in media of known indices of refraction. 


‘‘Immersion media should be nearly colorless, chemically 
stable, and without disagreeable odor or other objectionable 
properties. They should not dissolve or react with the min- 
eral to be immersed. Low volatility and for many purposes 
a moderate though not too great viscosity are desirable. Each 
liquid should be miscible with the liquids whose indices of 
refraction are above and below it, and two liquids that are 
to be mixed should have approximately the same rate of vola- 
tilization, as otherwise the mixture may change rapidly. The 
index of refraction should not vary too greatly with changes 
of temperature. A low dispersion is desirable for accurate 
work, but a rather strong dispersion facilitates rapid deter- 
mination.”’ 


There are presented below results on some pigmentary sub- 
stances as given by Merwin or in the International Critical 
Tables: 


REFRACTIVE INDICES OF SOME WHITE PIGMENTS. 


Refractive 

Pigment Index Authority 
Basic Carbonate White Lead. 26.50 140 oss 1.94—2.09 Merwin* 
Basic Sulphate: White: Lead... i.c. sess eee 1.93 Merwin* 
Lath Oponen.. Ses se wee wale edee eh Reh Seen wa bee 1.84 Merwin* 
Fine OxeIde (AN) so... clcciee cee oe ca oe ee 2.02 Merwin* 
Zine Sulhde © (ZS )) ac delet amcsoconc le Go ain er eee 2.37 Merwin* 
Titanium Oxide TiO, ees eee joa lal gies eee 2.76 | ee We bf 
Barytes:(.BaS0;) soa 25 ahs on <8 oe Sale cae ie eee 1.64 Merwin 
OCaletiim (Sulfate suc heses uke so courte oe ae 1.59 Dae Se i 
Aine  Bulnge cog 4 eee Oe ce ote vente ey cee ee 2.37 WeOe B, 
Antimony “Ox: «civ aise ans ecue a apne le a ee 2.09-2.29 be BP 
Siliea -StO, quartie ssi. cy eins Sela eas oh 155 ME 


It must be remembered that most of the non-opaque pig- 
ments are crystalline and usually possess different refractive 
* Merwin, see page 153, this book. 
yMerwin gives results on Lithopone ranging from 1.70 to 2.25, the 


latter constituting 1%. These tests made previous to advent of modern 


Lithopone. 
tI. C. T.—International Critical Tables, Vol. I. 


) 
i 
| 
| 


Hiding Power and Brightness 13 


indices along the different crystal axes. The values given in 
the above table are mean values for all directions. 

Hiding Power Instruments.—Probably the most accurate 
device for determining the hiding power of liquid paints is 
that devised by Dr. Pfund, and described on page 14. This 
instrument has found quite a wide application in the trade. 
An apparatus was designed along a somewhat similar princi- 
ple by the present writer, but giving direct readings without 
manipulations of the clear glass cover top. Itis free from the 
possible criticism of pigment accumulation at localized spots, 
due to working back and forth of the cover glass. The base of 
the apparatus (10 cm. in length and 214 em. wide) is of opaque 
white glass or of opaque black glass, according to whether 
white or colored paints are to be tested. At the end of the 
base is a metal piece made of German silver, permanently 
cemented on. This metal piece is 1 mm. thick. The surface 
of the glass base is divided into 10 equal parts, thus making 
the readings between each part 1/10 mm. A broad longitudi- 
nal etched line passes down the middle of the glass base. The 
liquid paint to be examined is poured on the base, and the 
clear glass cover plate placed on the apparatus. The visibil- 
ity of the longitudinal line disappears at a point between any 
two of the cross lines, which can be estimated in tenths of a 
division. The thickness of the paint at the point of hiding 
may therefore be directly read off in hundredths of a milli- 
meter. Further experiments are being made to improve the 
apparatus. 


For determining the relative hiding power of lquid and 
also dry paint films, the writer has devised a rather simple 
method which uses a sheet of bond paper upon which squares 
of black, dark gray, light gray, and other graduated tints of 
gray are printed with wood blocks. These are lettered from 
A to H. After the sheets are furnished by the printer, they 
are kept in stock in the laboratory, and a brush coat of any 
experimental paint is applied in comparison with a standard 
product. While possibly subject to criticism from several 
angles, this method has been found satisfactory for general 
comparative work. 


Other sheets of paper are printed with blocks of red, blue, 
green and yellow. They are then sized and varnished to deter- 


14 Hiding Power and Brightness 
ees 


S55 Y . . 
mine durability of the varnish over various colors. The use 
of sheet tin in place of paper has been suggested as a base 
for these test specimens. 


Figure 1 


Shaded paper for comparing Color block paper for varnish 
hiding power of paints. liquids. 


The Pfund Cry ptometer.—This is an ‘‘absolute’’ instrument 
by means of which it is possible to determine the hiding — 
power of a paint and of a pigment. 


Hiding power may be defined as that property of a paint 
which enables it to obliterate beyond recognition any back- 
ground upon which it may be spread. Since the color of the 
background affects the numerical value of the hiding power, a 


Hiding Power and Brightness 15 


black background is chosen for white paints and, conversely, 
a white background for black paints. In the case of colored 
and gray paints, it will be necessary to carry out measure- 
ments for both types of background. 


The idea underlying the construction of the cryptometer is 
this: granting that an infinitely thick layer of paint will hide 
a given background completely, it 1s sought to find the least 
thickness of paint which will be as effective in hiding as is the 
infinitely thick laver. 


The form given the instrument is shown in Fig. 2. Here, A 
is a plate of black glass 14 x 5 < .6 cm. whose upper surface 
is optically flat. A transverse groove, B, about 2 mm. deep 
and 1 cm. wide, is cut in the upper surface and a milimeter 
scale is etched, as shown in the drawing. Resting upon plate 
A is plate C (7 X 3.5 X .6 em.), whose lower surface is like- 
wise optically flat. A strip of thin steel, D, 0.45 mm. thick, is 
attached to C, so that a wedge-shaped layer of white paint 
may be formed between the plates. This wedge terminates 
abruptly at the ‘‘infinitely thick’’ layer, B, and, so long as the 
hiding is not complete, the line of demarcation is visible. By. 
sliding the wedge to the left it is finally impossible to see the 
edge. From a knowledge of the angle of the wedge and the 

- reading on the seale, it is possible to calculate the thickness 
of this critical layer lying immediately above the edge B. 
Now, in advancing the plate C until the line of demarcation 
ean no longer be seen, we have overdone it, so to speak. To 
correct this, we must reverse the motion of the wedge until 
the edge can just be distinguished over its entire length. The 
mean value of the reading corresponding, respectively, to 
disappearance and appearance of the edge, yields the desired 
result. Since the fading away and reappearance is so gradual, 
due to the fact that the least preceptible increment of intensity 
which the human eye can detect is 1 to 2 per cent (Fechner’s 
Law), it is clear that no high degree of precision is attainable 
by this method. By taking ten pairs of readings it is found 

~that the average deviation from the mean is about 95 per cent. 


The hiding power of a paint may be obtained at once from a 
knowledge of the wedge-constant A (increase in thickness of 
paint film per unit linear advance along etched scale) and of 
l the wedge- reading at complete Rae Lumping together 
the various numerical constants and recalling that / is meas- 


16 Hiding Power and Brightness 


ured in milimeters, it is possible to express the hiding power 
(H-P) of a paint by the simple relation: 
40.7 


Hes square feet per gallon. 


Kl 
A sharp distinction must be made between the hiding power 
of a pigment and that of a paint. Not only are these quantities 
expressed in different units, but they are not necessarily 
related in the sense that a pigment of great hiding power 
necessarily produces a paint of correspondingly great hiding 
power. Taking up first the hiding power of pigments, let us 


FIGURE 2 


Diagram of Pfund Cryptometer. 


consider an intimate mixture of x grs. of a white pigment and 
y grs. of colorless (or very pale) linseed oil. This mixture is 
tested in the cryptometer and the critical thickness producing 
complete hiding is found. Let 

¢t thickness of critical layer (in ems.). 

b—=numbers of grs. of pigment in a disc of 1 em? base and thickness t. 
Then, if b grs. pigment hide 1 sq. cm., we find the number of 
sq. cm. A covered and hidden by 1 gr. of pigment from the 
relation 

ide as Pagina ty | jee 
b 

Since the hiding power is better the thinner the layer, 1. e., 
smaller than b, we may define the hiding power of a pigment 
as the reciprocal of the number of grs. of pigment mixed with 
colorless linseed oil to painting consistency, which are neces- 


EE 


li alt! 


Hiding Power and Brightness 17 


sary to hide a black, non-absorbent area 1 sq. cm. This is 
numerically equal to the number of square centimeters covered 
and hidden by 1 gr. of pigment. Hiding powers of pigments 
will, therefore, be expressed in terms of sq. cm. per gr. The 
mode of calculating the hiding power of pigment and paint 
may, perhaps, best be illustrated by means of an actual deter- 
mination: 


Paint: 
Basie Carbonate White Lead—72% by wt.—Density 6.81 Specific Vol. 0.147 
Linseed Oil —28% by wt.—Density 0.92 Specific Vol. 1.08 


Cryptometer constant K — 0.0073 
Cryptometer reading at complete hiding: 125 mm. 


72 X 147 = 10.6 
28 X 1.08 = 30.3 


40.9 c.c. paint contain 72 grs. pigment 
40.9 

—= 0.567 ¢.c. contain 1 gr. pigment 
(2 


0.567 0.567 
91.1 area covered by 1 gr. pigment in. cm? 
Kt 0.0073 x 25 


-°. H-P (pigment) = 31.1 cm? per er. 
40.7 
H-P (paint) = 


— 223 sq. ft. per gal. 
KX1 
These illustrations will suffice to show how calculations are 
carried out. A table of hiding powers, determined by this 


method, is presented elsewhere (see page 21). 


Lhe Pfund Colorimeter for Nearly White Surfaces.—In 
view of the circumstances that ordinary colorimeters are en- 
tirely too intensive and that visual estimates depend upon the 
character of the comparison surface, the present instrument 
was devised to yield quantitative colorimetric data for nearly 
white surfaces. 


The idea underlying the construction is as follows: If we 
allow white light to fall upon a surface that is faintly greenish, 
the light reflected diffusely will contain a slight excess of 
green; if now this light be allowed to suffer reflection from a 
second surface, identical with the first, the light thus twice 
reflected will contain a greater percentage excess of green than 
before. By allowing, similarly, a third and a fourth reflection 
to take place, the accentuation of the green tint continues and 
finally becomes so pronounced that it may be measured readily. 


18 Hiding Power and Brightness 


This is the method of ‘‘multiple reflections,’’ according to 
which only truly non-selective (white or grey) surfaces leave 
the character of multiple reflected light unmodified. Any 
outstanding tint, however, is accentuated. 


The apparatus as actually constructed is shown in Fig. 3. 
Here LZ is a powerful Mazda C lamp which illuminates the 
outer portion of the circular disk A, whose upper surface is 
covered with the material to be studied. he light, diffusely 
reflected, illuminates the lower (similarly coated) surface of 


| 


---|----4->-------4--0> 


| 


FIGURE 3 


Diagrammatie Representation of Pfund Colorimeter. 


the disk B which, in turn, illuminates the central portion of 
the disk 4. The light, after multiple reflections, passes: up- 
ward through a central opening in B and is reflected horizon- 
tally by means of the photometer cube P. Another beam of 
light leaving L is reflected from a disk of clear optical glass 
G, roughly ground on both sides. (Without going into de- 
tails it may be stated that the most painstaking tests have 
shown that such a plate reflects visible radiations non-selec- 
tively.) This light passes through the tube 7 and fills the 
upper half of the field of view of the photometer cube which 
has a horizontal line of demarcation and which is viewed 
through a simple eye-piece yielding a linear magnification of 


See: ee ee eae ee 


Hiding Power and Brightness 19 


2.0 The intensity of this beam is varied by rotating the disk 
G about a horizontal axis. A pointer, attached to the rod 
bearing disk G, moves over a graduated scale which has been 
calibrated in terms of coefficients of diffuse reflections. The 
true values of such coefficients are first determined for a series 
of grey pastes (zine oxide, glycerine, bone-black) of varying 
brightness by means of an absolute reflectometer. The colori- 
meter plates are then covered with these same pastes and 
scale-readings at photometric balance are recorded. 


As a result of multiple reflections, the difference in scale 
reading corresponding to surfaces of slightly different bright- 
ness 1s about four times as great as it would have been had but 
a single reflection been used. 


While this colorimeter lends itself admirably to the methods 
of monochromatic colorimetry, it has been found by actual 
experience that useful results are obtained more simply 
through the use of color-screens. Accordingly, color screens 
of dominant hue 480 wu (blue), 540 wu (green) and 605 wu 
(red) are successively placed in the eye-piece tube at S and 
psotometric balances are established. The scale-readings thus 
obtained are then evaluated into reflection coefficients by refer-. 
ring to the calibration curve. This is essentially a spectro- 
photometric procedure. 

The final results are presented in the form of curves where 
abscissx represent wave-lengths of the color-screens and ordi. 
nates, reflection coefficients. A characteristic series of such 
curves applying to modern paint pigments will be presented 
elsewhere (see page 24). 


Hiding Power and Brightness of Pugments.—The writer se- 
cured from manufacturers, a series of white pigments repre- 
sentative of those produced in commercial quantities at the 
present time, and widely used in the industry. Portions of 
these pigments were rubbed up with glycerine and careful 
measurements of their brightness made by Pfund with the 
following result: 


20 Hiding Power and Brightness 


TABLE 1.—Brightness of Various Pigments 


Coefficient of Diffuse Re- 
flection (MgO =99.4%) 
No. Pigment Pigment in Glycerin 


Blue Green Red 
A—480uu| A—560 | A—630 


| | | 


1 | Basic Sulfate—White Lead.................. 81.2 87.6 89.3 
2 | Basic Carbonate—White Lead...............| 79.8 | 82.7 | 4.7 
3’) Bleetrolytie Winte Lead. Vue 86.4 | 88.0 | 89.0 
~ 4 | Old Process Lithopone.@ 2a rn 84.7 | 87.2 | 88.4 
5 | Leaded Zine (35% Lead Sulfate)......... | 784-1) G00 homueone 
are Modern Process G. 8. Lithopone..........2.. 87.2 | 87.6 87.8 
woe Modern Process K. L. Lithopone............. 88.9 | 88.2 88.2 
“g | Antimonious Oxide. .........1.... 1, ele 86.4 | 89.0 | 90.1 
aie Titanox (High oil absorption)... 4. 83.1 87.2 89.5 
Se Titanox (Low oil absorption). 22... .35 sae eeee 86.8 89.0 | 90.1 
“12, | Zine Oxide (French process)...1.... Aaa 88.2 | 88.9 | 89.5 
ae aN Oxide (American Process)............... 82.7 86.0 86.8 
vies Modern Process A. Lithopone................ 88.9 87.8 88.0 
Ce Modern Process S. Lithopone (Regular)....... 86.6 88.7 89.7 
ee Madera Procass S. Lithopone (Special)........ a8 48 87.8 87.4 
oat eMadert Process G. S. Lithopone.....:........ Ses ane Vague 88.0. 
ae Modern Process A. Bk Label Lithopone....... 88.7 88.0 88.2 
me Modern Process A. BI Label Lithopone........ 88.7 ee pp 4 
ee Modern Process P. L. R. Lithopone........... 80.5 | 88.4 | 87.8 


Se ean eee cl n eee oe Set ae a BE 


Hiding Power and Brightness 21 


TABLE 2.—Hiding Power of Pigment-Oil Mixtures, Each Containing 50 Per Cent 
Pigment and 50 Per Cent Linseed Oil by Weight 


Paint Pigment Hiding Power 
No. Sq. Ft. per Gal. 
1 mpsie cuipnate--White Lead.................2 0.005. 116 
a Basic Carbonate—White Lead...................... eg ate 
3 Retr VO VV LG LOA). eke cee eee ee 
aa Old Process arohe. 6 it cg ey mt ee 145 Baer 
ae Teaded Zinc (55% Lead Sulphate)...........:....... hh O00 as 
6 Modern Process G. 8. Lithopone is Beer een eae) sian Ailes 0G 
7 Modern Process K. L. Sa ee See NE dee ue Boon ape 
8 Antimonious Oxide........ ee is Seer ie ee theres ee 193 Ms 
0%. Titanox (High oil ee Be REE rd cra iG Suter ee oS ae 
11 Titanox (Low oil absorption). . See cle es DARN oe 
{2 aMe Oxide feTiGl PTOCeSS) 6... ke oe cee ee Ny sons 
‘ 13 mimew) side (American process) .... 2.0.0.0. 00. 5.0000 e een ne 
14 Modern Process A. Lithopone............. Oe ees. 55200 Pie 


Another series of these pigments was ground in a mill with 
refined linseed oil, on the basis of 50 parts by weight of pig- 
ment to 50 parts by weight of oil. These gave the following 
hiding power results in the writer’s laboratory. See Table 2. 


FOOTNOTE: 
Tests with the Pfund cryptometer on a large number of samples of each pigment examined by 
R. L. Hallett gave average general results as follows: 


Hiding Power of White Pigments 


For complete hiding: 


Sq. cm. Sao tn Lbs. per | Hid. Pow. | Hid. Pow. Tint. 

per gram per lb. 100 sq. ft. weight volume Power 
ELE MUCACAt. wits diced sss + 40 19.5 Leal 100 100 100 
Basic lead sulphate......... 30 Wate 6.8 75 1 85 
"PTET WOE. Ag aga a 80 39.0 2.6 200 128 350 
Zine oxide(American process) 46 92.4 4.5 116 96 170 
NHI GWOMG 8p clecivis isis sincere. ee 50 24.4 4.1 125 80 200 


It should be pointed out, however, that pigments of great 
brilliancy, such as zinc oxide and basic sulphate-white lead, 


22 Hiding Power and Brightness 
a 
may show relatively low hiding power in their untinted condi- 4 
tion. When slightly tinted with colors to match the color of 
leaded zinc or basic carbonate-white lead, they may show as 
great or even greater hiding power than such pigments.* 
Hiding power and brilliancy should, therefore, always be con- 
sidered together. 

A third series was ground, using only sufficient oil to give 
consistency for brushing. The readings on the cryptometer 
are shown in table. 


G A R 


a 
§ 
w 
3 


& $ 


7 


) 
o 
1°) 


| 


Reflection Coefficient (Brightness ) 
@ 
w 


© Untinted 
© Blacked 
@Blued 


| 
‘650 


G R 
Wave-Lengths 


| 


© 
wo 
wn 
° 


FIGURE 4 
Curves showing the effect of adding Carbon Black and Ultra- 


marine Blue to French Process Zine Oxide ground in refined 
Linseed Oil. 


* See J. Franklin Inst., Nov. 1919, p. 679. Also J. A. Calbeck’s paper, “An 
Application of the Pfund Cryptometer,” etce., Proc. Amer. Soe, Test. Mater., 
1922. 


Hiding Power and Brightness 


23 


TABLE 3.—Hiding Power of Pigment-Oil Mixtures Containing Different 


Paint 


13 


14 


Amounts of Oil 


Percentage By Hiding Power 
Weight As 
Determined By |_____ ie es 
Pigment Analysis 
hn, Se ee Pigment Paint 
Sq. Cm. per Gr.) Sq. Ft. per Gal. 
Pigment} Oil 
Basic Sulphate White 
Lalor ha tee a a 69.7 30.3 25 159 
Basic Carbonate White Le s ae 
Neer Oe iy 70.4 29.6 36 242 
Electrolytic White ee, ee 
Or CS ee iieo 28.7 32 212 
Old Process Lithopone | 58.4 41.6 59 ZZ 
Leaded Zinc (85% Lead a a 
i be] N20 or ee hae aaa 63.6 36.4 49 252 
Modern Process G. 8. ms a 
PEMOPONG Se... | 61.6 38 .4 57 252 
Modern Process K. L. ae 
He HOPONE Aa Ss. - 58.4 41.6 58 eon 
Antimonious Oxide...) 64.5 35.5 44 232 ae 
Titanox (High oil ab- 
BORDEN) 6 55.2. 1. 60.1 39.9 69 293 
Titanox (Low oil ab- 
OED RON) cen W506. x0" 66.3 33.7 OF 293 
Zinc Oxide, French 
POCCHS das ss. > 50.2 49.8 A4 142 
Zine Oxide, American 
Procesgries. fee. 46.4 53.6 bo 155 
Modern Process A. 
bithopone ...2.,.:. 59.1 40.9 54 212 


* Note low luminosity of -this sample in Table 1 which acounts for greater 
hiding power as compared to other lead. 


24 Hiding Power and Brightness 


ee w 
°o 
o 
wn 
nn 


3 
WINE 


ANAT 
SEER 


= 
\S 
» 


i 
MK 


| 
. 


aa 
; 
M 


wai 
aii 
Nt 


uw 
4) 
| 


N 
NI 


Reflection Coefficient (Brightness) 


KAW 


ye 


B G 
Wave-Lengths 


22) 
2) 


o 
on 
oO 


FIGURE 5 


Curves showing the brightness of commercial opaque pig- 
ments ground in glycerine. Degree of whiteness is indicated 
by the approach to a straight horizontal line. 


Hallett Hiding Meter.—An apparatus devised by R. L. 
Hallett for measuring the hiding power of dry films of paint 
was originally described in the 1920 Proceedings of the Amer- 
ican Society for Testing Materials. It has been used in Hal- 
lett’s laboratory for several years, with apparently satisfac- 
tory results. A brief description of the apparatus is given 
below, but the original communication should be read for a 
detailed description. The instrument can be modified for 
use upon different parts of a painted surface, and variations 
in hiding power over knots and dark spots in lumber ean be 
determined. 


Hiding Power and Brightness 25 
a A 
‘“The instrument is shown in Fig. 6, and consists of a 
regular microscopic frame with a long tube fitted with a plain 
ground-glass objective, and having simply a small circular 
opening for the ocular. The principles involved are not new, 
but the application seems to be novel, as we do not know of 
these principles having been previously used for this purpose. 
If a piece of ground glass, or other more or less transparent 
material which has the property of highly diffusing or dispers- 
ing the rays of light which pass through it, be placed in direct 
contact with a surface having two colors or two shades of the 
same color, and if the surface be viewed through the glass, 
the two colored portions and the line between them will be 
perfectly clear and distinct. We have found that as the 
ground glass is withdrawn from the surface, the line between 
the colored portions immediately becomes blurred and indis- 
tinct, and the colored portions themselves also become blurred 
and tend to blend into each other. This effect is increased as 
the ground glass is further withdrawn until a point is reached 
where the entire field becomes blurred and blended, so that it 
appears to be of uniform color, and there is no distinction 
between the two colored portions. | 


FIGURE 6 


Hallett Hiding Power Meter. 


26 Hiding Power and Brightness 


‘“We have also found that if one of the colors be partially 
obscured, as by having applied over it a semi-opaque coat of a 
paint of the other color, and the contact and withdrawal of the 
eround glass be repeated, the two colored portions of the field 
will blend and the field will appear to become uniform when 
the ground glass is withdrawn to a much shorter distance 
from the surface than was the case where the full original 
colors were used. The application of the coat of paint over 
the surface partially hides the portion of the surface which 
is not the same color as the paint, and the degree of hiding 
may be measured by the distance through which the ground 
glass must be withdrawn to blend the field. The portion of the 
surface which has the same color as the paint of course re- 
mains unchanged in color and offers the same basis for com- 
parison. The decrease in sharpness of the image and the 
blending of the field, as the ground glass is withdrawn, is due 
to the diffusion of the light. The colored surfaces diffuse 
the light equally in all directions, but when the ground glass 
is in contact with the surface, the diffusion takes place above 
the glass and the eye sees the two colored portions distinctly. 
As the ground glass is removed further and further from the ~ 
surface, the diffused rays from the two colored portions of the 
surface spread in all directions so that the rays from each 
color tend to mingle with those from the other color and strike 
the ground glass mixed together. This results in a gradual — 
blending of the two colors over the entire field. The ground ~ 
glass finally reaches a point where the field seems to become ~ 
blended into one uniform color. As the blending is dependent — 
on the diffusion of the rays, it must be proportional to the — 
square of the distance between the ground glass and the sur- — 
face viewed, as diffusion varies directly with the square of © 
the distance. Theoretically, there would never be a perfect — 
blend, as each part of the field would always transmit to the 
eye more rays of its original color than of the color of the — 
adjacent part whose rays are diffused on to it. It is, there- — 
fore, apparent that the theoretical distance at which the field 
would become perfectly blended, would be infinity.’’ | 


Hiding Power and Brightness 27 


Working with a number of white pigments ground in linseed 
oil upon the volume basis, some interesting results were ob- 
tained by Hallett, as shown below. 


PIGMENT. Hipine Power, 
RE ire tee ae yee ee cli eek SEO erie 100 
BM AL eos oon Sei ceva ove cicccn...., 82 
SL A 167 
EE ee. ns 2 oo ook eve van eee. eee 103 
as org oy Ss sole es de hho bec Oune cece ce, 85 
eISSN 1 
TS Rn 5 
ONS os a 
OE Re 4 
ee de soe oe eee Ohne heen. 1 


White lead was taken as the standard and arbitrarily given 
a hiding power of 100. 


Tinting Power vs. Hiding Power.—In a subsequent paper 
entitled ‘“The Hiding Power of Pigments,’’* Hallett gives the 
following table: 


TABLE 4 
RELATIVE RELATIVE RELATIVE 
HIDING HIDING HIDING HIDING TINTING 
POWER, POWER, POWER, POWER, POWER, 


SQ. FT. SQ. CM. WEIGHT VOLUME WEIGHT 
PIGMENT PER LB. PER G. BASIS BASIS BASIS 
No. 1. Carbonate White Lead.. 20 40 100 100 100 
No: 2. Basic Lead Sulfate...... 15 30 fee eee 85 
Os SILATIOX. sc... ss os Peevs ki 40 80 200 128 350 
eee ISIIO  .. se te c e s 2s 46 195 96 170 
arr LAtMOpoOnes.... 0.0. ..5. 25 50 125 SO 200 


He states that the tinting power and hiding power of pig- 
ments are directly related, and that the hiding power is 
directly proportional to the tinting power for pigments which 
have the same color and brightness. In this connection, there 
is presented on page 303 the method adopted for determining 
the tinting power of pigments by L. E. Barton, together with 
a table. 


Martens Photometer for Hiding Tests.;—This is an in- 
strument which measures the contrast in brightness offered 
by two portions of a field of view. If a light colored paint be 
spread upon a background which is divided into a white por- 
tion and a black portion, there is a certain thickness at which 
the differential brightness of the background is eliminated. 
This may be called the hiding thickness. Ina determination, 
a background divided into a white and a black portion is 


*A.S.T.M., Vol. 26, Part II, 1926. 
TH. D. Bruce, Tech. Paper, No. 306, U. S. Bur. of Standards. 


28 Hiding Power and Brightness 
ee ci es 
coated with the paint, and when dry is placed with the divid- 
ing line in the field of view. On looking into the photometer, 
a diviiea field is seen. The two halves of the field are matched 
by rotating a Nicol prism and their relative brightness caleu- 
lated as a function of the angles of rotation. The apparatus 
is shown in Fig. 7 

The contrast ratio of the two halves of the field is first 
calculated from the angles of rotation mentioned above. ‘Then, 
by means of the equation 


L 
H.T. = va|— cae! 
b 


where a is the thickness of the film under observation and b 
the contrast ratio, H.T. the thickness of film necessary to make 
the black side of the plate 98 per cent. as bright as the white 
side, is determined. 

These hiding thickness values are the thicknesses of the 
dried film that will be required to hid ‘‘completely.’’ From 
these values, the hiding powers in square feet per gallon may 
be obtained, provided a knowledge of the volume percentage 
of the non- volatile portion is known. This may be calculated 
from the specific gravity of the paint, specifie gravity of the 
volatile constituent, and the weight percentage of volatile con- 
stituent. For example, the following illustration is given: 

a—sp. gr. of paint —1.48 

b=sp. gr. of volatile constituent (turpentine) = 0.867 

c—wt. percentage of volatile constituent in paint =10 


xX volume percentage of volatile constituent in paint 
H.T. = hiding thickness = 0.0706 mm. 


ac 
SS eee 
b 
100 — X = 100 — 16.8 = 83.2% non-volatile by volume 
Then the hiding power (H.P.) in square feet per gallon 
may be read from Table I in Technologie Paper No. 306, or 
calculated from the formula: 


0.4075 (volume per cent of non-volatile) 
H.T. 


HP. = 
0.4075 x 88.2 
ae eo TOS 


—= 480 sq. ft. per 1 gallon 


Hiding Power Comparisons.—There is given below some 
hiding power readings expressed in square feet per gallon 
as determined (in May 1927) upon a number of paints with 


Hiding Power and Brightness 29 


FIGURE 7 
Apparatus for Measuring the Hiding Power of Paints. 


The upper telescopic portion is the Martens photometer, while the lower 
spherical shaped portion is the illumination chamber designed and built at 
the U. S. Bureau of Standards. 


NOTE—For full construction and theory of the Marten’s photometer, 
consult the original paper by Marten’s. Physikal Zeitschrift (Leipzig) i, p. 
299; 1900. 


the Pfund Cryptometer and with the Martens Photometer. It 
will be noted that the results on the Pfund Cryptometer are 
usually somewhat higher than those obtained upon the other 
type of instrument. Since the use of the Pfund Cryptometer 
is extremely simple and rapid, this instrument has been pre- 
ferred for the determination of hiding power at this labora- 
tory. 


30 Hiding Power and Brightness 


Hiding Power on Hiding Power (Bur. of 
Pfund Cryptometer, Standards Method) 


FORMULA sq. ft. per gal. to sq. ft. per gal. to 
hide a black surface hide black surface 
A. Pure Titanium 
Oxide 100 55,5 480 
B. Calcium Titanox 100 339 408 
C, Barium Titanox 100 339 322 
Dw “Ditanox 80 
Zinc Oxide 20 305 234 
BE. Trtanox 70 
Zinc Oxide 30 290 208 
FEF. Titanox 50 
Zinc Oxide 50 ZTE 200 
G. Titanox 80 
Corroded Lead 20 290 B&W 
H..- Titanor 60 3 
Corroded Lead 20 265 223 
Zinc Oxide 20 


Formula A has 50% Pigment and 50% Liquid. Formulas B to M all 
have 60 pigment and 40 liquid. The liquid in each is the same, namely, raw 
linseed oil 60%, heavy bodied oil 20%, turpentine and drier 20%. 


Hiding Power on Hiding Power (Bur. of 


Pfund Cryptometer, Standards Method) 
FORMULA sq. ft. per gal. to sq. ft. per gal. to 
hide a black surface hide black surface 
To. (LItanox 50 
Corroded Lead 20 Tees 188 
Zinc Oxide 30 
Ke Seo 30 
Corroded Lead 20 244 180 
Zinc Oxide 50 
L. Lehigh Leaded Zinc 70 259 141 
Lithopone 30 
M. Lehigh Leaded Zinc 70 305 207 
Titanox 30 “3 


AA. Tung Oil Spar Varnish 
containing 40% Pure 
Titanium Oxide 382 346 


BB. Tung Oil Spar Varnish 
containing 40% Bar- 
ium Titanox 234 yids 


CC. Tung Oil Spar Varnish 
containing 40% Cal- 
cium Titanox 254 208 


DD. Tung Oil Spar Varnish 

containing 40% Litho- 

pone 174 147 
EE. Tung Oil Spar Varnish 


containing 40% Basic 
Carbonate White Lead 122 84 


CHAPTER II 
“CONSISTENCY 
VISCOSITY—PLASTICITY—MOBPILITY 


In this chapter methods are presented for determining the 
consistency of oils, varnishes, paints, lacquers and similar 
products. There is also included a brief description of differ- 
ent types of apparatus used, and tables for the conversion 
of the readings of one type of instrument to another. In 
order to understand what is meant by the various terms em- 
ployed in this chapter, the following definitions are given: 

(a) The consistency of a product is its resistance to defor- 
mation or flow. This resistance may be due to viscosity or to 
plasticity. 

(b) The viscosity of a product is its resistance to deforma- 
tion or flow when deformation or flow is directly proportional 
to the force exerted at all times. 

For example, if a tube tapered at one end to a small orifice 
is filled with varnish, we note that no matter what the con- 
sistency of the varnish may be, it will flow from the tube, with- 
out any regard to the hydrostatic head or any other factor of » 
pressure. | 

(c) The plasticity of a product is its resistance to deforma- 
tion or flow when a certain initial finite force is necessary to 
overcome the internal friction and cause the product to flow. 

For example, if the same tube is filled with a heavily pig- 
-mented paint, such as an interior flat white, and if the hydro- 
static head of the paint becomes very low the paint will not 
flow out of the orifice. The pressure has fallen below the 
initial pressure required to cause a plastic substance to flow. 
This initial pressure is called by some authors the ‘‘yield 
value.’’ 

(d) A substance is said to have a viscosity of one poise 
when a force of one dyne is required to move a surface of one 
square em. at the speed of one centimeter per second, relative 
to another plane surface separated from it by a layer one 
centimeter thick. The poise is the measurement of absolute 
viscosity. 


Instruments for Measuring Viscosity—All viscometers in 
use may be classed under the four following types of: air 
bubble—falling weight—torsion—or efflux. 


2 Consistency 


(1) Air Bubble Type (Gardner-Holdt Standards ).—Small : 


vials or tubes closed at one end and standardized as to internal 
dimensions, are filled with a liquid, the absolute viscosity of 


which has previously been determined, and a cork inserted ~ 


so as to leave a small air space. A number of these liquids 
of varying viscosity are put up this way and comprise a set. 
When the tubes are inverted, the times required for the bub- 


bles to arise are directly proportional to the viscosities of the ~ 


liquids in the tubes. 


In a determination of viscosity, an empty standardized tube 
is filled with the material to be tested, and the air space ad- 
justed to the size in the comparison tubes. The rise of the 
bubble in the tube is then compared with ete on the standard 
set* 


Below are given the data from the Gardner-Holdt Vis- 
cometer tables, describing the method of use and giving the 
range of viscosity in poises: 

Before making the test a tube containing a sample of the 
varnish to be tested and the case of standard tubes should be 
placed together for a sufficient period to bring them to the 
same temperature. The test should preferably be made at 
25° C. (77° F.) on account of the difference in the temperature 
coefficients of viscosity of mineral oils and of varnish. 


The air bubble in the sample tube should be approximately 
the same size as that in the standard tubes. When operating 
the standards, the case should be held in an upright position 
with the red sealed corks at the bottom, so that the bubbles 


will be at the glass end. The case should then be inverted — 
quickly and the sample compared to locate the standard tube ~ 


giving approximately the same bubble test. 


The standard tubes and the empty tubes supplied with this . 
case have an approximate inside diameter of 10.75 mm. It is ~ 
very important that these tubes should be of very nearly the 3 


same diameter, the allowable variation being about .1 mm. 
Tubes not in accordance with this specification cannot be used. 


*In measuring viscosity of varnishes with Gardner-Holdt tubes, Gregory — 
has used the standard tubes firmly fastened in a holding rack, with sufficient — 
space between the tubes for test samples. By the use of this holding rack — 
the tubes are subject to less breakage and gumming up with varnish, and any ~ 


variations in temperature effects due to the handling of the tubes is elimi- 


nated. The rack is supported on a solid foundation and the whole set can be — 


inverted at once. 


A a O00) 
A 0.65 
MEER Sects: 4x 0.85 
Me Feta! «sh 1.00 
1D) » 1.25 


K 


Consistency 
a 


There is given below the approximate absolute viscosities of 
the liquids used in the standard tubes: 


FIGURE § 


.. 1.40 eA Seen 
pea s SE Mk OD Li Whee twists 3's 
Mates ees ee OO dC ae ee 
ane 2.25 INGe ap esa hate 
BRO tuning AAEM) PAP es cee Gila 


Doolittle Viscometer. 


af 


Lies I.) 
.. 4.00 
.. 4.35 
ieee els eck 
Piemintiwiete NU) 


. 0.00 


34 Consistency 
Oe ee 

(2) Falling Weight Type—Viscosity is sometimes meas- 
ured by dropping a steel ball in a vessel containing the fluid 
and timing the fall between two elevations. This method prob- 
ably gives a fairly accurate measure of viscosity for very vis- 
cous liquids. It is used to a great extent in the lacquer indus- 
try. When a nitro-cotton is referred to as a % second nitro- 
cotton, it is meant that when the cotton is made up in solution 
according to a given formula, the ball required 2 second to 
fall through 10 em. of the solution. 


(3) Torsion Type——In instruments of this type a pendu- 
lum is used to measure viscous resistance. The instruments 
consist essentially of a cup containing the fluid, the viscosity 
of which is to be measured, and a cylinder which is suspended 
in the fluid. In some viscometers, such as the Doolittle, a 
cylinder is rotated in the fluid. The Stormer viscometer 1s 
also of this type. In others, such as the MacMichael, the cup 
containing the fluid is rotated and the viscosity measured by 
noting the angular distance through which a dise is carried 
by the fluid. 


(4) Efflux Type—A great variety of instruments of this 
type are inuse. In its simplest form, an efflux type viscometer 
may consist of a pipette or tube holding a definite quantity of 
liquid; the time required for a given volume to flow out at a 
certain temperature being taken as a measure of the viscosity. 
In most instruments of this class, the liquid flows out under 
its own weight. In several, air pressure is used to produce 
flow. A few of the instruments of this type are the Saybolt 
(U. S. Standard); Redwood (English Standard); Engler 
(German Standard) ; and the Herschel Burette Consistometer. 
These instruments are not as adaptable to the paint and 
varnish trade as to the petroleum industry in which they are 
used widely. 


G. E. Cup for Viscosity—tThe writer’s attention has been 
called to a simple form of instrument used by one varnish 
manufacturer to determime the body of his products. This 
apparatus, which is shown ‘in Fig. 9, consists of a brass cyl- 
inder 17.8 cm. in length and*2.8 cm. in diameter. One-half 
em. from the top is an engraved line up to which it is filled 
with the product. To the bottom of the cylinder is screwed ~ 
a conical shaped nozzle. This has a top diameter similar to — 
that of the cylinder, but it tapers down to an orifice .8 em. in — 


| Consistency 30 
_ re senses 
VISCOSITY CONVERSION TABLE 


Approximate values of viscosity by other instruments as compared to the 
Gardner-Holt Standards 


Gardner Say bolt 
Gardner-Holdt Stds. Mobilometer Engler. Redwood. Universal. 
eS 74 gr. load Degrees Time in Time in 
Letter Poises Giconic: Seconds Seconds 
A 0.50 4.8 8.1 250 285 
B 0.65 6.3 10.0 300 345 
€ 0.85 8.4 Lo27 420 me 4/0 
D 1.00 9.2 16.2 490 550 
E 1,25 12.0 20.0 610 690 
F 1.40 12.5 2055 685 770 
G £05 15.9 26.5 800 910 
H 2.00 16.9 32.4 990) es, 1120 
nf pee Rs) 20.0 30.3 1110 1250 
J 2.50 22.1 40.5 1230 1390 
K Jil fs 24.9 44.1 1350 1570 
L 3.00 25.9 48.1 1450 1650 
M 3.20 29.9 Sit 1560 1770 
N 3.40 33.0 55.4 1690 1900 
O 3.70 34.3 59.5 1800 2040 
IP 4.00 eb 63.2 1950 2190 
QO 4.35 41.3 69.6 2110 2390 
R 4.70 42.3 i 5.9 2280 2590 
S 5.00 47.3 80.0 2430 2740 
a 5.50 50.0 92.0 2800 3160 


length and 3.5 mm. in diameter. The time is taken for the. 
product to flow from the engraved line out of the orifice. This 
apparatus is referred to as the G. E. Cup and is in the class 
of instruments where but one pressure is obtainable, namely, 
the hydrostatic head of the product which is being run. In 
the case of a truly viscous product such as varnish, this cup 
will give a value and a conversion constant may be obtained 
from this value for any specific load that is being used on the 
Gardner-Parks Mobilometer. When a plastic product such 
as an exterior pigmented oil paint is run in the G. E. Cup, 
no conversion factor can be established between the reading 
obtained and the reading obtained with the Gardner-Parks 
Mobilometer for any specific weight that is apphed. Upon 
running a plastic product in the G. E. Cup some of the ma- 
terial will remain in the cup adhering to the walls. This is 
caused by the fact that these products are often so plastic 
that they will not flow, the hydrostatic head having fallen 
below the yield value of the product. Since various paints 
have different degrees of plasticity and hence different yield 
values, the amount of paint that would remain in the cup would 
vary, the density not being proportional to the yield value. 


36 Consistency 


FIGuRE 9 


For this reason, no conversion constant could be obtained 
between the readings on the Gardner-Parks Mobilometer and 
the readings obtained on the G. E. Cup for plastic paint prod- 


Consistency 37 
een 
ucts. It is understood, however, that this type of cup has 
proved satisfactory for factory use in gauging the body of 
elear varnishes and clear lacquers and on products of low 
pigmentation. 

Below are given a few readings obtained with the G. E. Cup 
as compared with those obtained by the Gardner-Parks 
Mobilometer when the latter instrument was run with a brass 
plunger, a perforated brass dise attached and a weight pan, 
these having a combined weight of 74 grams. No additional 
load was applied to the weight pan. Constant temperature 
was maintained throughout and the products were run in one 
type of apparatus and then directly in the other. Lubricating 
oils of non-changing viscosity were used. | 


G. E. Cup Seconds 


esialemeter Seconds Constant 


_ Viscous Propucts 
Mobilometer G. E. Cup Conversion 


Seconds Seconds Constant 
(no load) 
a 2 1.4 29 pais 
es ew ke 5.4 tot 24. 
OU Uy et Se a 6.6 152 23 
G0) een 27.) 520 Zo 


Puastic Propucts 
Mobilometer' G. E. Cup Factor 


ae (no load) 
Flat White Paint ... Dei 99 aya) 
Flat White Paint .... 9.4 40 4.3 
Peterior Gloss ...... BAO 66 Hi, 
Exterior SST eOt Ge 3. ci. 22-0) AAS oo 


It will be noted that no constant factor could be obtained 
with the plastic products, while a factor constant within the 
limits of experimental error was obtained with viscous oils. 


CoNSISTOMETERS 


This class of instrument is designed to cover the entire 
field of consistency from a very low viscosity to a high plas- 
ticity. The Bingham-Green Plastometer is an apparatus in 
which the pressure is variable and almost any substance which 
exhibits a flow may be run upon it. Because of certain appar- 


38 Consistency 


ent limitations and high cost, the industrial application of 
this plastometer in the paint industry has been slow. 


In a most interesting article entitled ‘‘Some Factors which 
Affect the Plasticity of a Paint,’’* E. C. Bingham and A. G. 
Yates describe the result obtained in grinding certain pig- 
ments in various proportions in oil for different periods of 
time in a ball mill. The measurements for yield value and mo- 
bility were made on a plastometer. Important results were ob- 
tained, such as the yield value being independent of the effect 
of the fluidity of the oil; the mobility of certain mixtures 
being but little affected by the size of pigment particles, ete. 
Some of the important conclusions made by Bingham and 
Yates are as follows: 


1—As the grinding of a pigment in oil progresses, the yield 
value at first decreases, but after 30 hours becomes constant. 
The mobility under the same conditions at first increases, 
passes through a maximum, and then decreases more and more 
rapidly. The maximum occurs after about 30 hours in these 
experiments. 


3—Silica and lithopone have very different plasticities at the 
same weight concentration. When. they are compared at 
equivalent volume percentages, however, the mobilities are 
nearly the same and the yield values are not very different. 
This fact is the more striking since the particle size in the two 
pigments is so different. 


4—Comparing blown oil with acid-refined linseed oil at the 
same concentration of pigment, the effect of the fluidity of 
the medium is shown. The mobility falls off in presumably 
the same ratio as the fluidities of the oil, but the yield value 
is independent of the fluidity of the oil. 


5—Polar colloids—as, for example, aluminum stearate—have 
very slight influence on the mobility, but they have an extraor- 
dinary effect in raising the yield value. 

7—Moisture exerts a prodigious effect on the plasticity of 
paint, 0.5 per cent of moisture raising the yield value from 90 
to 3450, and at the same time reducing the mobility to one- 
fourth of its former value. 

8—QOxidation and polymerization affect the fluidity of an oil, 
so we should expect the mobility to be affected. It was thought 


* J. Ind. & Engrg. Chem., Oct. 1923, p. 1033. 


a ee Te eS a eee ee eT ee Ee. ae Vern 


Consistency 39 


that the fall in the mobility on long grinding might be attribut- 
able to one of these causes, but grinding in an atmosphere of 
nitrogen only prevented it, partially. A paint ground in an 
atmosphere of carbon dioxide has a yield value three times as 
high as when ground in the air. 


Gardner-Parks Mobilometer.—This instrument is a consisto- 
meter built to meet the needs of the paint and varnish indus- 
try. It is of low cost, covers a very wide field of consistency, 
may be run with clear or opaque substances and is built of 
a material which will stand factory usage. It is very simple 
to operate and a number of determinations may be run in a 
very short time. The instrument consists of a brass cylinder 
which may be removed and easily cleaned, a plunger which 
fits into the brass cylinder and which is allowed to fall through 
20 em. of the product. 


Method of Use-—Temperature must be taken into considera- 
tion just as with instruments for the measurement of viscosity. 
Provided the room temperature is approximately 20° C. (68° 
F’.), the paint or other products used will not change in tem- 


FIGURE 10 


Mobilometer. 


perature in the short time required to make the tests. It is 
suggested, therefore, that measurements be made at approxi- 


40 Consistency 

mately 20° C. (68° F.). .The cylinder is filled with material - 
to the mark. The plunger to be used is inserted and forced to 
the bottom. .A mark is made upon the rod at the top of the 
bracket when the plunger is at the bottom of the eylinder. 
Another mark is made 20 em. below the first mark. The 
plunger is then raised so that the second line coincides with 
the top of the bracket, care being taken to make sure that the 
dise at the end of the plunger is covered with paint. A weight 
is applied to the pan on top of the plunger and the time im 
seconds for the first line on the rod to coincide with the 
bracket. determined with a stop watch. If desired, the pro- 
cedure may be repeated with a number of different weights 
and the points plotted on a curve. This instrument has been 
used to determine the consistency of a large number of paints, 
enamels, and lacquer products. Some of the results are 
presented below as Tables 5 and 6. The automobile lacquers 
represent a viscuous type of material and when the data are 
plotted the curves are straight lines. The heavily pigmented 
interior flat white wall paints represent a plastie type of 
material and the curves are not entirely straight lines. 


41 


Consistency 


080° scl S&T" GL 160° Ort 680° 0°CT 
690° ovt LLO O'eT Gol 08 L80° a2 vLO Ser 
nae Weg eet oe Beacon Oia aoe a ci SIL" S*g 110° 0°e1 LA de anh 
990° 0O°sT S90: pid | G60" Sor G90 SSE yS0° ost 
ARG hagW Mii canieae’, pi cyanea eet DR aaNet Ne iwi natty PNR ct aa 960" 0°81 nh: viitas 
8&0 S°9C &F0" 07 690° cr 80° i £4 0F0 0°SC 
620" OES ea, eee ee ae Serials Bie Ramah a ate 180° OLE RR ete 
660" SSP 960° 0°6¢ LvO SIc 860° 0°9¢ ¥c0° ie 
610° OES anew 5 i ies bea | ez". res 020° C'6F 
STO 0°29 810° cys c&0 OTe 610° S°cs 910° 0°19 
I10° > Cz" 0°0F CTO" 0°89 eT()" COZ 
eg ety se eee t 9600° Oro! 610° Sees O10" 0°86 600° 0°Sor 
109044 199 spuorag = 19904 199 spuorag —- 10904 199 spuorag wo0ddiaye = Spuovas, ss p90Ad1vay = SpuoIas 
P2d@, HAMM Cd kDa) WW Aidt: bal 46 Bee) A 
Go SN b ON SN CaN PON 


(GANNIH], LON) 


SUMNDOVT ATIGOWOLAY 


G QIAVL 


Gos 
GLY 
Gov 
GLE 
GE 
GLG 
G66 
GLI 
OST 
Gol 
00T 
GL 


SUDAD) Ut 
4aBun) q 
fo 14810 
SN d 
paudd y 
14513 


ee ee eee ae 1 ee ag on Ce eve: ee ne eae or eee FS eae . 


Consistency 


42 


Bites 2 apo PPO’ O°EZ SAP eae, SAM RSS IS celle eh GzG 
eee 8E0° $°9C 002 «6O'S:)=— LOT COO 62 OSE ip orien 5 Sean Be 080" s°7t O0S0° O00 GLP 
pie Dito 120° OLE Benes ntnsak | fesse cea heise Po keaatts ss odes okiberts SS Rtataryl > Rrzeenon 2 || lake) Syoneiata Pe avantoma IR arte SCT Tage 
Seal te wotoaes 610° O°€S zelS's ezI’ 0°8 0z° O'S “eM gt Qco’ O0Z 880° OOf SLE 
002° 0's FS a Pee en EI V7 Re ae Ra en Tg ze 
€rl OZ g00' O'7ST IIT 0°6 680° O7I srl 08 ce «Of 920° S8h +20 OTF 910° O19 GLE 
30° OZ 2Z00' O'8Sh «180° «SIT «G90° SST 001 OOT moIg ee MOIS 672 
PFO’ «O'fZ L000’ O'€67T $90" SST 8h0 OTT 190° OST 02 os MOTS S°7CT MOTS GLI 

dAOW dAOW dAOW 
¥c0 OTP JON §90° O'6T 680 O97 O0S0 0°02 Stiga es JON MOIS JON = OST 
TEM THEM TIEM 
sAOW dAOW sAOW dAOW 
VIO’ OL JON 680° 0°9% 620° SHE FEO SG'6~ Or oor ION JON JON Gol 
TTEM THEM TTEM THEM 
dAOW dAOW dAONW DAO J 
L00° O°EST ION 820 Sse 120° SLb 120° SLP £90 OOF JON JON JON 00T 
TTTM THEA THEM THEM 
DAO dAOW dAOWL DAO 
MO[S AOIS JON LI10° S°8S 10° O'SZ FIO 0°96 TED OE ION JON JON GL 
TTTM TTEAA THEM TTTM 
10904 Spuo 10904 Spuo 10904 Spuo 10904 Spuo 10904 Spuo 10904 Spuo [D904 Spuo DIOL Spuo 10904 Spuo sSmDdr) Uy 
-diay -9aS -duay -9a5 -duway -20G -drway -209 -dray -20g -divay -2a¢ -quay. -9a5 -dway -209 -dway -20G sadunid 
fo 
143184 
‘d “N Ae: iN ee of ae ee gia | tS SE af | Me ed ered a SN d 
pandd y 
6 ON § ON LON 2 ON Guth b ON Peen € ON Fe One 14318 


a ee 


SINIVd TIVM LVI 
9 WIAVL 


Consistency 43 


Comparing Mobilometer and Viscometer Readings.—The 
two types of instruments for measuring consistency, used in 
a be oratory, and to which most attention has been paid 


eee 


0 
] 


] peoys®2 QQ|4O4quty 


5 ete Sia No 
ack 


S 


Pk 
00 
a P 


Ce) 


g 9 
SPu0d2®S O9 GS OS Sv Or GE CE G2 O02 SI Ol GS PeOjONYoJewly 


\ 


ea 
Bes 
NE 
we aN es 
IN 


eles Wee ee alae eal 
eee ene 


lal es Seon el aes ee 


a le ©) NS, aay © en? | Bae Gia 4 boca 3 hae A Maid | las ©. Wag 


AGE cea 
[eS NG es 
ts | ian a 


Smee eS 
a tae ee 


EA Goee 
(aN 
| SSR Ree eee 


in the foregoing pages, are the Gardner-Holdt Viscometer and 


the Gardner-Parks Mobilometer. 


These instruments have 


been particularly described because they were built for the 


44 Consistency 


‘paint and varnish industry in which they are extensively used. 
In order to correlate these two instruments, the oils which 
are used in making the bubble viscometer were run at 25° C. 
on the Mobilometer and a curve plotted with poises along the 
ordinate and time in seconds along the abscissa. The no load 
curve represents the load of the system, which was 74 grams. 
The 100 gram load represents the load of the system plus 100 
grams, or 174 grams. : 

The time, in seconds, divided by the corresponding ntimber 
of poises gives a factor which, when divided into the time 


in seconds reduited toruna svrinle: will give poises viscosity. | 


Thus, if we have for the factor of the no load curve 


Bp. = poises and “Tl == time per te. 
T / : 
Po. hor P Soe 
9.3 | 
and for the 100 gram load, curve eee ts. 
a8 | ‘i 
PS or P == 2025 e8 Bee 


3.98 7 
Seven nitrocellulose solutions were made up with various 


erades of nitro-cotton. Those of the more viscous type were — 


made up on a formula of 8 oz. of cotton to the gallon of solvent. 
Those of the less viscous type were made up with 25 oz. of 


nitro-cotton to the gallon of solvent. After standing several — 
days, a sample of each was put into a standard viscosity tube — 
for running the viscosity with the Gardner-Holdt tubes. The — 
solutions were also run on the mobilometer and the results ~ 
tabulated. The viscosity was then determined by the mobil- — 
ometer method, using the factor obtained with the no load — 
curve on Page 37. The mobilometer results are given below. — 


The greatest difference between the methods is 0.1 poise. 


TABLE 7 
Seconds Required on Poises Calculated Poises Determined — 

Nitro-Cotton Mobilometer at by Mobilometer by Gardner-Holdt — 

Solution No Load 100 gr. Load Factor Viscometer 

Nos. 15.4 6.2 1.65 G Cs 

No, 2 PAN.) 8.8 2.34 1 + T+ 

No. 8 6.2 2.8 66 B B 

No. 4 17.0 G2 1.838 G G+ 

No. 5 170.0 26.8 18.28 — — 

No. 6 13.8 5.2 1.48 F Kr 

NG. ot 3.2 1.8 04 A — A — 


The results derived by factor are taken from the no load readings 


The method that has sometimes been applied to determine 4 
the viscosity of nitrocellulose solutions, namely, the falling” 


\ c q 
{ LK 


9 gr ” 


aaa lel EN Per or ' 
ee ee Se ee ee ee ee er 


_ = 14 A ic 


Consistency 45 


steel ball method, could be replaced with the mobilometer. An 
added advantage is the fact that very exact readings may be 
obtained with pigmented lacquers. The falling steel ball 
method is, of course, not applicable to pigmented lacquers, 
because of the difficulty of reading the end point. 

P. P. G. Consistency Test.—A type of consistency apparatus 
developed by the Pittsburg Plate Glass Co. and subsequently 
used extensively for determining the consistency of pigmented 
products, is described below. 


at Uh re UTE HH 
me 


ul i! Wy yt it 

load H ' 

! Pants EL a wana pate? aie Us as 
| 


KIGURE 11 


Tilting Frame for Consistency Tests. 


Apparatus Required.—A consistency test frame, made of 
wood and having a wood tilting frame to hold a 10” x 12” glass 
plate (see Fig. 11); a standardized German silver tip. For 
a distance of one-half, inch, this metal tip has a 1/16” internal 
diameter hole; one glass tube 131%” in length and having 1%” 
internal diameter. ‘This is cemented to the German silver tip 
with a paste made of litharge and glycerine; one 12” rule 
- graduated to 1/10’; one stop watch; one 10” x 12” glass plate. 


Details of Test.—Testing of paints, enamels and lacquers. 


The finished product is thoroughly mixed by stirring and 
agitation until a uniform mixture results. The consistency 
test is then made as follows: 


The glass plate is placed in a horizontal position in the con- 
sistency test frame. The glass plate and pipette should al- 
ways be clean and free from grease or oil. The pipette is 


46 Consistency 


always filled exactly one-half by sucking at upper end of pi- 
pette. Place finger over upper opening. Slightly releasing the 
finger pressure allows the operator to control the drops. Hold- 
ing the pipette against the notched guide, five (5) drops are 
allowed to fall on the glass plate. As many checks as desirable 
can be run at the same time by moving the pipette to the next 
notch and repeating the operation. Not less than three de- 
terminations should be made. Allow the glass to remain in a 
horizontal position for exactly one minute after the last drop 
hag been placed. The glass is turned to the vertical position 
and the paint allowed to flow downward for exactly five 
minutes by the stop watch. At the end of this time, the glass 
is again turned to the horizontal position and the distance 
each test has run is measured to the nearest 1/10 of an inch 
and the average of the number of determinations taken as the 
result of the test. 

Testing of Dry Pigments——Definite weights of pigment 
and refined linseed oil are used. Usually 30 per cent. by weight 
of pigment in the case of zine oxides and leaded zines and 70 
per cent. by weight of refined linseed oil are used. In the case 
of lithopone it is advisable to use 40 per cent. of pigment and 
60 per cent. of oil. 

The acid number of the oil should be within a close range 
of uniformity on the successive lots of oils used. (3.00 to 3.50 
acid number is a very good average). 

The pigment is placed on a marble or glass slab, a small 
portion of the oil is added and rubbed or mulled to a perfectly 
smooth paste with a glass muller. The balance of the oil is 
added in small portions, mulling after each addition of oil 
until all oil has been thoroughly incorporated with the pig- 
ment. For convenience the oil can be added from a burette. 


Practical Applications of the Spot Test—The spot test for q 


consistency is clearly recognized to be limited in its applica- 


tion, but when carefully used in conjunction with fixed paint ~ 
standards or against a specified ‘‘tail length’’ limit, the spot — 


test has been found very convenient and suitable. 


The precautions to be followed in testing pigments are, — 
certainty of a uniform refined linseed oil of defined acid num- ~ 
ber, a constant and proper ratio between pigment and oil, and ~ 
a standard method of preparing the paint with a laboratory — 


muller. 


a pee " . 
, Oe ae eee ee ae eee ee es 


Consistency 47 


Hickson Penetration Method.—E. F. Hickson of the Bureau 
of Standards has adapted the well known penetration test for 
asphalt to determine the consistency of paste paints which 
range from stiff white lead in oil to the soft semi-paste paints. 
A description of the apparatus and his method, together with 
some very interesting results, as prepared by Mr. Hickson, 
are given below: 


NOTE—This description was originally prepared by FE. F. Hickson for 
Scientific Section Cire. No. 300. 


* FIGurRE 12 


Apparatus for Determining the Consistency of Paste Paints. 


_ Apparatus.—The first cone used in this work was a 45 de- 
gree cone made of aluminum, 3.81 em. (114 inches) in diameter 
at the top, weighing 20 g. The tip was made of steel. The_ 


48 Consistency 


cone was made to meet the dimensions given in the Proceed- 
ings of the A. S. T. M., Vol. 23, Part I, p. 350 (1923), except 
that it was hollowed out to give the desired weight of 20 g. 
The stem of the cone fitted into a plunger 13.65 em. (534 
inches) long by 0.95 em. (% inch) in diameter, made of alu- 
minimum tubing of a size to fit the pentrometer.* The weight of 
the plunger was 20 g., thus giving a total moving weight of 40 
gv. The container was a cylindrical brass cup 9.7 cm, (3% 
inches) in diameter by 7.2 em. (2% inches) deep. (For stiff 
pastes a smaller container can be used. The complete appa- 
ratus is shown in Figure 12. The mirror on the left is used 
in obtaining an image of the cone when the tip just touches 
the surface of the paste. The thermometer, shown on the 
right, placed in a hole for convenience, is used to measure 
the temperature of the paste. The cone on the extreme right 
is the one used later and proposed as a standard for general 
use. 


Procedure.—The thoroughly stirred sample is brought to 


a temperature of 25° C. (+ 2° C.) by means of a water bath. — 


The surrounding air should also be as close to 25° C. as pos- 


sible. It is then transferred to the container and packed in so” q 


as to finally have some of the paste above the sides of the con- 


tainer. The excess of paste is scraped off smoothly and its sur- 7 
face leveled by carefully drawing a straight, rigid, sharp- — 
edged piece of steel across the top of the container. Care must — 


be taken that no ‘‘skins,’’ lumps, or air bubbles are present, as 


these are apt to cause incorrect results. The container is — 


placed upon the stand of the penetrometer and the cone 


brought down at the center of the sample so that the tip just j 
makes contact with the surface of the paste. The indicator — 


arm is carefully brought down so that it just touches the 


plunger and the reading of the dial is then recorded. The : 


indicator arm is pushed back and the plunger is released sud- 


denly and kept released for 5 seconds (stop watch), after — 


which the indicator arm is again brought down so that it 


makes contact with the top of the plunger. The penetration — 
is read directly from the scale, in tenths of a millimeter. Three ; 
tests are made, and the average of the three determinations — 
is reported, provided the difference between the maximum and | 
minimum values is not more than ten points (1 mm). In the — 
case of stiff and medium stiff pastes, several determinations — 


*“Proposed Method of Test for the Penetration of Cup and Railroad — 


Greases,” Proc. A. S. T. M., Part I, p. 518 (1924). 


Consistency 49 


can be made on different parts of the same surface without 
refilling, or the container may be refilled with a fresh portion 
after each determination and the surface leveled as above 
described. Care must be observed, especially in the case of 
soft pastes, to avoid any side effects from the walls of the con- 
tainer. This is taken care of, as in greases, by starting a test 
so that the tip of the cone is never placed closer to the sides 
of the can or to the edge of a previous hole than the penetra- 
tion distance of that particular paste paint. After each test 
the cone is thoroughly cleaned with benzol. 

In Table 8 are given some readings of penetration with 
the preliminary cone on a wide variety of paste paints. The 
precision obtainable by the same, as well as by different 
operators, is shown: 


TABLE 8.—Penetration Results at 25° C. (+ 2° C.) Using First Cone. (40 g. 


load—5 sec. Penetrations). 


Pigment Penetration 


No. Material % (by wt.) mm /10 Description 
1 “White Lead in Oil.............. 92.4 67 Very stiff paste 
gee Winkcerveadain. Oil... :....... 90.0 100 Stiff paste 
a. White Lead in Oil............. 92.2 135 Stiff paste 
# White Lead in Oil.............. 89.1 170 softer than No. 3 
BomviivesLeadein Oil-.,.......:... 92.3 126 Stiff paste 
GeV nite Lead in Oil....:........ 89.9 91 Stiff paste 
Pew nite tea din ‘Oil.,.......:.... 89.1 f118 
\122 Stiff paste 
§ White Lead in Oil............. 90.5 198 Softer than usual 
(a)  () 
(92 (96 
Pee White Lead an Oil:............. 89.8 197 ie Stiff paste 
97 93 
(a)  (b) 
1727 ee a HT 
Poe tute ead in Oil.............. 90.3 5 \131 Softer than No. 9 
125 
(a) (2) 
11 White Lead in Oil............. 89.5 0102106 
(102 4)1101- Stiff paste 
12 White-Lead in Oil............. 91.2 80 Very stiff—no oil 
luster 
See eine Uxide in Oil............... 84.2 124 Normal 
Seneca Oxide in Oil................ 82.0 105 Normal stiff paste 
134 
137 
152 
Boeecine Oxide in Oil................ 81.8 4130 Usual stiff paste 
133 
135 
132 
ieee Oxide in Oil................ 79.8 154 Somewhat soft 
ie ee ARO te OMmMewWNAL SOLU 
Peo Bianc Fixe in Oil................ 79.3 250 Long and stringy 
t> Blanc Fixe in Oil................ 65.0 184 Fairly stiff 


Seance Fixe in Oil................ Toe A EL Re es ice aera A ae a 


50 | Consistency 
Pigment Penetration aie 
No. Material % (by wt.) mm /10 Description 
OG.) “Litanor: te OM ern ae, 82.3 133 Stiff paste 
21) 4 itanox=in Oui, roe en 80.0 {166 ; 
\170 Fairly stiff 
22 B.S. Cir. 89 Semi-paste.... 73.8 f4l11 Thick paint—will 
\407 "run 
23 B.S. Cir. 89 Semi-paste.... 76.9 305 Thicker than No. 


22 


24 B.S. Cir. 165 Olive Drab 
SeMi-paste.,....cccacccsseeereds 73.0 {290 Thicker than No. 
\291 22—will not run 
25 B.S. Cir. 165. Olrve Drab 
STN PARES. Justis asssleetena 78.4 {299 Will not run—me- 
\ 300 dium thick paste 
26 Yellow Ochre in Oil............ 78.9 310 Medium—will not 
Pot Meni 
27 Yellow Ochre in Oil............ ‘eel 320 Medium — thicker 
than No. 30 
(chrome yellow 
in oil) 
28 Yellow Ochre in Oil............ 74.0 314 Medium 
29 Yellew Ochre in Giljae: 69.7 329 Medium 
30 Chrome Yellow in Oil........ 712 [358 
Bee Semi-paste 
31 Chrome Yellow in Oil........ 73.8 358 Semi-paste 
32 Chrome Green in Oil......... 71.6 f405 Thick paint (soft 
\406 paste) ‘‘runny”’ 
33 Chrome Green in Oil.......... 73.9 384 Soft paste, 
4c runny ” 
34 Chrome Green in Oil.......... 79.3 430 Thick paint—thin- 
ner than No. 32 — 
35 Chrome Green in Oil.......... 71.4 450 Thick paint—read- 
ily pours 
36 Chrome Green in Oil.......... 82.6 315 Semi-paste — will 
not run 
of Burnt: Umber nm Ol 2.3 49.9 360 Soft paste 
38 Burnt Umber in Oil............ 60.1 335 Soft paste 
39 Burnt Umber in Oil............ 58.0 388 Quite soft—will run 
40 Burnt Umber in Oil............ 60.6 300 Medium—will not 
run 
41 Burnt Umber in Oil............ 58.2 f222 
\227 Medium stiff 
Ad) Buent Seine iO ais er ae, 278 Medium stiff 
43°-. Burnt Siennarin wo ecee, 62.9 342 Fairly soft—will 
just about run 
44 Burnt Sienna-in Oil............ 61.4 304 Medium — will not 
run 
45. Venetian Red in Oil.......... 68.3 405 Thin paste — will 
run 
46 Prussian Blue in Oil.......... 52.9 eye: 
\277 Fairly stiff 
47 “Rew Uniberin Oil ca 58.1 268 Medium stiff 
48 Metallic Brown in Oil........ 68.8 384 Soft—will run 


Consistency ay | 
a i | el ial le Ne Ee 


Pigment Penetration 


No. Material % (by wt.) mm/10 Description 
Peep oigck ity Oil............: 54.1 {250 
1247 Medium stiff 
90) Drop Black in Oil.............. 48.8 380 Soft paste 
Be vampblack in. Oil.............. 36.5 ore Medium stiff 
248 
pea ealapblack in Oil.......:.:..... DOs Be Medium stiff 
255 
So) wampblack in Oil................ 35.4 344 Somewhat thin 
34 Raw Sienna in Oil.............. 63.6 400 Very soft—will run 
eeteed Leadin: Oil .0..:.......... 93.7 183 Stiff 
paeenea Lead m Oil.................. 93.0 174 Stiff 
pieoiked Leadan Oil................:. 94.0 227 Somewhat soft 
Poemed end an Oil... 93.4 210 Medium stiff 
Seemed Leadein Oil.........:...... 92.7 169 Normal stiff 
60 Ultramarine Blue in Oil... 67.9 [328 Medium soft—will 
325 not run 
Of Urop Black in Japan........ 60.3 201 Medium stiff 
623) Drop Black in Japan........ 56.7 236 Medium stiff 
63 Drop Black in Japan........ 63.2 170 Stiff 
02 Drop Black in Japan........ 56.9 279 Medium stiff 
65 Drop Black in Japan........ 56.5 412 Runny paste—too 
thin 
607 Drop Black in Japan........ 58.2 375 Soft paste 
67 Drop Black in Japan........ 48.0 450 _ Thick paint— 
runny 
68 Lampblack my Jaan... 26.0 450 Very thin—runny 


(a) E. F. Hickson. (6) D. P. Graham. 


The materials in Table 8 represent many brands, and it is 
to be observed that the percentage of pigment does not bear 
any definite relationship to the depth of penetration. This 
is easily understood when the effects on consistency of such 
unknown variables as the acid number of the oil used, size 
of pigment particles, time and manner of storage of the 
finished pastes, possible reaction of pigment and oil, ete., are 
considered. A red lead of high purity (97 per cent of Bp.Gs), 
for example, when freshly mill-ground, in identically the same 
way, to a paste containing 93.5 per cent of red lead and 6.5 
per cent of raw linseed oil, gave a penetration of 295 when 
the oil was practically neutral and 207 when the linseed oil 

had an acid number of 6.0. 


The time and manner of storage have an important bearing 
on consistency. Red lead in oil may become in a few months 
so thick and hard as to be worthless. Whether other pigments 


52 Consistency 
ee LL LL 
in oil change in consistency is open to question. The only 
figures available are the following: 

Penetration 


Material . mm /10 Date 
Burnt: Sienna mm Or, aes: 304 Aug., 1924 
Burnt Sienna in Oil........ 308 Mar., 1925 
surnt Unber, insOil. < eoi.ies 388 Nov., 1924 
2urnt Umber in Ol o.oo 390 Mar., 1925 


These two earth colors in oil apparently did not change in consistency. 

The effect of ‘‘working’’ or mixing an unworked grease is 
to give a higher penetration reading (softer paste). Paste 
paint materials such as putty would do the same thing to a 
certain point. For most paste paints in oil, however, 1 1s 
believed that after a first thorough mixing, the consistency 
remains about the same during the test. A few data have 


been optained as follows: 
Penetration 


Material mm /10 
Zin€ Omdde: in OW. 6 ve-sig.siges erie bie sie wet eee By method... 4..0ea 133 
Excessively mixed for 
ten minutes after ob- 
taining above result... 134 
Fine Oxide in: O14. he 25 Pe eee ai ee By methoG...e256. 125 
Excessive mixing for 
five minutes... eee le 
White Lead in Oil. ..... 0.5.00). Secs owes se sey SOG 105 
Excessive mixing for 
five Mminttes/jaeeeee os. tise 


The effect of temperature on the penetration of paste paints 
was observed on a few samples. It appears to be but very 


slight. For example, the penetration of a sample of titanox — 


in oil was 123 at 20°C and 130 at 40°C. While the results in 
this paper were obtained at approximately 25°C, it is believed 
that, ordinarily, temperature control is of smali moment. The 
effects of load and time on penetration were also observed. 
For most of the samples tested, the five seconds of time gave 
practically all the penetration. In a few instances, notably 
blane fixe in oil, the penetration was not complete in 30 
seconds. 

Recently a new cone for grease has been adopted as a tenta- 


tive standard of the American Society for Testing Materials. 
The diagram of this grease cone with the latest revisions is 


shown in Figure 2 of the A. 8S. T. M. Tentative Standards, — 
1926, p. 418. It is also shown in the Proceedings, American — 
Society for Testing Materials, Vol. 25, Part I, p. 703 (1925), — 
but some minor revisions have been made since this was pub- ~ 
lished. This is a double taper cone, consisting of a 30 degree — 


* Possibly some thinning. 


Consistency why 


steel point and the upper part a 90 degree brass cone. While 
the preliminary work with the first cone described in this 
paper gave satisfactory results, this new cone seemed to offer 
distinct advantages. A cone made to the dimensions of the 
new grease cone (as shown in the A. S. T. M. Tentative Stand- 
ards, 1926, p. 418) but much lighter, was therefore tried out. 
The upper part of the new cone, measuring 6.51 em. (23/5 
inches) in diameter, is made of hollowed aluminum, so that 

§50 


PENETRATION- TENTHS OF MILLIMETERS - NEW DOUBLE TAPER CONE 


0 50. 100 =150 §=©200 ©6250 300 350 400 450 500 550 
PENETRATION-TENTHS OF MILLIMETERS- OLD CONE 


FIGuRE 13.—Comparison of Both Cones. 


with the steel tip the complete cone weighs 35.7 g. and meas- 
ures 4.32 cm. in height. The aluminum plunger weighs 14.3 
g. thus giving a total moving weight in the test of 50 g. By 
adding a 100-g. weight, the new cone should correspond to 
the grease cone having a total moving weight of 150 g. In the 
photograph the new cone is shown at the right. 


The new cone (with a moving weight of 50 g.) was com- 
pared with the 45 degree cone (40 g. moving weight) on a 


54 Consistency 


sample of white lead in oil. This sample gave a reading of 
128 with the 45 degree cone and 173 with the new double taper 
cone. Raw linseed oil was then added to this paste im suc- 
cessive portions, and penetrations obtained with both cones. 
In order to obtain values below that of the original sample, 
dry white lead was thoroughly kneaded into this white lead 
in oil, finally giving a very stiff putty. 


The comparison between the two cones is plotted in Figure 
13. The decided advantage of the new cone in giving higher 
readings on stiff pastes is apparent. On soft pastes, readings 
become less than those obtained with the first cone. It is 
noticed that there is a break in the curve. This break is due 
to the two tapers of the new cone. 


There are shown in Table 9 some experimental and calcu- 


lated values for various paste paints, using this new cone. 
The calculated values were obtained by determining the pene- 
tration with the first 45 degree cone described in the prelimi- 
nary work and then from the graph in Figure 13 reading off the 
values for the new cone. The actual values for the new cone 
were then determined. 


TaBLE 9.—Comparison of New and Old Cones at 25° C. 


Penetration 
New 
Old Cone Double Taper Cone 
Heper- Cal- Haper- 


Material imental culated imental 
White Lead ‘in Oil....:. 310 295 290 
Chrome Green in Oil.... 346 310 305 
Yellow Ocher in Oil..... 380 330 330 
Vermilion: In Ole. wes 160 190 198 
White Lead in Oils 2.5 90 130 131 


With very thin pastes of white lead, it was noticed that the q 


displacement on the upper portion of the double taper cone 
gave rise to slight buoyancy effects. This was not noticeable 
in the thicker pastes. 


The range of usefulness of this new cone was found to be — 
quite similar to that of the preliminary cone first described. — 
The precision obtainable by the one operator with the new ~ 
instrument was about 3 per cent. Since the dimensions, in- © 
eluding tolerances, of this double taper cone have been care- 


fully worked out and standardized for grease by the American 
Society for Testing Materials, it is recommended in its modi- 
fied form for use in testing the consistency of paste paints. 


The penetration method is believed to be of considerable — 
value in rating different lots of the same type of material. It — 
is certainly superior to the usual method of placing a stick 3 


a ne ee See 


eT ee 


~ nals atin 


AS ge, ee Oe ae 


Consistency ao 


or spatula in the can of paste paint and giving the description 
of its consistency. With the new cone, different types of paste 
paints can apparently be roughly grouped in the following 
classes: . 


(ONS 0. I rr less than 100 
ee ee eed ek LOUs tam iio 
Beirne pastes... ol ee ee lee) ines PAN) 
Oh ee ke eb as 200 to 325 
Perr een) Wastes... ..........-4.6.. 320 to 430 


The test does not make a distinction between the length and 
shortness of paste paints (which probably depends upon at 
least two factors, yield value and mobility), nor does it meas- 
ure their tackiness or stringiness. | 

Flowmeter for Mobility of Enamels.—A flowmeter which 
the writer designed a few years ago for determining the flow- 
ing properties of various pigmented mixtures is shown below. 


FIGURE 14 


Two Views of Gardner Flowmeter. 


The apparatus designed is shown in Fig. 14. It consists of a 
heavy piece of plate glass having a series of concentric rings 


56 Consistency 


1% inch apart, etched on one side, a brass cylinder for holding 
the paint, and a frame into which the cylinder is fitted so that 
‘+t ean be raised vertically. The frame is fitted on two sides 
with adjusting screws which permit accurate centering of the 
cylinder. The instrument 1s operated by inserting the brass 
eylinder firmly upon the plate, and filling it level with the 
coating material to be tested. The cylinder is then quickly 
lifted and the coating material allowed to drain out. 

The plate should be carefully leveled before using. When 


the cylinder is raised the material flows out covering a circular 
aren. It is essential that the surface be absolutely clean and 


FIGURE 15 


View of Cylinder and Disc. 


dry; otherwise the area covered by the material will not be 
circular and readings will be inaccurate. In cleaning the 
plate, the writers have proceeded in the following manner: 
After a test, the plate is wiped off with a gasoline-soaked rag, 
then thoroughly washed with soap and water, and later 
cleansed with aleohol. A mixture of equal volumes of benzol 
and alcohol was also found useful in cleaning the plate. It is 
then wiped dry with a soft piece of cloth. When thus cleaned, 


very smooth cireles as much as seven inches in diameter can be 3 


obtained. 


The cylinder may also be used in conjunction with the dise 
shown at © in the figure, for determining the weight of a 


gallon of paint or other material, where only small quantities q | 


are available. It is made to contain exactly one cubic inch, 
hence it is only necessary to multiply the weight of a cylinder 


filled with paint by 231 to get the weight per gallon. Approxi- 4 | 


eee ee eee a ee eS ne ee 


Aare 4 ot ee Pe” ek 2 


Consistency ys 


mate specific gravities and bulking values of the pigments 
used in milled paints can also be estimated very quickly. 


When the cylinder is raised, the paint levels out very quickly 
at first. Paints of a thick, mushy consistency practically 
cease flowing in from 14 to 14 minute. Other paints continue 
to flow over a much longer period of time. Some of those 


Oooo 
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Diameter of flow in inches 


Time in minutes 


1, Raw Linseed Oil 3, Zinc Oxide in Raw Linseed Oil 
2, Spar Varnish 4, Zine Oxide in Spar Varnish 
Figure 16.—Curves from Results on 


examined were still flowing appreciably after 10 minutes. 
These differences in rate and extent of flow might be explained 
by reference to yield value, which is defined as the resistance 
to flow due to the friction of the pigment particles. The hydro- 
Static head of the material causes the paint to flow, while the 
yield value opposes flow. High surface tension also tends to 
decrease flow. The effects of both yleld value and surface | 
tension probably remain constant (during a determination), 


58 Consistency 


while the hydrostatic head gradually decreases. We thus 
have the hydrostatic head opposing the combined forces of 
yield value and surface tension. 


The paint continues to flow until the opposing forces are 
equal, that is, until the hydrostatic head has fallen to such a 
value that it no longer exceeds the combined effects of yield 
value and surface tension. Paints of good flowing properties 
would therefore have low yield values. Low surface tension 
would also promote flowing. 


A little difficulty was experienced at times in controlling 
temperature which, of course, has considerable influence on 
flow. On cold mornings it was necessary to heat the plate and 
then allow it to cool to room temperature before using. With 
the laboratory maintained at 70-75° F., it was possible to check 
results quite closely, usually to 144 inch diameter of flow. The 
results obtained by different operators also checked very well. 


During the course of the work a large number of determina- 
tions were made. Some of the results are given below. 


TABLE 10 


Dry LitHoponges GROUND IN LINSEED O1L*—Diameter of Flow in Inches 


Time in Yo 3 AE a A 3 4 5 < 10 


Minutes 

Noe ieee 30541304 1334 |334-41934-+1924-+1324-41324-41934-415344 1934-4 
eo 254 los -+ 1256-41296 |256-+|254-+|254+|296-+|294-+|256-4256+ 
Se ie 94 (294 (284 \294 [294 [asa |asq+lode+|234+|284+[284+ 
Oe 3. bs Ie 4+ [sb lee ego 
Ce eens 34 4 b+ Br b+ B+ [3eaieeeeeene nares 
No. 8. /svertau [33a [aoa [334+ l3x-+13%4-4 1934-41344 (394 +3344 


* All paints were made up in the proportion of 100 grams pigment to 100 grams — 


raw linseed oil, In this proportion some samples yielded products of much heavier 
body than others. 


ey, CPR ee ee ae ee te 


ee a ey ee 


CHAPTER III 


HARDNESS AND ABRASION RESISTANCE 


Methods for determining the hardness of varnish films have 
been greatly desired. With a suitable method much informa. 
tion regarding the comparative value of various varnishes for 


a foo 


i= Vy Sd. 


—- 


ei; 
“aN 


UMMM EZTV 


HIGURE 17 


Design of apparatus showing weighted sapphire needle on coated 
; surface. 


use in floor coatings and for similar purposes could be ob- 
tained. In this chapter are described various methods that 
have been proposed for determining the hardness of films, to- 
gether with a piece of apparatus recently devised at this 
laboratory for this purpose. 

Laurie-Baily Apparatus.—An apparatus developed by Dr. 
A. P. Laurie and F. G. Baily of Heriot-Watt College, Edin- 
burgh, is described by Holley* as follows: 


An instrument for this purpose has been devised by Dr. A. 
P. Laurie and F. G. Baily of Heriot Watt College, Edinburgh, 
the essential features of which are a central rod sliding easily 
in a vertical direction through holes in two brackets. The 
upper portion of the rod has a screw thread, on which is a run- 
ning nut. By means of a milled head at the top the rod is 
twisted round, and the nut caused to travel up and down on 
the thread. A spring is attached at its upper end to the travel- 
ing nut at the lower end to the lower bracket. To the lower 
end of the rod is attached a hardened blunt steel point, and the 
varnished plate to be tested is placed under this point, and 
the point brought to the surface of the varnish The test 
Surface is drawn slowly under the point, the pressure being 


7—_—_-__ 
“Analysis of Paint and Varnish Products, 274. 


60 Hardness and Abrasion Resistance 


‘nereased until a white scratch is observed, at which point the 
reading is noted on the scale. The machine reads to a maxi- 
mum of 2000 grams. Spirit varnishes break down at a pressure 
of about 100 grams, rosin varnishes 200 to 400 grams, fairly 
eood common varnishes at about 700 grams, and fine carriage 
varnishes at 1200 grams and upwards. The inventors claim 
that the best oil varnishes take twelve months to reach their 
maximum hardness, and that the rate of drying and the ulti- 
mate hardness can be measured with accuracy by their instru- 
ment. 


Fraure 18.—Clemens Apparatus showing weighted knife on coated panel. 


A set of this apparatus obtained by one of the writers as far 
back as 1910 was available in this laboratory for experimental 
purposes and was used in a number of determinations, de- 
scribed later in this chapter, upon a series of varnishes. 


Clemens Apparatus.—Another apparatus for determining 
hardness of varnish films, known as the Clemen’s* Hardness 
Tester (see Fig. 18), and made in Germany, consists of a bal- 
ance beam with one arm slightly longer than the other. The 
longer arm carries on the under side a portion of a knife 
blade, and on the upper side a post upon which are placed — 
weights. The sample is placed on a holder and drawn along — 
under the knife blade. The weight and the nature of the ~ 
scratch are then considered in determining the hardness of the — 
sample. From a few experiments made with this apparatus, 


*Made by Hugo Kenl, Dresden. 


Hardness and Abrasion Resistance 61 
ss Ga SE aed rere ae ines 
it is not believed that it offers any advantage over the type 
referred to on page 59. 

Wilkinson Pencil Method.—Another method for determining 
the hardness of varnish films was outlined by W. H. Wilkin- 
son in his paper, entitled ‘‘Methods for the Determination of 
Comparative Hardness of Varnish Films”’ (see page 302 of the 
Proceedings of the Scientific Section for 1923).* For this 
method, seventeen grades of Dixon’s Eldorado pencils are 
used. These pencils are drawn across the varnish film until 
an end point is reached. This end point is indicated when one 
pencil is found which will not cut the varnish, leaving a black 
pencil mark on the surface, whereas the next harder pencil 
will cut through the varnish without leaving a black mark. 
The number on the harder pencil is then used to express or 
designate the hardness of the varnish. The pencils used by 
the writers are numbered as follows (only twelve were used 
in the tests reported here) : 7H, Giivoleeh. 3H 2H ae a Bb 
B, 2B and 3B. 

This method is, of course, open to such objections as the 
impossibility of applying the same pressure by different oper- 
ators; possibility of different operators holding the pencils 
at different angles; lack of uniformity in the sharpness of the 
pencil points; and in the hardness of pencils of a particular 
number that are purchased from lots in various sections of 
the country; and the freedom from hard spots in the graphite. 

Laboratory Scratch Hardness Tester.—The writer has at- 
tempted to eliminate some of the difficulties offered above by 
devising an apparatus constructed upon a balance beam simi- 
lar to a Westphal balance for determining specific gravity. 
At one end of this beam a clamp is fixed, which will hold a 
pencil at an angle of 45° to the beam and pointing away from 
the fulerum. At the other end of the beam a wei ght is placed 
so that the beam will be exactly in balance. A hook, upon 
which the weight is hung, is placed midway between the ful- 
erum and the pencil point, in such a position that the weight 
bearing on the pencil point is approximately half the applied 
weight. In a later model, an arrangement was made for the 
weights to be applied at the top of the beam rather than to 
be hung under the beam. In maklIng the test, the varnished 


* Scientific Section Circulars are published monthly at this laboratory and 
forwarded to all members of the American Paint and Varnish Manufacturers 
Association. 


62 Hardness and Abrasion Resistance 


plate is placed under the pencil points, the desired weight 
applied, and the plate then drawn slowly under the points im 
the direction away from the fulcrum. 


In the investigation work, the pencil points were sharpened 
in a number of different ways, namely, on a pencil sharpening 
machine, by rubbing the pencils on sand paper to a flat, chisel- 
like point, and by rubbing the pencils on sand paper to a 
rounded point. As a result of this work, it is the writers’ 
opinion that the most important source of error in the use of 
pencils is due to-the point used, as the pencils cannot be 
sharpened to exactly the same point. Small pieces of graphite 
may chip off of a very hard pencil, while a soft pencil will 
wear away very rapidly. Entirely different results were ob- 
tained with the different methods of sharpening, on something 
like three hundred different determinations. The writer is 
frank to admit, however, that no definite statement can be 
made that there is a lack of uniformity in the hardness of the 


pencils used or in the graphite used in their manufacture. — 


However, such difficulties might arise at any time and might 
tend to vitiate the results obtained by different operators. 


A still further set of apparatus was constructed to hold eight 
of the pencils of varying degrees of hardness at one time. 
They were set in a clamp at an angle of 45° to the beam, and 
pointing away from the fulcrum. The varnished plate was 
drawn under them and then examined. It was found impossi- 
ble to get the pencils in perfect alignment, and the rapid wear- 


ing down of the soft pencils added to the difficulties encount- — 


ered. This apparatus was therefore discontinued in the tests. 


Sapphire Point Talking Machine Needle.—As a result of a — 
later thought, it was decided to include in this investigation — 
a sapphire point needle such as is used quite extensively upon — 
talking machines in place of steel needles. The needle was ~ 
fastened to a glass rod which was inserted in the apparatus in ~ 
place of the pencil. It was found, however, that this needle, g 
even without any weight, was able to scratch any type of 4s 
varnish film. Nevertheless it was found by microscopic ex- ~ 
amination of the scratched test plates that very marked differ- g 
ences were shown in the character of the abrasions made by ~ 
the sapphire point. For instance, it was found that boiled oil — 
coatings and long oil spar varnishes almost invariably showed ~ 
a type of rupture that was different from that indicated by ~ 


le i a gS arn 


et a , » ’ 
ee ee a” a € w 


at 


Ne Ve ae 


et 
ee 


| Hardness and Abrasion Resistance 63 
——$—— 
hard drying varnishes. That is brought out in the photo- 
micrographs attached herewith. As a result of this work, it 
is indicated that in place of pencils, the apparatus shown in 
the illustration Fig. 17 could be fitted with a sapphire point 
needle, and a qualitative interpretation of the results made 
after microscopic examination of the films. Nothing in the 
way of quantitive data would result. 


I—Sapphire point test at 500 grams on flat white paint dried 15 days. 
Ii—Sapphire point on hard varnish film. III—H2 pencil. IV—H5 
pencil at 200 grams on varnish dried 15 days. 

FIGURE 19 


64 Hardness and Abrasion Resistance 


V—aAuto finishing varnish. VI—Thirty gallon tung oil spar. ViI—Twenty 
gallon tung oil spar. VIII—Floor varnish. IX—Shellac. X Congo 
linseed spar. All tests made with sapphire needle at 200 
grams on films dried 15 days. 

FIGURE 20 


XI—2B pencil on gloss white. XII—3H pencil on flat white. XIII—B pencil 
on gloss white. XIV—7H pencil on flat white. XV Sapphire 
point test on flat white. XVI—Sapphire point on gloss 

white. All tests made with our apparatus on films 
. dried 30 days. 


FIGURE 21 


66 Hardness and Abrasion Resistance 


Tungstone Point.—A tungstone point that was used for 
playing several records was tried in the apparatus. This point 
‘s much less hard than a sapphire point or steel point. It was 
found by miscroscopic examination that the wear on one side 
of this point makes a great deal of difference in the breaking 
of the varnish film. When the flat side is used, no abrasion of 
the film was noticed until large weights were applied. When 
the pointed side was used, the film was broken with only a 
very small weight. It 1s not believed that the Tungstone point 
offers any advantages in this work. 


Preparation of Films.—For the experimental work, var- 
nishes were flowed upon several small glass panels in the 
usual manner, standing them vertically to dry. Some of the 
glass plates used were given a rough surface by grinding 
with coarse emery powder and then rubbing down with fine 
emery powder; the varnishes later being applied. No differ- 
ence, however, was shown in the value of the two different 
types of plates for, this purpose. h 


One of the glass plates used in the experiments, after being 
coated, was allowed to dry for forty-eight hours and then was 
ruled off into a number of small (14-inch) squares. Such a 
great variation in apparent hardness was obtained with the 
Laurie and Baily apparatus that it was thought impossible 
to obtain an accurate reading on any one of the given squares — 
of the plate. For instance, where the varnish flowed from the — 
top of the plate, a harder surface was shown than near the — 
bottom of the plate where the varnish had accumulated to a 
thick film during drying. This result indicated the necessity — 
of having a uniform thickness of film over the entire area of — 
the glass plate. Accordingly, a revolving dise was con- 
structed, using the type of apparatus described by Walker 
and Thompson in their paper on the ‘‘Physical Testing of 


Varnishes’’ (Proceedings of the Amer. Soe. for Test. Mater., 4 


1922. Part II, page 464). It was driven by a small motor 


available in the laboratory, at a speed of 300 R. P. M. The ~ 


glass plate was inserted in the top of the apparatus, a definite 
amount of varnish poured on the middle of the panel, and the — 
motor started. After spinning for a period of three minutes, . 
the panel was taken out and allowed to dry. The films ob- — 
tained with this apparatus were much more uniform and 
entirely satisfactory for the purpose of the investigation. 


Hardness and Abrasion Resistance 67 


A number of varnishes were then selected, with a view of 
obtaining variation in the hardness of the dried films. - These 
were spun in the apparatus referred to, dried, and allowed to 
harden for different periods of time before testing. It was 
thought that it would be of interest to include in the investi. 
gation some prepared paint and enamels. Accordingly, several 
gloss paints and enamels were brushed out on glass plates. 
Others were whirled in the same manner as the varnishes. 
The charted results of tests are given in the diagram below. 


Discussion of Tests—It will be noticed from the results 
obtained with the mechanically held pencils that each film 
shows a progressive hardening from 24 hours to 48 hours, and 
again at the end of nine days, the different periods at which 
each film was examined. This is true of almost every film 
tested. The progressive increase in hardness referred to was 
also noticed when the Laurie and Baily apparatus was used. 
The results obtained when a number of the varnishes are 
compared show a very little difference, all of them falling 
within very narrow limits after drying the same length of 
time. It was also found to be practically impossible to differ- 
-entiate between varnishes which, because of their varying 
composition and methods of manufacture, are considered to 
be of varying degrees of hardness, when the Laurie apparatus 
or pencil test was used. 


Hardness and Abrasion Resistance 


68 


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Hardness and Abrasion Resistance 69 
a 
Dupont Scratch Testing Machine—The type of instrument 
used at the du Pont lacquer plant at Parlin, N. J., for deter- 
mining the hardness of a lacquer and its resistance to scratch- 
ing, is Shown in Fig. 22. 


FIGURE 22 


Dupont Scratch Testing Device. 


This consists of a wooden base on which are mounted (1) 
a fulerum holding a graduated lever equipped with weights 
and: a needle point; (2) a transformer; (3) a six-volt lamp, and: 
(4) a metal plate. These parts are all connected in series 
with the transformer, the latter being used to step down the 
ordinary light voltage to the voltage of the small lamp used. 


Method of Testing—The metal panel to be tested, usually 
polished brass, is placed coated side up on the metal plate 
under the needle point. The weight is adjusted and the panel 
drawn along the plate by the operator in the direction of the 
long axis of the instrument. This operation is repeated, using 
each time an increased weight, until the lacquer is Steal 
by the needle. When the needle penetrates the lacquer, elec- 
trical contact will be made throughout the system which will 
light the lamp. The position of the weight is then read which 
Shows the pressure acting on the needle point when penetra- 
tion occurred. Comparisons may be made on products of 
different compositions by using a film of the same thickness 
in each case. 


D. V. Gregory has recently examined twenty-six different 
methods for determining hardness, including those embody- 
ing the principles of enone crushing, bendine or impact, 


70 Hardness and Abrasion Resistance 

which he concludes are impractical. He has studied pene- 
tration tests such as those which are represented by the de- 
vices of Keeps, Unwin and John, but has not found them 
suitable for such work. He has also studied the various 
seratch methods, many of which have been outlined above, as 
well as others which are represented by the Turner Schero- 
meter and the micro-hardness test. His conclusions are to 
the effect that the method devised by Dr. A. H. Pfund, and 
described on page 82, is superior to any of the others that have 
come to his attention. 


Swinging Beam Hardness Test.—A method recently devised 
by P. H. Walker and L. L. Steele of the Us $8. Bureau of 
Standards, with an apparatus called The Swinging Beam, has 
been used in this laboratory for three years with generally. 
satisfactory results. A deseription of the apparatus, the 
method of test, and some experimental results as originally 
prepared by P. H. Walker for Scientifie Section Cireular No. 
229 are given below. 


FIGURE 25.—The Swinging beam for testing hardness of films. 


Hardness and Abrasion Resistance 71 


The initial idea for a swinging beam to measure the hard- 
ness of varnish films came from the ‘‘Herbert Pendulum 
Hardness Tester’’ invented recently by Edward G. Herbert 
in Kngland.* | 
“The Herbert pendulum consists of a rocking device weigh- 

ing 2 or 4 kilograms with a one millimeter supporting ball of 
ruby or steel. Normally the center of gravity is adjusted until 
it is a fraction of a millimeter below the center of the ball. 
With the ball resting on the metallic surface to be tested the 
device is set into oscillation through a very small range and 
the time for ten swings is taken. This time varies with the 
nature of the metallic surface to be tested and is called the 
‘pendulum time hardness number.’ The device may also be 
tilted from the horizontal through a standard angle and then 
‘released. The angle reached at the end of the unmediately 
ensuing half-swing is read by means of a spirit level and scale 
on the device and is recorded as the ‘scale hardness number.’ ”’ 


Tt will not be expected that the Herbert device designed 
for testing metal surfaces would be applicable to varnish 
films. After some experimentation the so-called swinging 
beam (see Fig. 23) was devised. It is simply an instrument 
for rocking two equally loaded ball bearings on a varnish 
surface, the theory being that the harder the surface, the less 
damping effect there will be on the movement of the balls. 


The swinging beam as here described differs from the Her- 
bert pendulum in that the period of swing is the same (with- 
in experimental error) on all surfaces whether relatively hard 
or soft. Hence it gives no ‘‘pendulum time hardness number.”’ 
The ‘‘swinging beam factor’’ obtained and described later is 
probably related to the ‘‘seale hardness number’’ of Herbert; 
but differs from it in that it is dependent upon repeated 
(rather than a single) deformations. 


It was found that if the swinging beam was set in motion 
on a varnish film known to be soft, it would come to rest much 
more quickly than on a varnish film known to be relatively 
hard. Experimentally it was not found advisable to wait for 
the beam to come to rest. The beam was set in motion through 
an arbitrarily chosen amplitude and the time taken when that 
amplitude had decreased a definite percentage (for example, 
50 per cent). The detailed description of the operation of the 


*Discussed in The Engineer for June 29, 1925. 


JZ Hardness and Abrasion Resistance 


swinging beam is given later. In the description of the con- 
struction of the swinging beam to follow, it should be noted 
that an attempt has been made to simplify the design as much 
as possible so that working duplicates can be made from easily 
procured materials in any ordinarily equipped machine shop. 


Construction of the Arms.— Figure 24 gives details of the 
construction of the arms of the swinging beam. Steel drill 
rod was selected because of its rigidity and its uniformity in 
dimension for a given gage size. The bends can best be made 
in a vise. The measurement 10.5 em. shown in the drawing 


FIGURE 24 
2 DETAILS FOR CONSTRUCTION OF ARMS. 
6-32 THREAO 


, 
arg 
x % 
‘ 


<i 


MADE FROM NO28S STEEL DRILL ROO 

(STV88S STEEL WIRE GAGE) 
O/AMETER = 0.13924.0005 IMH (SF5X .O15 1m) 
TEMPER 70 BE ORAWN AT BENDS 


3Z THREAO_| 
Se Dae [TT LLL 


represents the distance from the longer arm to the center of 
the 45 degree bend. It will be found advisable to draw the 
temper of the steel at the bending points in order to avoid 
possible fracture. After the proper thread has been cut, the 
long end of each arm should be filed to a V shaped point (See 
Fig. 26) which serves as a pointer. Each completed arm 
should weigh 33 grams + 0.25 g. 


Details for making the brass plate are given in Fig. 25. 
Place two polished half-inch steel ball bearings on a level 
surface and clamp. the brass plate over them so that they fit 
snugly in the proper holes. The top of neither ball should 
extend above the surface of the plates if the holes have been 
drilled to the proper size. Completely fill the space over the 
balls with solder, using a suitable flux, and then file the excess 
of solder flush with the brass plate. The completed ball-bear- 
ing plate should weigh 25 gram + 0.3 g. 


Hardness and Abrasion Resistance iiss 


FIGURE 25 


OETHILS OF BALL. BEARING PLATE. 


70 BE MADE OF SHEET BRASS 
LS MM THICK 


Assembly of Parts—The important dimensions of the as- 
sembled swinging beam are shown in Fig. 25. Attach the 
arms to the ball-bearing plate with four brass nuts which 
should have a total weight of 4 grams + .04 g (approximately 
1 gram each. Clamp the arms in a vise so that their plane 1s 
at right angles to the long edge of the plate. Tighten the nuts 
and adjust the distance between the pointer tips to 58 em., with 
a wire fastened as shown in the sketch and weighing 0.8 gram 
+ 0.05 ¢. (Steel wire American wire gage No. 26 is suitable.) 
Place the assembled beam in a vertical position with the 
pointer tips on a level surface and measure the vertical dis- 
tance to the highest point of each arm as shown in Fig. 26. 
This distance should be 24.5 em. (+ 0.8 em.) and should be 
the same for each arm. If this distance falls outside the above 
limits or if the distance is not the same for both arms, make 
the proper correction by changing the position of the nuts_ 
which fasten the arms to the plate. Place the seven brass 
counterpoise nuts on the pointer end of each arm. Hach set 
of nuts should weigh 7 gram + 0.07 g and they should be 


74 Hardness and Abrasion Resistance 


adjusted to the above weight by suitable means, such as filing 
or adding solder, if their weight is not correct. It will be noted 
that the arms of the assembled beam will be slightly bowed in 
shape owing to the tension of the connecting wire. The com- 
pleted beam should have a total weight of 110 grams + 1 
gram. | 

FIGURE 26 


OETAILS FOR ASSEMBLY OF BEAM. 


ppt hg 
§ i) vy 
re * 
+ ™“ 
N 


SY _-7 BRASS NUYS 6-32 THREAD % gue 
WEIGHT OF EACH NUT = / 644. <) ») 
- 


a 
* 


Construction of the Scale——The distance from the center of 
a ball to either pointer tip in the completed swinging beam 
should be very close to 32.5 em. The pointer of the beam will 
therefore travel along a portion of the are of a circle with a 
radius of 32.5 cm. A general idea of the seale can be obtained 
from Fig. 26. Draw on suitable paper a 90° portion of the 
are of the afore-mentioned circle and lay off two radii at right 
angles to each other. Bisect the 90° are thus formed and con- 
tinue the bisection of the resulting angles until the are has 
been divided into 32 equal parts. Consider the horizontal 
radius as the top boundary line of the scale and mark the 
ninth division below this line as the zero point. Mark the 
division lines on either side of the zero point which correspond 
to an amplitude of swing of 45 and 22.5 degrees, respectively, 
as Number 4 and Number 2 scale divisions, respectively. 
Mount the scale on a suitable vertical support so that the top 
boundary line of the scale will be parallel to the laboratory 


bench. The portion of the are of the circle not included in’ 


the working range of approximately 50° of are may be cut 
away for convenience. 


Method of Using the Swinging Beam.—It was found abso- 
lutely necessary to protect the beam from air currents during 


4 oy TTT ring Pel eta 


a ae eee 


Hardness and Abrasion Resistance 75 


the period of swinging. The analogy between the swinging 
beam and a delicate analytical balance, which is always en- 
closed in a glass case, is readily seen. It is obvious that any 
eabinet with a movable glass door in which the swinging beam 
ean be mounted will serve the purpose. Two parallel, hor1- 
zontal lines should be drawn on the glass door at the same 
respective heights from the laboratory desk top as the 45 and 
99.5° divisions on the scale. These lines are an excellent guide 
to the eye in the proper alignment of the pointer tip with the 
scale divisions. 

It was found that different beams, constructed as described 
above, gave slightly different readings on an arbitrarily 
chosen surface. It was therefore necessary to adopt some 
standard surface of reference in order to make a correction 
for such deviations in different beams. Plate glass was selected 
for such a reference standard on account of its ready avail- 
ability and its relatively smooth and plane surface. The 
method of determining the plate glass blank for the swinging 
beam is given below. The measurements on varnish films 
with the swinging beam are made in essentially the same 
manner. 

Figure 23 should be consulted for the general arrangement 
of apparatus. The glass cabinet to protect the swinging beam 
from air drafts is not shown in this photograph. Thoroughly 
clean the plate glass and the ball-bearing surfaces of the 
swinging beam with ether. Polish these surfaces with a suit- 
able material such as strips of clean filter paper. Hemove any 
visible lint or dust with a fine camel’s hair brush. In case the 
ball-bearing surfaces become tarnished or do not have a high 
polish, rub them lightly with a paste of polishing emery and 
oil on a soft cloth. The emery must be at least as fine as the | 
American Optical Company’s No. 303 grade. Thoroughly 
clean the ball surfaces as described above after such treat- 
ment. 


Place the glass plate on three rigid pegs spaced to form an 
equilateral triangle and fastened in a support of adjustable 
height that is also equipped with leveling screws. (See Fig. 
93). The three pegs should be located near the outer edge of 
the plate in order to produce the maximum rigidity. 


Level the plate with the leveling screws. _A ball bearing is 
a convenient leveling guide since it will tend to roll on a 


76 Hardness and Abrasion Resistance 


sloping surface. Bring the top surface of the plate to the level 
of the horizontal top boundary line on the scale so that the 
pointer of the beam will travel along the are on the scale. 


Place the swinging beam on the glass plate and adjust the 
position of the pointer to the zero mark on the scale by raising 
or lowering the brass nuts at the ends of the arms. In case the 
pointer can not be brought to the zero mark in this manner 
it is an indication that the beam was not constructed accord- 
ing to the specifications given above. Place the scale so that 
the pointer of the beam will travel in a plane parallel and 
near to the scale. 


The swinging beam should have a period of approximately 
_ 36 swings per minute. Start the beam in motion through an 
amplitude of approximately 45 degrees of are. With a stop 
watch measure the time that it takes the pointer to pass the 
zero mark 36 times. This time should be within the limits of 
58 to 65 seconds. If the rate falls outside these limits, raise or 
lower the brass weights on each arm to increase or decrease, 
respectively, this period. If this adjustment does not effect 
the desired result, increase or decrease the distance between 
the pointer tips by a readjustment of the connecting wire to 
increase or decrease, respectively, the period for 36 swings. 
Do not adjust the distance between the pointer tips outside 
the limits of 57.5 to 58.5 em. When the beam has been ad- 
justed for the proper period of swing, it is ready for the blank 
run on plate glass. 


Readjust the pointer, if necessary, so that it coincides with 


the scale zero mark when at rest and then carefully push the 


pointer to a position approximately one-half a division beyond 
the fourth scale mark (corresponding to an amplitude of 
swing of slightly over 45° of arc). Close the door of the pro- 
tecting cabinet and align the eye with the fourth seale division 
line by aid of the guide line marked on the glass door of the 
cabinet. Start a stop watch when the pointer tip at the top of 
the swing coincides with scale line number four. Stop the 
watch when the amplitude of swing has decreased 50 per cent. 
that is, when the pointer tip coincides with seale line number 
two at the top of the swing. This period of time is the ‘‘glass 
swing’’ of the beam and its use is described below. While the 
time is recorded in the smallest intervals indicated by the 
stop watch, it is evident that it is given in multiples of the 


’ rs P ~ a whe wn Wi 


Hardness and Abrasion Resistance 77 
——E—_—_—_—_—___—_—_—_—— 
time of one swing. Hence, although more tedious, the number 
of swings may be counted and the stop watch dispensed with. 


Table 12 gives characteristic data for four swinging beams 
and indicates the need for the blank swing on glass in order to 
correct for the slightly different values obtained with different 
beams on the same varnish film. The ‘‘swinging beam factor’? 
given in Table 12 is calculated by dividing the time swing of 
the beam on varnish by the corresponding measurement on 
glass. Results are shown in Table 13 for two amplitudes of 
swing, 45° to 22.5° and 45° to 11.25°, respectively. In all 
succeeding work, the former amplitude of swing has been 
selected as the most suitable one for general use. A. three- 
week-old spar varnish film prepared as described in paragraph 
IV (b) was used in the comparison of the four swinging beams. 


TABLE 12 
Typical Data Obtained with Four Different Swinging Beams. 
(All values for swing of the beam represent the average of five determinations 
7 expressed in seconds. ) 


Beam Beam Beam Beam 
No. 1 No. 2 No. 3 No. 4 
45 to 22.5° Swing on Glass 345.5 331.1 330.7 338.1 
45 to 22.5° Swing on Varnish 200.9 190.7 192.4 193.2 
45 to 22.5° Swinging Beam 
Factor for Varnish....... 0.582 0.576 0.582 0.572 
45 to 11.25° Swing on Glass 792.2 749.1 761.4 773.5 
45 to 11.25° Swing on Var- 
SIC a) ik laa ee a eee 359.5 3338:5 334.9 338.9 
45 to 11.25° Swinging Beam 
Factor for Varnish ...... A454 445 440 438 
Time Period for 36 Swings 
PRACT E aia elas ie he eww a Phe 60.7 nS. 58.0 60.2 
Total Weight of Beam.... 110.7¢ 109.0 g 110.6 g 110.0 ¢g 


Table 13 shows additional characteristic data for the swing- 
ing beam. It is to be noted that the time period for 36 swings 


THE SWINGING BEAM METHOD OF TESTING VARNISH FILMS 


TABLE 13 
Miscellaneous Data on the Swinging Beam 


(All determinations made with the same instrument and the time expresed 
in seconds. ) 


Time necessary for 45° to 22.5° Swing 45° to 11.25° Swing 

6 Swings on pol- on pol- on pol- on pol- 

on plate on Spar on plate ished ished on plate ished ished 
glass varnish glass steel quartz glass steel quartz 
60.2 60.0 343.6 344.8 346.5 788.0 794.8 797.4 
60.2 60.2 342.5 343.5 342.9 786.4 791.3 790.2 
60.4 59.8 341.0 349.0 343.0 780.6 810.2 780.8 
59.9 60.1 344.8 347.4 346.4 784.2 806.0 796.8 
59.8 60.3 344.8 343.0 344.2 778.6 97.7, 783.8 


Av. 60.1 Av. 60.1 Av. 343.3 Av. 345.5 Av. 844.6 Av. 783.6 Av. 800.0 Av. 789.8 
coo seen ces mee ee ERR BT RC SRI aA a OC a SLA RN Meal gL ER Cas Ber ee 


78 Hardness and Abrasion Resistance 


of the beam is independent (within the limits of experimental 
error) of the surface used. It is also to be noted that the 
swinging beam behaves essentially the same on plate glass, 
polished steel and polished quartz, respectively. The order of 
the deviation to be expected between separate determinations 
with the swinging beam on the surfaces mentioned above is 
also notworthy. 


Preparation of Varnish Films.—A standard method for pre- 
paring varnish films was obviously necessary in order to 
obtain results of a reproducible nature. The whirling disk 
method of Walker and Thompson* was adopted for the prep-. 
aration of all varnish films in this work. This method makes 
it possible to reproduce varnish films of uniform thickness 
for any given sample though it would be expected that differ- 
ent varnishes would give films of different thickness. Glass 
plates approximately 25 em. in diameter were used, but the © 
size of the plates is not an essential factor. It is probable that 
square plane surfaced plates would work satisfactorily. In 
the work described below, the middle of the plate was covered 
with an excess of the respective varnish and whirled at 300 
R. P. M. for three minutes. This method probably yields a 
considerably thinner film than an average brushed coat of the 
same varnish. This fact is immaterial because the swinging 
beam yields comparative figures and not absolute values. 


Measurements on Varnish Films.—In all eases five meas- 
urements with the swinging beam were made on a given var- 
nish film at equally spaced locations, at a fixed distance of 5 
cm. from the edge of the glass plate to the center of the ball- 
bearing plate. <A circular cardboard guide with rectangular 
holes approx. 15x40 mm. at the proper points used as a guide 
under the test plate was found to be convenient. 


As might be expected, varnish films prepared by the whirl- 
ing disk method were not absolutely uniform and consequently 
showed some variation in the swinging beam measurement at 
different points. It was decided that the average of five read- 
ings would furnish a value sufficiently accurate for ordinary 
purposes, and that the greater degree of accuracy which might 
follow from a larger number of measurements would not justify 
the added labor and time. 


*Proceedings of the Am. Soc. for Testing Materials, Vol. 22, Part II, p. 465 
(1922). . | 


Hardness and Abrasion Resistance 79 


The data given in Table 14 are intended to show the order 
of the deviation in readings which may be expected on 
whirled varnish films. Incidentally these data show the pro- 
gressive hardening for three distinct types of varnish after 
successive intervals of drying time. 


TABLE 14 


(All readings represent the time in seconds for a reduction in the amplitude 
of the swinging beam from 45 degrees to 22.5 degrees of arc.) 


. After one After two After five 
Varnish . day’s drying days’ drying days’ drying 

Spar 133.5 159.6 226.2 
132.1 157.0 199.0 

132.4 163.6 201.2 

130.2 156.0 205.2 

128.6 163.4 205.0 

Av. 131.4 Av. 159.9 Av. 208:3 

Floor 129.8 169.2 205.0 
141.6 177.6 225.0 

141.6 182.4 221.2 

150.0 172.8 214.6 

139.0 170.0 195.0 

Av. 140.4 Av. 174.4 Av. 213.4 

Rubbing 227.8 259.6 264.8 
223.0 246.2 234.6 

228.4 243.6 283.6 

226.0 254.2 277.8 

221.8 249.2 283.0 

Av. 225.4 Av. 250.6 Av. 268.8 


The general method for making swinging beam measure- 
ments has been described above. There are certain additional 
details to be noted in the use of the beam on varnish films. 
With relatively soft films (such as a Spar varnish) it is neces- 
sary to clean the ball-bearing surfaces with ether, as already 
described, after each separate measurement on different por- 
tions of the film. Care should be taken to remove any dust 
either on the ball surfaces or on the varnish film with a fine 
camel’s hair brush. In the case of very soft films the damping 
of the beam’s swing will be very rapid so that there may be 
difficulty in measuring with precision the time interval be- 
tween the amplitude of 45° and 22.5° of swing. The operator 
in such cases must approximate this reading as closely as 
possible. It may be found advisable to dispense with the stop 
watch and count the swings, estimating fractions of a swing 
as frequently done with an analytical balance. 


In Fig. 27 the swinging beam factors are plotted for seven 
different varnishes after periods of drying. The shellac var- 


80 Hardness and Abrasion Resistance 


nish was made from ‘‘D. C.’’ orange flake shellac and 95 per 
cent denatured alcohol and contained 35 per cent of non-vola- 
tile matter. Varnishes numbered from 1 to 6, inclusively, 
were commercial products from a large varnish manufacturer 
and described as follows: 

#1 ‘‘Congo-China Wood oil polishing and rubbing varnish. ”’ 

t2 “‘Same as tl, but more elastic. 

#3 ‘‘Hardened rosin-China wood oil general utility var- 
nish.’’ 

#4 ‘‘Fossil gum-China wood oil floor varnish.’’ 

t5 ‘‘ Auto finishing varnish.’’ 

t6 ‘‘Waterproof ester gum-China wood oil Spar varnish.”’ 
Lo FIGURE 27 


COMPARATIVE OATA 
ON DIFFERENT VARNISH FILMS. 


) SHELLAC 
<a VARNISH #1 
° P 


Ss 
L-) 


S 
ap 


BLAM LMT OR 


VARN/SH #2 
06 VARNISH #5 
#4 
S VARNISH 
BOF 
N VARNISH #6 
Sos 
° 
N 
05 
NS 0 
* 
Ley ya ee. VARNISH #.&- 
.s 


a 


/ z 5 Fo F 6 7. & 9 
TIME OF DRYING /N OAVS 


It is believed that a practical varnish man from the above 
description would say that after drying for a week the shellac 
would be the ‘hardest, ’? varnish No. 1 next in hardness, var- 
nish No. 2 next, varnish No. 5 softest, and the other three 


varnishes har der than 5 and softer than 2. Fig. 27 places the 
varnishes in this order. 


Hardness and Abrasion Resistance 81 
a 
Attention is drawn to the obvious need of temperature and 
humidity control of varnish films in any study of their rela- 
tive hardness. It is intended that these factors shall be con- 
trolled in work planned for the near future. The effect of 
varying the thickness of a varnish film should also be studied. 
The swinging beam was designed primarily for the study of 
varnish films, but from some preliminary experiments (the 
data are not shown) it may be possible to adapt this device 
to the study of the relative hardness of varnish resins, either 
in their natural or their ‘‘run’’ condition. In such work it is 
necessary to produce on the resin specimen a polished plane 
surface. 


Preparation of Films for Hardness.—In working with the 
Walker-Steele swinging beam, the writer has experimented 
upon films formed upon various types of surfaces. In the 
first experiments, the varnishes were applied to wood panels 
in three-coat work. After drying the hardness was determined 
with a swinging beam. This method was faulty, inasmuch as 
the wood panels were not absolutely smooth, and the results 
therefore were not concordant. In subsequent tests, glass 
plates were used, the varnishes being flowed and drained in a 
vertical position. The results obtained were not relative, due 
to the fact that. the thickness of the films varied to a great 
extent. It was recognized that thin films upon a hard surface 
would naturally show a very much greater hardness with the 
swinging beam apparatus than thick films upon the same type 
of surface. In a further series of tests, specimens of glass 
about 5 cm. square were selected. Upon these were spread 
with a pipette 14 ce. of varnish. They were allowed to flow 
out and cover the entire plate. The flowing operation was 
aided with the end of the pipette, and none of the varnish 
was allowed to flow off the plate. Difficultv, however, was 
experienced in getting good films. In the final series of experi: 
ments, microscope slides were used. An excess of the varnish 
was placed upon these slides and spun for one minute at 300 
R. P. M. upon the apparatus described on page 108. This 
method produced smooth, even films of more relative thick- 
ness than any other method experimented with. The viscosity 
of the varnish must be taken into consideration, and if the 
directions on page 108 are followed, films of uniform thickness 
for hardness comparisons may be obtained. In carrying on 


82 Hardness and Abrasion Resistance 


this work, the apparatus must be kept in a glass cabinet and 
the varnished panels should be placed in the cabinet for a 
period of time before test so that they will all be brought to 
the same temperature and tested under practically the same 
degree of humidity. This apparatus will give much more 
concordant results if kept in a room maintained at a standard 
temperature and humidity, such as is deseribed on page 131. 


The effect of moisture in reducing the hardness of varnishes 
is quite apparent from the results of some tests which were 
recently made. After the panels were dried for a period of 
four days, the ends were immersed in water for a period of 
18 hours. Immediately after removal from the water, the 
films were pressed to dryness with absorbent filter paper for 
30 seconds, and the harness again determined. The per cent 
loss of hardness, due to the water treatment, is presented 
below: 

TABLE 15.—Hardness 


Swingitig Beam-Time in Seconds 


Per cent 
Film After loss due 
thickness water to water 
Varnish in Microns 1day 4 days treatment absorption 
Be Ss it ice ed 34 107 173 101 42 
Pare e ig 155 210 120 43 
Ais A. 3 94 194 104 46 
bed ae 20 ewe 191 411. 42. 
I. G. ee hyd 30 177 239 137 43 
ate 24 170. 229 137 40 
ES War saeer 26 188 Pee | 120 49 
WARE Ae ne 2 20 52 169 85 50 


Pfund Hardness Meter.—Doubtless one of the most satis- 
factory instruments for determining the hardness of varnishes 


FIGURE 28 
Diagram of Pfund Hardness Meter. 


> 
of 
e 


oe ne 


H ardness and Abrasion Resistance 83 


and lacquers is that recently developed by Pfund. This type 
of apparatus has been in use for over two years in one large 
plant laboratory, and has proved thoroughly reliable for all 
types of surfaces. Even on those surfaces in which the ‘‘top 
tack’’ exists, this apparatus gives results which parallel the 
findings of practical varnish men using the finger nail test. 
The apparatus is described below by Dr. Pfund: 

The general disposition of the apparatus is evident from 
Fig. 28. A brass beam AA is pivoted at P and is supplied 
with a counter-weight at W, which serves to balance the beam 
in the absence of the weights M, M.. Impression on the var- 
nish film V is made by means of a circular cylinder of ecrystal- 
line quartz C of 14-inch diameter. The lower surface is accu- 
rately ground and polished to hemispherical form while the 
upper, flat surface is inclined to the horizontal by 4°. For 
purposes of viewing, a piece of clear glass is mounted at G so 
that a horizontal beam of light (perpendicular to the position 
shown) may be directed downward through the quartz cyl- 
inder where reflection takes place at the hemispherical surface. 
The returning beam enters the microscope 0—the character of 
the phenomenon under observation being shown in the insert 
of Fig. 28. This illuminating device may, of course, be replaced 
by the more compact vertical illuminator attachment for 
microscopes. The diameter of the circle of contact between 
the hemispherical surface C and the varnish film is measured 
with a micrometer eye-piece of magnification 10 x. The actual 
combination used is a Leitz objective No. 2 and the above 
micrometer eye-piece. This combination yields a linear mag- 
nification of 70 diameters. 

Instead of measuring the diameter of the circle of contact 
for a constant load M it has been found that a much greater 
dispersion of results could be obtained by varying the load 
until a cirele of fixed and predetermined diameter was pro- 
duced. The actual diameter agreed upon was three divisions 
in the micrometer eye-piece. Rather than find the exact load 
required, it was found more expedient to put on loads yield- 
ing diameters, respectively, too small and too great. By 
recording both loads and diameters it was possible to deter- 
mine the exact load by simple interpolation. For very hard 
surfaces it was found that the necessary loads become exces- 
sive. Consequently, it is recommended that, for such mate- 
rials, a hemispherical surface of 14-inch diameter be employed. 


84 Hardness and Abrasion Resistance 


Since the speed of drying and, therefore, the hardness, is 
dependent to a marked degree upon the film thickness, it has 
been found necessary to produce films of constant thickness 
by the spinning dise method of Walker and Thompson.* In 
most cases a speed of 450 R. P. M. yielded a satisfactory film. 


Some results obtained for characteristic materials after 
various intervals of drying are given below. The values re- 
corded are the load M (Fig. 1) necessary to produce the circle 
of fixed diameter: 


6hrs. 24hrs. 48 hrs. 1 week 
Oil Vehicle (no gum)........... 6.4 10.6 12.4 
Black Varnish Enamel.:........ 13.0 22.0 43.0 
Bpar “VAINISh! oa oles toe ee 220.0 440.0 650.0 
Black Nitrocellulose Enamel..... 930 grs. 1060.0 1090.0 1375.0 
Clear Nitrocellulose Lacquer... .. 2285.0 2450.0 2685.0 


These results require no comment. It must be pointed out, 
however, that such determinations have meaning only when 
drying and subsequent measurements are carried out in a 
‘constant temperature and humidity room.”’ 


ABRASION RESISTANCE. 


The apparatus which the writer has used for this purpose 
for over twenty years in shown in Fig. 29. It consists of a 
glass tube about six feet long, having an internal bore of 7/8 
inch. This is supported in an upright position over a dish 
holding the panel to be tested, at an angle of 45° to the vertical. 
The abrasive material, consisting of No. 50 emery powder, 
is dropped through the tube through a funnel having a bore 
of 5 mm. When the emery reaches the bottom of the long 
tube, it scatters itself, to strike a surface on the panel about 
an inch in diameter. The emery is constantly poured in until 
the paint coating has worn away, disclosing the bare wood 
or metal. The weight in pounds of emery powder to cause 
disruption of the coating is recorded and reported as the 
measure of abrasion resistance. The test has proved useful 
not only on freshly dried and hardened coatings but also upon 
coatings which have been exposed to the weather for several 
months. Paints, for instance, which chalk rapidly usually 
form soft surfaces, whereas those which remain hard gener- 
ally show a high degree of resistance to abrasion. For experl- 
mental work in the laboratory, the writer has used tin panels 


*Walker and Thompson—Proec, Am. Soc. Testing Mat. (1922), p. 465. 


i Asmat te: 


Hardness and Abrasion Resistance 


--——40 


FiIGuRE 29—Gardner Abrasion Test. 


86 Hardness and Abrasion Resistance 


coated with very thin films of lithographic ink, usually in red. 
Over this colored surface, clear or pigmented products are 
poured or spun to films of the desired thickness. After hard- 
ening, they are tested for abrasion resistance. The underly- 
ing color shows a distinct contrast when the emery has abraded 
the coating down to the colored ink. 


Abrasion Resistance Test of Arsem.—<A testing device 
called the Abrasiometer, for measuring the abrasion resistance 
of varnish films, and which uses numerical values, reproducible 
to 10 per cent or less, has recently been devised by W. C. Arsem 
and originally described in the Scientific Section Circular No. 
2944. A brief description of the apparatus by Arsem, together 
with a chart of some of the results obtained, is given below. 


500 


ABRASION RESISTANCE IN GRAMS 


Z00 


}oO 


FIGURE 30 


Per cent of Gel-Forming Ingredient, by volume. A—Special Bodied Linseed 
Oil. B—Bodied China Wood Oil. C—Cellulose Nitrate. 


Hardness and Abrasion Resistance 87 


The apparatus used in the work consists of a small steel 
ball-bearing 3/16-inch diameter mounted go that a range of 
pressures can be applied to it while it is being moved over 
the surface to be tested. In the simplest form of the apparatus, 
the steel ball is mounted at the end of a pointed wooden rod 
fastened to the right-hand pan of a laboratory trip scale with 
the ball end down, and a counterpoise on the other pan. 


In testing a varnish film, the test plate is placed on the sup- 
port and moved about under the steel ball, gradually increas- 
ing the weights, until a definite barely visible scratch is pro- 
duced. Several further tests are then made, using weights 
both greater and less than the first approximate value, until 
the weight which will just produce a scratch is found. With 
reasonable care, on a film of uniform thickness and degree of 
dryness, the critical pressure can be determined to within 5 
to 10 per cent. 


Since the abrasion resistance of a given sample will depend 
on the degree of dryness, and hence on the initial thickness, it 
is important that uniformity in the thickness of test films be 
secured. 


If varnish is flowed on a flat plate and drained off by stand- 
ing the plate vertically, it is easy with this device to detect a 
variation in resistance from top to bottom, especially during 
the early stages of drying. 


Parlin Abrasion Testing Machine.—The type of abrasion 
testing machine used at the du Pont lacquer plant at Parlin, 
N. J., for determining the abrasion resistance of films is shown 
in Fig. 31. 

It consists essentially of a fixed base equipped with an ad- 
Justable clamp for holding the panel. The carriage, through 
which passes the rubbing tool, is motor driven from behind by 
a rod or piston which moves it back and forth in a horizontal 
plane. <A counter is also fastened to the carriage which records 
the number of oscillations made in rubbing through the lac- 
quer. The tool used is tipped with a rubber or any desired 
mild abrasive. By placing shot in the hollow cylinder at the 
top of the tool, the severity of the test can be varied. 


Method of Testing.—To test a lacquer, clamp the panel in the 
position shown, insert the tool in the carriage and connect the 
motor. With the carriage at one extreme of its path, start 


88 Hardness and Abrasion Resistance | | 


\ 
: 
‘ 
4 
J 
; 


FIGURE 51 


Parlin Abrasion Testing Device. 


the oscillation. When the lacquer has been rubbed through, 
which may be readily seen by the appearance of the panel, note 
the number of oscillations made and disconnect the motor. 
Comparisons may be made as in the previous tests, by using 
coatings of the same thickness. 


CHAPTER IV 


GLOSS MEASUREMENTS ON PAINTS. 


It is important that instruments be available for measuring 
the gloss of paints. One such instrument recently developed 
.is known as the Ingersoll glarimeter. Considerable work has 
been done with this instrument by E. F. Hickson of the Paint 
and Varnish Section of the U. S. Bureau of Standards. His 
results are presented below in the form of a paper originally 
prepared for Scientific Section Circular No. 307. 

‘‘Flat,’’ ‘“egeshell,’’ and ‘‘gloss’’ are terms commonly used 
in describing the surface of a paint coat. Whitewash, flat 


FIGuRE 32 


Ingersoll Glarimeter Resting Upon Disc Coated with White Gloss Paint. 


wall paint, and japan color coats are examples of the so-called 
‘*flat’’ finishes. ‘‘Egegshell’’ finishes are possessed by many 
oil paints, pigmented lacquers, and wall finishes. The best 
grades of enamels are examples of highly glossy finishes. 


90 Gloss Measurements 
 ——————— 

Other than by Nelson* little mention has been made of the 
use of the glarimeter in connection with paint and varnish. 
It is the purpose of this paper to show some of the applications 
and limitations of the glarimeter as an instrument for measur- 
ing the gloss of paints. 

Ingersoll Glarimeter—This instrument was developed by 
L. R. Ingersoll, of the University of Wisconsin, in connection 
with research work on paper problems for the Forest Products 
Laboratory. It was first described by him in 1914,+ and has 
been further described in other places. Its chief use for 
several years has been in the paper industry. 


The glarimeter used in this work is of the latest type,t and 
is shown in Fig. 32. It does not measure gloss directly, but 
gives the ratio of polarized to total light in a certain direction 
from the sample, this ratio being taken as the measure of the 
gloss. The instrument is so built as to allow a beam of hght 
to fall onto the test surface at an angle of 571% degrees, and to 
be reflected into a polarimeter at the same angle. Gloss is 
expressed in angular degrees on an arbitrary seale reading 
from 10 to 60, and is determined by moving the index until the 
two parts of the bifield are just matched in light intensity. 
The gloss in degrees may be converted into per cent gloss by 
Ingersoll’s formula: 

Per cent gloss = 100 X cosine 2 X (60° —scale setting). 


Method of Making Tests——The most satisfactory method for 
preparing films for gloss measurements consists in whirling 
the paint on a glass plate{ and letting the coat dry in a well- 
lighted laboratory for not less than 48 hours (in the lightest 
part of the laboratory). If the paint hides poorly, additional 
coats are spun on the plate until any effect of the background 
is eliminated. The gloss is then measured in several places 
but preferably at the same thickness, five readings being 
taken in each place, and the mean of the results recorded. 
Readings may also be taken on brushed films, but if the brush- 


*Nelson & Schmutz, Proceedings, A. S. T. M., Vol. 24, Part II, p. 923 (1924). 

j Electrical World, Vol. 68, pp. 645-647 (March, 1914). For further references 
see sunrgds No. 100, Central Scientific Company, 460 E. Ohio Street, Chi- 
eago, Ill. . 

tCentral Scientfic Co., Chicago, Ill. 

qP. H. Walker and J. G. Thompson, “Some Physical Properties of Paints,” 
Proceedings, A. 8. T.-M. Vol. 22, Part. II, p. 465 (1922), 


ae vere neeaye 


Gloss Measurements 91 


marks show, the readings taken parallel with these marks will 
be slightly higher than those taken across them. The whirled 
films are smoother than the brushed films. Table 16 giv 
readings by this method on typical white paints and in two 
instances results of whirled films are compared with brushed 
films of linseed oil paints. It is noted that gloss readings on 


these whirled films are shghtly higher than those on the 
brushed films. 


es some 


TABLE 16 
GLoss MEASUREMENTS ON VARIOUS WHITE ParInts 
Gloss 
1—Lead-zine-linseed oil paint Degrees Per cent 
MORN Re ee a Bode nce cn dcke. 50.8 95.0 
Been coat: j0D....... 236s. s.c.... 50.1 94.2 


2—Another lead-zine paint 
Whirled film 


RETR oor ic. s, ass duc ot g Ghee kee CE raw eye 96.0 
Oe, ss eee cee cece n., a 95.5 


SpE MREMORTT Sia vey if one's he gO -s a koe how os 51.2 95.4 
4—Inside “gloss” wall paint 

re ici. Soc cat eee edie cne. 52.5 96.9 
5—White enamel 

ee ls oe bob cela ole. 54.0 97.8 
6—Inside “flat” wall paint 

RE Re ee ee er ee 22.0 24.0 
(—“Eggshell” wall paint 

Rh EM ee ery Oh ei ed ee oes 40.0 76.0 — 
ee eR oe el 18.0 10.0 


Table 17 shows the precision obtained by the same operator 
im measuring the gloss of whirled films of two white linseed- 
oil paints. 

TABLE 17 


PRECISION OBTAINED ON Two WHIRLED PAINTS, 
READINGS OF GLOSS IN DEGREES 


Paint 4H Paint 4D 
50.2 a) a 
50.8 51.8 
50.8 51.6 
50.8 Di.G 
51.0 51.9 
51.0 51.5 
50.5 51.9 
50.9 51.6 
50.8 51.8 
51.0 


—- Mean BLT (96.0% gloss) 
Mean 50.8 (95.0% gloss) 

Table 18 shows the interesting effect of excessively brush- 
ing a flat white wall paint. Flat wall paints should be flowed 
on with the brush as the effect of excessive brushing is to de- 
velop gloss spots. The table also shows the precision obtained 


92 Gloss Measurements 


by different operators on the same brushed flat white wall 
paint. The excessively brushed paint in Table 18 was notice- 
ably more glossy to the eye than the same paint when brushed 


as little as possible. . 
TABLE 18 
EFFECT ON GLOSS OF EXCESSIVELY BRUSHING A “FLAT” WALL PAIntT 
PAINT BRUSHED AS LITTLE AS POSSIBLE 


Operator A Operator B 7 
degrees degrees 
45s ee ee PEPER EL 29.0 
BOB v's eas oe 66 4 0 ens dipiaiaia a ohe oe nn 30.0 
4 eC LM 29.5 
1 Pr a 29.5 
Mean 29.7 (49.0% gloss) Mean 29.5 (48.5% gloss) 
PAINT BRUSHED EXCESSIVELY . 
Operator A Operator B 
degrees degrees 
B25 ove leces vee ce euas aan oe ee 32.0 
BOQ. so cin oo « win 94 9 a. aopib ine gh clas 32.5 
BOB eka a weno kvons ele we ely a ele ene eee a 33.0 
Mean 382.7 (58.0% gloss) Mean 82.5 (57.5% gloss) 


Loss of Gloss of Paints on Exposure-—Generally the first 
signs of weathering of outside white paints is loss of gloss. 


‘ TABLE 19 
Loss oF GLOSS OF OUTSIDE WHITE PAINTS EXPosED ON Woop 
Percentage of gloss after 


Panel i << <<< nny UDG OF 
No. 48 hours i1month 2months 8months 5months paint 
Lea ery cg Woe ets 92.0 86.5 83.5 70.0 63.0 a 
Bis gis 90.0 7.5 SL 72.5 66.5 a 
Le ee aes Pte 2 90.0 76.0 56.0 40.0 30.0 b 
4 ca sins dee 92.0 81.5 70.0 38.5 38.0 b 
Bis ous oS oy eee 90.0 87.5 77.0 65.0 50.0 a 
SEF Cente 2 ees 90.0 80.5 T4.5 70.0 43.5 a 
Bhai dteten ois tap ates 90.0 80.5 76.0 38.5 28.0 b 
Sil aca eae 90.0 80.5 51.5 37.0 31.5 b 
i caib gasket aes 90.0 2.5 80.0 71.5 56.0 a 
LG or ah inte s aa 89.0 80.5 80.0 70.0 50.0 a 
Te wee cee 90.5 70.0 51.5 40.0 35.0 b 
8 he ue tr Ween 88.5 79.5 T4.5 62.5 48.0 a 
DED sieatee ee eae ee 91.5 77.0 50.0 38.5 PEA b 
ie ere Poet Pr merc te 80.5 74.5 66.5 50.0 a 
Reb es ad aie ee 91.5 83.5 67.5 35.0 33.5 b 
Gig eis ia tool men 90.0 83.5 62.5 40.0 35.0 b 
AS wenn Gite eee 89.0 83.5 79.5 67.5 59.0 a 
EB Borie he, 2 aba my 89.0 84.5 77.0 65.0 57.5 a 
UA hed irae SSR 90.0 81.5 51.5 37.0 38.5 b 
Ad aes Wee s cee ye 89.0 77.0 50.0 35.0 ab eesti b 
CWE SP ee Se US $3.5 86.5 76.0 65.0 51.5 a 
BS Aenea ee aie 90.0 85.5 T4.5 64.0 ‘51.5 a 
Ud Cotes FFLkS ahd tees 91.5 78.0 43.0 37.0 34.0 b 
BAS Bes © oieste ctdatok 90.5 76.0 62.5 43.5 38.5 b 
BE NE wie Wis Ong a ee ee 88.0 85.5 74.5 69.0 54.5 a 
v5 Bae Ree ee PB 90.0 87.5 77.0 67.5 51.5 a 


r 
{ 
3 
| 
j 


4 
‘ 


ae eA ee 


Gloss Measurements 93 


In exposure tests this is often recorded by words such as 
peed, = air, ‘*poor,’’ ‘gloss nearly gone,’’ ete. The appli- 
eation of the glarimeter to measuring and recording in num- 
hers the loss of gloss of exposed white paints is shown in Table 
19. These paints were all outside white-linseed oil paints. 
They were applied by brushing three coats on new wood. The 
panels were exposed vertically facing south. All readings in 
this table are expressed in per cent gloss. 


The paints marked ‘‘a’’ in Table 19 were lead-zine paints, 
while those marked ‘‘h’’ were straight white lead. The white 
lead paints showed a greater loss of gloss at the end of the 
five months of exposure. It should be noted that in panel No. 
19 a higher gloss figure was obtained after the fifth month 
than at the end of the third month. This is the point where 
some of the white lead paints (for instance No. 4) began to 
pick up dirt, and after the sixth month a number of the white 
lead paints gave higher gloss readings than those of the pre- 
vious month. The explanation for this is probably that after 
the first rapid loss of gloss on the white lead paints began to 
pick up dirt. This dirt had the effect of decreasing the bright- 
ness of the paint, thus giving a higher gloss reading by the 
instrument. The effect of brightness on gloss as measured 
by the glarimeter will be considered later in this paper. 7 


If the pigment concentration is kept constant, the effect of 
adding linseed oil to the vehicle of a paint is to increase its 
gloss. This is shown in Table 20 for four kinds of white lin- 
seed oil paints. 

TABLE 20 


EFFECT ON GLOSS OF ADDITIONAL OIL IN VEHICLES OF OUTSIDE 
WHITE PAINTS 


Gloss Oil in 

————_————, Pigment vehicle 

Paint Degrees Percent percent per cent 
JSS ees Se er 47.3 90.2 60 66 
ONO Veo E08 ne a 49.4 93.2 60 76 
AOL aly a eg ea a 49.5 93.5 60 85 
(Paint 2 contained 50 per cent lithopone and 50 per cent zinc 

oxide. ) 

LS See ig ge 48.5 92.0 60 66 
Lee a, AN SE ea 49.8 93.8 60 76 
a, nye ke eK oc 50.1 94.1 GO 85 


(Paint 1 contained 50 per cent titanium pigment and 50 per 
cent zine oxide.) 


cee ee a 48.7 92.3 59.5 66 
“os Se ae 50.2 94.2 59.5 76 
Reet MGs rai sha dlv's.3°s 80 ch cca 5 50.9 95.0 59.5 85 


94 Gloss Measurements 


(Paint 3 contained 30 per cent zine oxide and 70 per cent. 
titanium pigment.) 


HEAD iy se dae Sete Reale en ie eee go 49.3 93.1 61 66 
BS as ie a aes Dele a ek ON sere 50.2 94.2 61 76 
BG Pile cen ao elats. Ge eee Wee OR Ceteie o1.4 95.6 61 85 


(Paint 4 contained 50 per cent zine oxide and 50 per cent white 
lead.) 
If the oil in the vehicle is kept constant, increase in pigment 
concentration tends to decrease the gloss of a paint. This is 
shown in paint 5, a white lead paint. 


Gloss Oil in 
——__————, Pigment vehicle 
Paint Degrees Percent percent percent 
sf: RDA eRe Ome at cama ee hacer Mp ol oie AG, 50.8 94.9 70.3 96 
SSIES iva thine ie ve sins See ese aie ee 50.9 95.0 68.3 96 
Rios laracahe ie eae opp ows baat eceeeal eae ee eae 51.3 95.5 64.6 96 


In connection with the gloss of paint 5, it is interesting to note 
that 5C is now, after nearly two years of outdoor exposure, the 
darkest or has picked up the most dirt. Paint 5A is the whitest 
or cleanest. 


Gloss of Colored Paints.—Darkening of a color (including 
white) increases the gloss readings on the glarimeter. This 
darkening reduces the amount of diffusely reflected light, 
while altering to only a minor degree the specularly reflected 
portion. Therefore it is important to point out that results 
obtained by the glarimeter are influenced by the color and 
brightness of the paint. For example, two surfaces of. glass, 
one white and the other black, both ground ‘‘semiflat’’ in the 
same manner gave the following gloss readings: 

White surtate- (v2.5. .oae ees 42 degrees (80.5 per cent gloss) 

Black. surface: sse9 toe 2s ae eee 55 degrees (98.5 per cent gloss) 
A clear glass plate was then placed over these surfaces and 
gloss reading taken: 

White .......c.ccsceccsvce+ +. 040 GepTees (95.6 per cen tmaee 

Black «so. eo ee ee ..09.0 degrees (99.8 per cent gloss) 
Again, a coat of ‘‘flat’’ drop black in japan gave a reading of 
46 degrees (88 per cent), while a ‘‘flat’’ white wall paint that 


looked as ‘‘flat’’ as the black japan gave a reading of 22 de- 


grees (24 per cent). Black enamels that varied considerably in 
gloss to the eye gave the same readings with the glarimeter. 
A coat of olive drab paint with a fairly dull (eggshell) finish 
gave a gloss reading of 55 degrees (98.2 per cent) which in 


the case of white paints indicates an extremely high gloss. 


a ee 


a Eee ee 


we, so at ee ka ‘ 
es. a, ee ee Ok er 


Gloss Measurements 95 


Effect of Brightness on Gloss.—Evidently, from what has 
Just been said, measurements of the same gloss taken on sur- 
faces varying in brightness are not comparable. <A series of 
grays was prepared from a ‘‘flat’’ white wall paint by the 
addition of very small amounts of lampblack. Each paint was 
flowed on a piece of glass so as to obtain the same thickness, 
and then allowed to dry for 24 hours. In all cases the paints 
dried to smooth, ‘‘flat’’ surfaces in about two hours. Gloss 
readings were taken by the glarimeter, and brightness read- 
ings were taken by a Martens photometer (assuming mag 
nesium carbonate block = 100). <A spherical illumination 
chamber designed by Priest was used. With this appara- 
tus the sample and reference white are diffusely illuminated 
and the reflection is measured normal to the surfaces (both 
conditions approximate only). A description of the use of the 
Martens photometer as well as an illustration of this illumina- 
tion chamber is given in Bureau of Standards Technologie 
Paper No. 306, ‘‘A Photometric Method for Measuring the 
Hiding Power of Paints.’’ Also see page 27. The results 


obtained were as follows: 
Gloss readings 


——_——"_ Brightness 


" Degrees Per cent per cent 
Pree ILE DOINE. 5. -siew sos idee os ss 24.0 30 84.4 
“Flat” white paint plus carbon........ 27.5 42 62.0 
ss ib rh ry Dts caaie ee 6 33.0 58.9 28.5 
s . a x 2 gC eee eure 36.5 68 15.7 
“ i fe cs enh athidr ve Seto) (2 7.6 


Thus by decreasing the brightness, the gloss readings in- 
creased, although to the eye there was no appreciable differ- 
ence 1n gloss. 


Conclusions.—The glarimeter, when properly used, gives 
readings that can be checked generally within a few tenths of 
a degree by different operators, and the instrument serves a 
very practical purpose. In the case of white paints where the 
total reflection remains about constant, the only variable being 
the finish, gloss readings are in the proper direction as seen by 
the eye. The same would hold true in the case of grays or 
eolors if the total reflection were kept constant. When the 
total reflection is changed, as in the gray series, the glarimeter 
does not take this reflection change into account and therefore 
the readings do not compare with what the eye sees. Colored 
surfaces act in the same manner. On very glossy enamels 


96 | Gloss Measurements 


(black or white) the glarimeter does not pick out the fine 
distinctions of gloss visible to the unaided eye. The paint 
industry is still in need of an instrument that will give values 
for gloss which are not influenced by color and brightness. 
Such an instrument should also be as sensitive as the unaided 
eye in picking out fine distinctions on very glossy enamels. 
For testing the gloss of clear varnishes, Pfund* claims to have 
developed such an instrument. 


*A.H. Pfund, ‘Tests for Hardness, Gloss, Color and Leveling of Varnishes,” 
Proceedings, American Society for Testing Materials, Vol. XXV, Part II. p. 
392 (1925). 


4 
| 
. 


CHAPTER V 


TENSILE STRENGTH AND ELONGATION 


An apparatus recently devised by the writer and H. GC. Parks 
to determine the tensile strength and elongation of paint, var- 
nish and lacquer films is described herewith. This apparatus, 
which is small in size, compact, and neat in appearance, has 
recently been adopted by several testing laboratories. 


Fig. 33.—View of Gardner-Parks Film Tester on Laboratory table. Note 
white test piece of film near top of column, Film thickness gauge at right. 


One man can operate it successfully. It is driven by a 
small electric motor which plugs directly into any electric light 
socket. The photograph shows the size of the apparatus in 
comparison with that of an operator. The drawing indicates 
how the apparatus was constructed. It will be noted that two 
springs are provided, one for paint and varnish films (ranging 


98 Tensile Strength and Elongation 


from 0 to 500 grams) and one for lacquer films (ranging from 
0 to 2,500 grams). Both springs are carefully calibrated. It 
will also be noted that the scale for determining the percentage 
of elongation ranges from 0 to 100 degrees for any type of film. 


In the photograph, at the right, there is shown a small film 
gauge used to determine the thickness of the film tested, the 
dial of the gauge reading in metric equivalents. The results 
obtained upon testing are always calculated upon the basis of 
the load in kilograms per square centimeter, thus taking care 
of films of varying thickness. _ 

Description of Instrument.—In Fig. 34 (1) is the tubular col- 
umn, (2) a bell-shaped housing, and (3) the base proper which, 
together form the body of the mstrument; (4) is the elevating 
screw which is driven by the sheave wheel (5) through the 
worm (6) and worm wheel (7), the elongated split hub of 
which (8) forms a friction nut on the elevating screw; (9) is a 
handwheel, (10) a yoke which carries the guide rods (11) (only 
one of which appears in the drawings), which slide vertically 
in the yoke (12); also the upper specimen grip (13) and the 
lockserew (14); (15) is a tight collar on the screw, (16) 
the lower specimen grip, (17) a tension rod which has a loose 
sliding placed in the hole in plate (18) fastened to ‘bracket 
(19), which bracket, secured to the tubular column, has tapered 
raceways in which steel balls (20) frictionally engage the ten- 
sion rod; (21) is a latch by means of which the balls may be 
disengaged, (22) is a tension spring which carries at its upper 
end the screwed bracket (23) forming a pointer which reads 
on the double scale (24); (25) is the lower end of tension 
spring which is fastened in the bell housing by the setscrew 
(26) ; (27) is an extensometer of which the upper pointer (28) 
is carried by a sliding bar which is adjustable vertically by 
means of the screw (29) and the compression spring (30), and 
which carries a scale (31) which is read from the lower pointer 
(32) attached to a. rack (33), adjustable vertically by a pinion 
attached to the knurled knob (34). 

Operation of the Instrument.—The lockscrew (14) being 
loosened and the elevating screw being run all the way down 
by means of the handwheel, the sheavewheel belted to the 
motor is caused to rotate, which causes the worm, wormwheel, 
elevating screw and handwheel to rotate but causes no relative 
motion of the specimen grips with respect to their distance 


99 


Tensile Strength and Elongation 


IN 


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At right—Front Elevation of 


Sectional Side Elevation. 


At left 


o4. 


FIG. 


Apparatus. 


100 Tensile Strength and Elongation 


apart. ‘The specimen being clamped in the grips, marked with 
gauge marks, and the extensometer pointers being set thereto, 
the lockscrew is tightened, which locks the handwheel and ele- 
vating screw, causing screw to slip in the friction nut (8) 
thereby elevating yoke (10) carrying the upper grip. The | 
specimen is thereby caused to draw up the lower grip, and 
with it the tension rod and spring, whereby a reading of the 
load is obtainable at any instant, on the double seales (for 
which separate tension springs are provided) and also the ex- 
tension of the specimen, due to said load, which may be read 
directly in percentage of elongation by proper manipulation 
of the extensometer pointers, on scale (31). When the spect- 
men fails, the steel balls (20) lock the tension rod and enable 
the ultimate load to be read at leisure. | 


Film Preparation.—In preparing films for test upon this 
apparatus, two methods may be used. The one in use at this 
laboratory to the greatest extent depends upon the use of mer- 
curvy coated tin plates. Sheets of tin plate 6” x 12” are lightly 
rubbed with mereury until the surface is well amalgamated. 
Excess mercury is rubbed off with a rag. The liquid coating 
material can be sprayed or flowed upon the surface. After 
drying, a knife blade is run around the edge of the coated 
surface to lightly lift the film which is then stripped off in a 
large sheet the size of the panel. For varnish films, drying 
over night is allowed. For paint films, drying for two or 
three days is desirable. For lacquer films, drying for 30 min- 
utes is usually sufficient. When working with the latter pro- 
ducts, it is important that the films be stripped not more than 
an hour after application, otherwise they may dry so hard that 
stripping may become difficult. After the films are removed, 
they are placed between sheets of paper and specimens are cut 
out with test piece die. For this purpose, the specimens are 
placed upon a board to serve as a background for the impact 
of the hammer used for forcing the die through the specimen. 


In another method of film preparation, heavy bond paper is 
used and it is given two coats of flexible glue made by dissolvy- 
ing 5 parts of glue and 1 part of glycerin in 100 parts of water. 
Two coats are usually sufficient to fill the paper and give a 
smooth surface upon which the coating material is applied by 
one of the means mentioned above. After treating, the coated 


Tensile Strength and Elongation 101 


paper is soaked in water for a few minutes until the film be- 
comes loose. it is then stripped off and placed in clean water 
to remove any adherent glue. It is then hung up to dry and 
age before testing. Some results obtained upon lacquer films 
with this type of apparatus are shown on page 144. 


Tensile Strength and Elongation 


102 


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CHAPTER VI 


FILM THICKNESS 


Dried Films.—In determining the thickness of dried paint 
films, the apparatus used in this laboratory is that shown in 
Fig. 33. It is known as the No. 3-A Dial Upright Gauge,* and 
is graduated to .QImm. (See lower right hand corner of 
Fig. 33 on page 97.) The thickness of dried stripped films is 
measured qui¢kly and with a fair degree of accuracy with this 
simple device... When measuring the thickness of films in situ, 
such as those which are dried upon metal panels, the proce- 
dure is to measure the thickness of the coated panel and then 
remove a small amount of the coating with a knife to the bare 
metal. Thickness determinations are then made at this bare 
spot. The difference between the two determinations gives 
the thickness of the film resting upon the metal. 


Wet Films.—For determining the thickness of wet paint 

films, this laboratory has used with fairly satisfactory results 
_ the Pfund paint film gauge. This instrument was developed 
for the purpose of measuring the thickness of wet paint-films. 
. Essentially, the instrument consists of a spherical, convex sur- 
face which is forced through the paint layer. Since the paint 
is a plastic solid whose ‘‘yield value’’ exceeds the existant 
capillary forces, the volume of paint originally in a circular 
dise of section ABCKA is forced into the meniscus AEFGBA. 
If the diameter (D) of the circular paint-spot is measured, and 
if the radius of curvature (R) of the convex surface be known, 
it is found that the thickness (¢) of the original paint-film is 
given by the relation: 

p 

16R° 

The final form given the instrument is shown in Fig 35. A 
convex lens L whose lower surface has a radius of curvature of 
25 em. is mounted in a short tube 7, which slides freely in an 
outer tube T’,. The compression springs S keep the convex sur- 
face out of contact with the paint-film until pressure is ap- 
plied to the top of 71. This instrument is simply rested on a 
painted surface, and the lens is forced down as far as it will 
go. Upon releasing the pressure before removing the gauge, 


jess: 


* Made by B. C. Ames Co., Waltham, Mass. 


104 Film Thickness 


———— 


a circular spot is left on the gauge as well as on the painted 
surface. The diameter of the spot on the gauge is measured 


ee ME in 


(JA RN REDDAEDDSE EES 
TATVIMINIRRASTADSS 
TTVIIRIVAA DSS ESD 

SVS IS 3 8S 


Pfund Film Gauge. 
Mark Left on Painted Surface by Gauge. 
Scale for Measuring Spot on Gauge Lens. 


to 0.1 of a millimetre. If the spot is elliptical, the mean of the 
major and minor axes is determined. <A series of readings on 
at least ten spots, judiciously distributed over a given area, 
yields a fair value of the average thickness of film. By re- 
ferring to the table printed below, the thickness of the paint- 
film in mm. and the number of square feet which would he cov- 
ered by one gallon of paint may be evaluated at once. 


A number of experiments were carried out to check the ac- 
curacy of the paint-film gauge. In each case a known mass 
of paint was spread uniformly over a definite area of plate- 
glass, and the thickness of film was ealeulated in the usual 


Film Thickness ) 105 


manner. Different gauges and thickness of layer were used. 
The results are briefly presented in the following table: 


I if III 1V 
Film thickness (by calculation)......... 0.0444 mm. 0.0402 0.0644 0.0638 
Film thickness (by paint-fllm gauge)... 0.0448 0.0390 0.0652 — 0.0638 


Considering the roughness of the measurements, the agree- 
ment is surprisingly good. Equally satisfactory results were 
obtained on varnish films. The differences between the two 
sets of measurements rarely exceeded 3 per cent. 


Fig. 36 
Pfund Paint Film Gauge 


For testing the accuracy of this instrument, ideal conditions 
exist when the paint is grainless and the underlying surface is 
smooth, flat and non-porous. Using a zinc-oxide linseed-oil 
paint spread upon plate glass it has been found, as previously 
noted, that the paint film gauge yields results which are essen- 
tially correct. However, if the paint is gritty or if the surface 
to be painted is rough, the paint-film gauge will yield film 
thicknesses which are too small. Conversely, if the sub-sur- 
face is soft and yields under the pressure of the convex surface, 
the evaluated film thickness will come out too large. 

Undoubtedly this instrument will be of great service to the 
paint experimenter in working on the physical properties of 
pigments.* Probably its most important application will be 


“Readings on glass made with the Pfund gauge by P. R. Croll, New Jersey 
Zine Co. Research Laboratories as referred to are 1047, 996, 979, 870 and 
930 or an average of 964 as against a true spreading rate of 1009 square 
feet as determined by weight of paint (error 3.5 per cent.) 


106 Film Thickness 
LL 


TABLE 22 


d = Diameter of paint spot on lens (in mm.). 
t = Thickness of paint film (in mm.). 


d t 
In mm. Thickness in mm. Sq. ft. per gal. 

Bike oe ee ee 00225 . seen eee 18,088 

he aie RN cate eat oe 00400 . a...) oF ee 10,175 

PSs ag ea ee res 00625... be ee eae 6,512 

ack, oS coe eee one 00900 oo ucccg sae 4,522 

Tic i hea £01225)... ss hee 3,021 

Bes. Ook Ste oe ea 01600 © 0.0: Gihe ae ee 2,543 

ea 2 inp ae ae 02025 03 ck Se 2,009 
IO Sea a oe 02500 «0°. ss sree eee 1,628 
Wed or seagate, aera 08025... i. 55 ae eee 1,345 
PAG Se epepen ee Medan. A .08600.... 53355 ee 1,130 
IB a ae ee oe O4225 0c ic oe ee 963 
PS Rat ao ni epee 04900... . os sac 830 
LUNG sisi c Wc .05625...55.. 5 22 ee 123 
IOC e eee es ee 06400. v.s% oa ae eee 636 
17 Se ee OT225.. 2 oe 563 
ti. Pere reer ot. O8T00..'.. 2 oa eee 502 
1 es eee .09025 .... ia 5 seen 450 
DN x5 Rick Oy on -10000.5 oo. 407 
pdt Peper ene ere tte ey Sy 11025...3. 2.4 369 
De cok Ak Walaa ee 12100 3. seis ee 336 
7 EN a Te eg 8220... So a ee 307 
DAN einen a ee Ae 14400 ...23 6 Sia ee 282 
BD) 5s he ahaa oe 15625. 5 54520 260 
2G bai sitet Coen .169002...5 14.245 241 
OM ine oes eee ‘18226 U5 ote ee pp’ 
Dc david aN oe 19600 540) 0h ee 207 
QD wiciese: aoace ieee eee 21025 5.08 eee 193 
DOs o5 ies soon eee 22500 23 ste eee 180 
Bei e too pee 20000 . |... + sa ee 158 
D4 sy wlseckcc a otacataene 2000 is oc 5 cela eee 141 
DO 5 ea eae ee eeuaee 2400 6s a 125 
BB: iiss ee ees 36100 3. oo. fae 113 


for gauging the thickness of coatings applied by the spray gun. 
Sprayed films are apt to be very thick unless the application is 
properly controlled. (See Table 23.) 


The instrument is apparently accurate to within 25% of the 
eorrect value when applied to fairly smooth planes. This re- 
sult was arrived at by the present writer* after several hun- 
dred tests upon a large number of paints applied to different 
kinds of surfaces. _ It should, therefore, be of interest to paint- 
ers. 

Some of the factors which make the instrument not wholly 
reliable for measuring the thickness of films on exteriors are 
roughness of wood surfaces, rust spots on metal, slight splint- 
ers or grain effects on wood, coarse particles in paints that are 


*See Circular 132 of the Scientific Section. 


<e 


es 


aed Vln Pre 


Ce ge Ae ne ee eee 


Film Thickness 107 
a a eee od 


TABLE 23—Measurements with Pfund Gauge on Surface Coated with a Spray 
Gun and Hand Brush 


Tests on Wood. Tests on Metal. 
Spreading Spreading 
Rate Rate 
Sq. Ft. per Sq. Ft. per 
Gallon. Gallon. 
Mill White Primer: 
Bier ee hc ccc een 868 1093 
Rr os vc caw cee vce 607 420 
Mill White Flat: 
PORTS VANCED et ee. oo va ce ces 192 1107 
YN os oy ce cr 382 Dot 
Mill White Gloss: 
UNG EGY) 8 ee a 1175 980 
Ue Ue a nr rr 407 352 


Nore :—Sprayed films were quite thick and had excellent hiding properties. 
Hand-brushed films were thin and more transparent. 


not well ground, and yielding of surfaces under the pressure 
applied to the instrument. 

A series of tests was also made to determine the actual ratio 
between spreading rate as calculated by determining the 
weight of a paint and the number of pounds or gallons applied 
to a surface, and the spreading rate as determined by the 
Pfund instrument. The measurements of the Pfund instru- 
ment were made upon the surfaces directly after the applica- 
tion of the paint. In these tests dressed lumber that had been 
primed, and perfectly clean black iron were used. Represen- 
tative results are given herewith: 


Wood. 

Spreading rate estimated from weight of PAID Appled es ace. ae we 815 
Be eU err eye URG BRUCE. we so ie od ce esc cc kk ceevcdiccencc. 1175 
Metal. 

Spreading rate estimated from weight of Haintea polled soe wee Sees 827 
peer tam VO LONd SAUrC.. yi ese obs occ oo cae lace beck. 1037 


In another series of tests the following results were ob- 
tained: 


TABLE 24 
Hand Brushed. 
Actual Spread- 
ing Rate Esti- 
Hand mated from 
Sprayed. Brushed Weight of 
Gauge Test. Gauge Test. Paint Applied. 
Mill White Primer: 
ELECTS Sa ee a Hep Rase 1088 1160 Bed 
See ee 925 1001 1073 
Coen 670 155 885 
Gloss White: 
ey eg eels a cw Sw ole 1370 1068 eats 
NE Me i sie fash one 925 1052 1017 


Re Be se. cS -e onan se 510 686 868 


108 Film Thickness 

a 
In the above tests at least ten measurements were made 

with the Pfund instrument on each test, and the average figure 

used in calculating the thickness of the films. It is of interest 

to note the rather uniform results obtainable in hand-brush 

application, as shown by the measurements below. 


TABLE 25—-Diameter of Spot in Centimeters 


Paint No. 1. Paint. No. 2. Paint No. 3. Paint No. 4. 
1,25 Rol 1.45 1.30 
1.30 Re 1.45 1.25 
E10 90 1.45 pe 4 
gS bt 90 1.40 Lae 
1.05 90 1.45 1.20 
1.05 90 1.40 1.25 


Apparently from the above results, the gauge may either 
overestimate or underestimate the amount of paint applied. 
It is believed, however, that the instrument will be found of 
considerable use in painting work. 


Controlling the Thickness of Films for Testing.—In testing 
films of varnish it is often desirable to prepare films of uni- 
form thickness. For this purpose the author has used the de- 
vice shown in Figure 37.* Briefly, it consists of a horizontal 
table mounted on a spindle and capable of being rotated at 
varying speeds. The panel which is to be coated is first gen- 
erously covered with the varnish and then clamped to the 
table. The table is then rotated at the desired speed and for 
the desired time. Under average conditions an ordinary var- 
nish requires a speed of 300 r. p. m. for 60 seconds to produce 
a film 25 microns in thickness. For viscous products such as 
varnish and lacquers, the thickness is practically uniform over 
the entire film. For plastic products such as paint, the thick- 
ness decreases with the increase in distance from the center of 
rotation.* In order to prepare data for use with the spinning 
table, the following factors involved in the thickness of the 
film were studied; viscosity, percentage of non-volatile, speed 
of spinning and time of spinning. 

For this work there were used five varnishes which varied 
in viscosity and non-volatile content. The determinations of 
film thickness after spinning these varnishes upon metal pan- 
els at varying rates of speed for various periods of time are 
shown in Table 26, column 6. There is also shown in this table, 
column 7, the calculated film thickness, using the special 


*Sward & Gardner, Ind. & Eng. Chem. Vol. 19 (1927. ) 
Walker & Thompson, Proc. A. S. T. M. 22 II, 465 (1922. 


Film Thickness 7 109 


formula recently developed. A comparison of these esti- 
mated thicknesses with the actual thicknesses under these 
varying conditions of speed and time is shown in column 8. 


(CE aa ae er ee ET 
ge ef SU eran 


a 


Fic. 37 


Spinning Device for Making Films of Uniform Thickness 


TABLE 26 


OBSERVED AND CALCULATED FILM THICKNESS 
F=0.4N + V! +3 at 290 R. P. M. and 60 Seconds 
Factors: For 215 RP. M. 1.3 


2 ae ik a 0.8 
tat ECR. it 
hk 0.9 
‘ i i Non- Speed Time Thicknes . 
Varnish es Votatil RP. M.| Secs. | Observed Chita Difference 
; 215 60 26 30 +4 
1 1.4 40 290 60 a 23 Moat oo 
375 Gis rlvioekl o 18 oe 
Spans 315 60 ey) 31 paeeet 
290 30 DIS ek ae 26 ed 
2 0.95 50 290 60 26 24 =% 
move 1-190 23 22 ete 
3 755 C60 22 19 3 
215 60 37 35 = 
E06 iL 30 33 S0 tia ines 
3 1.4 50 290 60 29 27 ae 
290 120 26 24 re 
pe 615 © 60 25 22 =3 
Bee TS Sete 60 60 60 0 
290 30 53 51 Sees 
4 2.2 50 290 60 43 46 ae) 
SOO 1a, ea 80 ae 41 +5 
375 60 39 ay aed 
a 215 60 44 46 43 
5 1.4 70 290 60 35 35 0 
375 60 30 28 =) 


By means of this table, it is possible, within certain limits, 
to predetermine the time and speed of spinning that will pro- 
duce a film of desired thickness. 


CHAPTER VII 
DRYING TIME OF FILMS 


There have been disputes among producers and consumers 
as to the drying time of paints, enamels, oils, and various 
varnish products. Many of these have been due to the fact 
that the method of determining the dryness of a film (touch- 
ing every hour with the finger) has not been well defined, and 
especially to the fact that observations could not be made with 
regularity over the drying period which often occurred late 
at night. 


The fact that drying tests made even under the same condi- 
tions and on the same materials by different operators are not 
apt to agree closely, and that the various stages in the drying 
period are not yet exactly defined, would be indicated by the 
results of a report of sub-Committee IX on Varnish, of the 
American Society for Testing Materials. In this work, var- 
nishes were forwarded to several different operators with the 
following methods for test: 


‘Tests are to be made by pouring the varnish on glass and 
allowing to drain in a vertical position so as to get a flow of 
approximately 6 in. in length. Before starting the test, the 
glass plate, as well as the material, should be brought to the 
temperature at which the test is to be conducted. After the 
varnish is flowed on, touch lightly with the finger at a point 2 
in. from the top at 10-min. intervals until it is perceptibly 
changed from a wet to a sticky condition. Consider this the 
point of ‘‘initial set.’? Continue touching lightly at 20-min. 
intervals until the finger can be drawn lightly over the surface 
without feeling sticky. At this point, the varnish would be 
considered ‘‘dust-free.’? Continue touching at intervals of 
one-half hour until a firm pressure of the finger tip does not 
make a distinct impression. At this point, the varnish would 
be considered ‘‘dried hard.’’ 

‘*Reports received from five operators are given in the fol- 
lowing table:’’ 


Drying Time of Films way 
a aaa a 


TABLE 27 


Gardner Drying Time Meter.—An attempt to overcome some 
of the factors which have militated against uniform results 
in drying, the writer a few years ago Hacsioned an automatic 
drying time meter. This apparatus, which is shown in Fig 38, 


ee eee ee 
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ne == mes 
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\ae 


Fic. ~ 


Diagram of drying time meter with section of stand for film. Later models 
of drum on clock are supported by a lace effect circle of metal rather than 
with wire. 


consisted of an alarm clock device fastened on an upright 
support. Attached to the hour hand of the clock is a very 
hghtly constructed wire wheel covered with a circular drum 


Varnish No. 612 Varnish No. 602 

2 Se Set Dust-Free Hard Set Dust-Free Hard 
ase 
‘d 3 Mini- Maxi- Mini- Maxi Mini- Maxi- Mini- Maxi- Mini- Maxi- Mini- Maxi- 
z by mum mum mum mum mum mum mum mum mum mum mum mum 

Q, 
30 75 min. SAO Hrs oa ae a 75 min. 30 hr 

0 oo 60min. 7 ~*~ 13 hr.'21 hr. 23. hr.30 “ 60 min. Dye fe) i hr; 12. “hrs 23 hr 
remem et. 13° 1116 801g * 30 * 60. * Hee Oia eet Ty ee ay 
90 40.~ * Bi 63."* see Me RS eS AO ae. Smet V2 2s x 
30 20 se 30 “cc 54 “cc 12 “<c 12 “ce 2D ce 20 “e 30 “ce 4% “ce % ce 11% “é 22 “e 
60 30 “e 80 se 544 “é 8 “eé 914 “e 24 “é 30 “e 30 “ce 434 “ee 8144 “é 14 “é 
90 30m = aS 38% “ om ate Ril eee ne Sio50** The “ _ 
30 20 “ce 25 “e 5 “ec 61% se 21 ce 23 ce 10 “ec 25 ce 4\ “ce 5% “e 12 “e 23 “<é 
90 ys hah ies (te Ete ree Ome See VAs ales Res Fuad gah et a Be 


112 Drying Time of Films 

esi anna, ORNS 
formed of light tin plate or of aluminum. ‘The drum is slotted 
to receive the test piece upon which the coating is applied. 
This winds under the mandrel rod at the top of the drum and 
is pressed in contact at that junction with a sheet of soft, light 
tissue paper of the same width as the test piece. Both of these 
are automatically pulled from an adjoining double shelf stand, 
by the action of the clock. Just so long as the coating is wet, 
it will stain the tissue paper at the point of junction, the paper 
adhering quite tenaciously to the tacky film. Just at the point 
of firm setting of the coating, the paper will no longer be 
stained when it comes in contact with the test piece and will 
not adhere thereto during its subsequent journey around the 
drum. 

The test piece developed for this work after a trial of many 
materials, consists of a roll of celluloid moving picture film 
(waste short ends of undeveloped raw stock) that has been 
light struck but not developed. This material was selected 
because of its opacity (white silver coated surface) upon 
which, applied, clear coatings are quite evident. Because of 
its great smoothness of surface, paint and varnish coatings do 
not penetrate it, but dry upon the surface somewhat as they 
would upon glass. Moreover, the solvents usually present in 
paint and varnish apparently do not affect the film, and they 
seem to evaporate in the same time as they would from tin or 
glass. Solvents of the ester type, or acetone-containing sol- 
vents, such as may be used in lacquers, could not be used. 
Moreover, such film is of a standard size and character of 
finish and is obtainable in practically any part of the country 
at a low cost from moving picture firms. 

After the apparatus is set up, it should be standardized by 
applying a coating of paint or varnish to the film and allowing 
it to run for a period of twelve hours. The clock is set at the 
figure 12, at which point the slot for the film will be about 14 
inch beyond the mandrel rod. The length of film pulled 
through over that period is then measured and plotted off into 
twelve sections with sub-divisions if desired. Each section 
will be substantially 114 inches in length, representing one 
hour’s time. For an apparatus that has thus been standard- 
ized, the supply of film to be used therein may then be stamped 
or printed with such divisions as are desired. 

If the drying time of a product is to be determined, which re- 
quires a 24-hour drying period, a length of film not exceeding 


Drying Time of Films 113 
a 
40 inches will generally be found sufficient. It is usual to at- 
tach the film late in the afternoon and to make the reading for 
drying time in the morning, the apparatus running auto- 
matically over night. If the tissue paper at the mandrel rod 
is still being stained, the test is continued. If no stain is 
shown, the AR and tissue are both removed and examined to 
determine point of drying as indicated above. 


In an earlier attempt to construct such an apparatus, one 
with a series of pegs upon a revolving wire wheel, into which 
the slotted moving picture film would be drawn, was designed. 
The pegs were so arranged as to cause an SApSE HE to drop 
sand upon the drying film every hour. The sand would re- 
main adherent to the soft, sticky film. When the coating had 
become dry, the sand would not adhere and would fall off as 
the film continued its downward journey. A fairly sharp line 
of demarcation indicating the drying time was obtained. This 
apparatus, however, aoe ed certain mechanical difficulties that 
were not overcome. 


Atmospheric conditions such as humidity and temperature 
will have a profound influence on the drying time of any 
product. The results obtained one day may not, for instance, 
be thoroughly in accord with those shown another day. It is 
the writer’s idea, therefore, that the main application of this 
apparatus will be for comparative purposes in determining the 
comparative drying time of two products. This could be done 
by using two sets of the apparatus (one constructed with a 
double drum wide enough to accommodate two films would 
probably cause a slowing down of the clock). Another method 
would be to use two small films of approximately one-half inch 
width upon the present size type of drum and apparatus. 
Tests have, however, been made thus far with two sets of ap- 
paratus. A varnish or oil having a known drying time is used 
upon one, and the test coating upon the other. When check 
tests upon the same coatings applied to glass were run at the 
same time, the drying time of the latter as determined by 
touching with the finger, corresponded very closely with the 
results obtained on the apparatus. 


Sanderson Drying Time Meter. A drying time meter based 
upon the above apparatus was subsequently worked out by 
John McE. Sanderson and presented in a paper entitled ‘‘The 
Mechanical Testing and Recording of the Drying Time of 


114 Drying Time of Films 


Paints and Varnishes’”’ before the 1926 convention of the 
American Society for Testing Materials. The clever device 
that he has arranged is described below. 


FIGURE 39 


Sanderson Drying-Time Meter showing Sand Dropping from Cones upon 
Varnished Surfaces. 


‘‘The design of the mechanism for testing has been simpli- 
fied as far as possible. Figure 39 shows this machine arranged 
for comparative testing of two materials although the same 
design has been carried out with three and four disks, and 
machines are being tried out with a still greater number. For 
the variety of materials which it is desirable to test on this 
mechanism, ranging from quick drying varnishes to slow dry- 
ing oils, a range of three speeds of the disks appears sufficient. 
These speeds, one revolution in three hours, once in twelve 
hours, and once in twenty-four hours, are all obtained from 
the same clock movement by a change of gears made before 
the test is started. A fourth speed of one revolution per hour 
or less has been included in some tests to sharply differentiate 
quick drying materials. To satisfactorily obtain this speed, 
however, the use of a separate clock mechanism is required, 
and for the ordinary run of materials, the three speeds men- 
tioned above have been found sufficient. 


Si 


I'he drying-time meter as described above, while giving a 
very satisfactory indication of the time required for a film to 
dry on the surface, gives no indication of the time required for 
initial set nor for the film to dry hard. Our recent work has 
been an effort to adapt the instrument to the testing and re- 
cording of these other two periods. 


 < 


ike - 


Drying Time of Films 115 

—— 
“If a pin point is drawn rapidly across a wet film, the flow- 
ing out of the mark which it leaves gives a fairly accurate indi- 
cation of how the material will flow out when brushed, as the 
pin point acts in a manner quite similar to the individual 
bristles in a brush.* As long as the mark left by the pin point 


FIGURE 40 


Sand Trails Adhering to Varnishes Tested With Sanderson Apparatus. 


will flow out and disappear, the material can still be brushed 
without showing permanent brush marks. When the film 
has set up so that marks from the pin point remain perma- 
nently, it has also reached the stage where it will no longer flow 
out when brushed, sprayed, or dipped. 


‘‘Having determined that this pin scratch method offered 
a satisfactory means of testing initial set, it was compara- 
tively simple to devise an attachment for the drying-time 
meter previously described which would test and record the 
initial set. The figure shows the drying-time meter complete 
with this attachment. A shaft mounted horizontially above 
the outer edge of the coated disks is revolved by a separate 
mechanism at a speed of one revolution per minute. Carried 
on this shaft are radial arms terminating in steel points ar- 
ranged so as to press against the coated disk for a distance 
of about 11% in. from the outer edge. When this test is carried 
out with the disks rotating at a speed of once in three hours, 
the marks made by the steel points are about 0.20 in. apart. 
When this test has been run to completion, that is, after sev- 
eral marks in succession show no indication of ean nee ing, 
the mechanism carrying the points is stopped, the funnels are 
placed in position, filled with sand, and the testing of the time 
of surface drying carried out on the same disks. When the 


*A. H. Pfund, “Tests for Hardness, Gloss, Color and Leveling of Varnishes,” 
Proceedings, Am. Soc. Testing Mats., Vol. 25, Part II, p. 392 “(1925). 


116 Drying Time of Films 


material is thoroughly dry, the test is stopped, and the disks 
brushed off as usual. 


‘“‘The determination of the time of drying-hard has pre- 
sented a more difficult problem than the determination of either 
of the other two transition periods. We have experimented 
along two different lines, and while neither of our methods 
has given very satisfactory results, mention of them may be 
justified as suggestions to other workers on this problem. The 
first method was to roll a heavy wheel on the film as it dried 
and attempt to judge the hardness by the impression which 
it left. The other was to cut the drying film with a razor blade 
held at an angle and attempt to judge the hardness by a micro- 
scopic examination of the edge of the cut. The latter method 
has given results more promising than the former, but has not 
been worked out to a point where it can be depended upon to 
indicate comparative hardness between different films. 


‘“The drying-time meter described is adapted to compara- 
tive tests only. Results obtained on duplicate tests'on the 
Same material at the same time check closely. In order to 
duplicate results at different times and different localities, it 
will be necessary to regulate and standardize on all the condi- 
tions such as heat, light, ventilation, ete., which affect drying. 
It gives a means of study of the effect of various conditions 
which affect drying which we have not previously had and 
seems to be the first step toward standardizing drying tests 
so that we can check a batch of material for drying against 
an absolute standard of results recorded some time in the 
past instead of having to make each test against a standard 
sample.’’ 


A personal communication received from D. V. Gregory 
of the du Pont Experimental Station comments upon the San- 
derson type of apparatus which he has found quite satisfac- 
tory in his work. He had one built which is capable of measur- 
ing the drying time of 20 products simultaneously and which 
has an ultimate capacity of 35 products. Gregory states that 
the end points obtained with this meter do not correspond with 
any of the points usually measured by the practical varnish 
man, but he suggests that the results are comparative and 
have been found very useful. He also states that the so-called 
‘“brush-free’’point falls between ‘‘dust-free’’ and ‘‘tack-free,”’ 


Drying Time of Films 117 


and that the ‘‘tack-free’’ point is probably a measure of free- 
dom from ‘‘top tack.”’ 


Drying Time Comparisons. In some determinations of dry- 
ing time made at this laboratory by the finger test and by 
Sanderson with his meter, interesting results were obtained. 
For purposes of test, synthetic resin and ester gum varnishes 
were prepared. The set-to-touch drying time was taken as 
that time at which no varnish adhered to the finger when the 
film was lightly touched. The dust-free drying time was that 
period when the varnish could be lightly brushed by the finger 
without showing marring of the film. These tests showed no 
well defined relationship between the finger test and the San- 
derson meter test. The long period required for surface dry- 
ing in the Sanderson test is in striking contrast to the values 
with the finger dust-free period. The results are given in the 
table below. 


Camparison of Mechanical and Finger Drying Times 


Set Time —Surface Dry Time— 

Sanderson Sward Sanderson Sward 

Varnish Meter Finger Meter Finger 

1c ee eel Ses: 6 min. 7O min. 30 hrs. 95 min, 
GR A 25 min. 7O min. 8 hrs. 95 min. 
ne oO 21 min. 35 min. 21% hrs. 45 min, 
BeS. ot 16 min. 65 min. 2% hrs. 90 min, 
E. G. 3 16 min. - 80 min. 13 hrs. 100 min, 
E. G. 4 14 min. 40 min. SY hrs. 100 min. 
E. G. 1 20 min. 90 min. 71% hrs. 100 min, 


It would appear that the differences shown might be due to 
films of unequal thickness as obtained by the two operators. 


Effect of Driers upon Viscosity and Color of Varnish. In 
the determining the drying time of a series of varnishes made 
with B.S. synthetic resin and with ester gum, and which con- 
tained varying percentages of different types of driers, some 
interesting results were secured. These results were fully 
reported in Scientific Section Circular No. 301. A table of the 
results, indicating the change of viscosity effected by the 
drier, is presented below. 


118 Drying Time of Films 


en reer eee —————————— 


TABLE 28 
Flowed on glass* 
sek - “eyes 
Actual to dust- 
non- touch free Color 
Drier volatile Viscosity min- min- G-H 
Varnish Percent Metal Percent G-H Potses utes utes Scale 
ice 0.2 5 48.1 D-E 1.15 70 95 if 
A nee feak Se 0.02 ea 50.7 F 1.40 70 95 5 
35. pelts 0.002 Co 50.8 EF 1355 70 100 5 
7) 2 ee Cae 0.5 Pb 50.6 G 1.65 70 95 5 
S-Bo.os Re 0.2 Pio 49.8 G 1.65 90 100 5 
soe ew beet ao 0.2 Mn 555 G-H 1.85 90 100 7 
0.005 Co 
EU Face ay a 0.05 Mn 50.8 G 1.65 75 90 6 
0.2 Pb 
0.005 Co 
$-B..5. RR. 0.005 Mn 50.3 E 1:25 70 95 5 
0.02 Pb 
9-B- SR, 0.2 Mn ee F-G 1.55 35 45 7 
0.5 Pb 
10-B. S. R. 0.08 Mn 51.3 G 1.65 70 05 EG 
0.2 Pb 
0.005 Co 
11-BaS 0.05 Mn 50.9 G 1.65 65 90 6 
0.5 Pb 
12-Booo kk None 49.1 F 1.40 70 95 5 
1-E. G. 0.2 Co 49.5 C22 0.95 80 100 8 
2-E A. 0.02 Co 49.5 F 1.40 75 95 6 
Sali G, 0.002 Co 48.7 F 1.40 80 100 6 
4-H A, 0.5 Pb 50.4 F 1.40 40 100 6 
SB: 0.2 Pb 50.1 F 1.40 100 120 6 
6-E. G. 0.2 Mn 51.6 G 1.65 80 100 8 
0.005 Co 
f oS Ones Os 0.05 Mn 53-3 G 1.65 85 100 7s 
0.02 Pb 
0.005 Co 
8-E 0.005 Mn 49.6 F 1.40 85 100 6 
0.02 Pb 
9.fG. 0.2 Mn Siz F-G 135 90 100 9 
0.5 Pb 
10-E. G. 0.08 Mn nN) G 1.65 90 100 8 
0.2 Pb 
0.005 Co 
11-EG. 0.05 Mn 53.4 F 1.40 90 100 7 
0.5 Pb 
12-EoG: None 49.4 D-E its 95 100 6 


Driers in Varnish Affect Physical Properties.—Some results 
of a study of various driers in a large number of varnishes 


gave the following indications: 


* Many of these varnishes, when brushed on a surface would set to touch in 15 
to 30 minutes. With “flowed” films, the thickness is very much greater, and a 


much longer period is necessary. 


Drying Time of Films 119 


1. The kind and concentration of drier has an influence on 
the properties of a varnish. 


2. It is even possible to prepare some types of varnishes 
without driers. They will set and surface dry in about the 
Same time as similar varnishes containing driers, but may 
attain their final hardness more slowly. Varnishes free from 
drier might be suggested for exterior purposes, but it is ques- 
tionable whether this would apply for such varnishes as may 
be used upon floors where hard drying is required. 


3. Large amounts of any kind of drier do not accelerate the 
drying of a varnish to any marked extent. On the other hand, 
large amounts of driers may reduce the resistance of the film 
to saponification by alkali, and tend to make the films more 
brittle. | 


4. Lead or cobalt driers reduce the elasticity of varnish films 
less than manganese driers. The two former types are there- 
fore indicated for spar varnishes which must meet elasticity 
requirements. 


9. Neither lead nor cobalt driers produce skinning of stored 
varnish as rapidly as manganese driers. 


Ozone Apparatus for Drying Insulating Varnishes.—Ozone 
has been used to advantage in the drying of insulating var- 
nishes by Spence and Cochrane.* The apparatus used by them 
is shown in Fig. 41. Tests made to determine the insulating 
properties and absorption of moisture of films when air baked 
are given in a table in that paper. A summary of their work 
would indicate the following: A process has been developed 
for using ozonized air in the baking of typical insulating var- 
nishes. A saving of 50 per cent of the time usually necessary 
in the air baking process has been demonstrated. The films 
thus produced are of equally good electrical properties as air 
baked films and the water resistance of the films equal to that 
of air baked films. The acidity of the films is not increased 
by the ozone treatment. The films baked just to dryness in 
ozone are equal in heat resistance to air baked varnishes. 

Testing the Drying Time of Coatings under Colored Light. 
In some experiments made by the writer, eight open top boxes 


*“The Utilization of Ozone in the Drying of Insulating Varnishes,” by 
EK. B. Spencer and L. U. Cochrane. Scien. Sec. Cire. No. 290. 


120 Drying Time of Films 

———— 
of rather porous cardboard were constructed, approximately 
six inches square and about one inch deep. The boxes were 
inverted, so that when placed on the table a small dark cabinet 
was made. In placing these boxes on the table, they were 
raised sufficiently to allow the free passage of air. In all but 


FIGURE 41 


Apparatus for the production and analysis of ozonized air. 


one of these boxes, which was left for a dark cabinet, a hole 
four inches square was cut in the top. In one of these the 
hole was left without a cover glass, but in the remainder a 
cover glass was used. These cover glasses were of transpar- 
ent glass in red, green, blue and yellow, while two were of 
colorless glass, one plain and the other opaque ground glass. 
The hight was passed through these glasses onto a thin film of 


raw linseed oil spread over a glass slide about four inches 
square. 


iS ee 


Drying Time of Films 121 


snes 


The boxes were placed in the window exposed on the south- 
ern side, where they received direct sunlight. All exposures 
were within the laboratory, which was maintained at a tem- 
perature of about 70° F. 


Box 
Box 
Box 
Box 
Box 
Box 
Box 
Box 


SOUTHERN EXPOSURE (Direct Sunlight) 
Raw Linseed Oil. 


RSE The SUE a ST a Eh a) Wet as when put in after 4 days 
Matienole but without class. ...........'. Dry in 2 days 
BViCNe ial -lASS COVES... 5. ce ee cc Dry in 2 days 
Merten Class COVEY... ... sos chee one Dry in 2 days 
CU IASS COVER. oo uc s cc lace oe ee os Dry in 3 days 
Syitieomiper S1ASs COVEr... 6... ce ee Dry in 2 days 
MaitineniMere lass “COVE? .. eis. ee oe ek ee Dry in 8 days 
Mitiieereen Class COvVer.,.......2..6600. Dry in 3 days 


Experiments discontinued after 4 days. 


The word “dry” refers to condition of dryness to touch but not fully hard. 


This subject has been briefly treated in Scientific Section 
Circular No. 172 in which there is an abstract of work that 
has been done in various places. 


CHAPTER VIII 
TEMPERATURE AND HUMIDITY CONTROL CABINETS 


In the preceding chapter, the difficulties of obtaining uni- 
form drying time results in various laboratories are discussed. 
Similarly, check results cannot be obtained in determining the 
tensile strength and elongation of paint and varnish films un- 
less the test specimens are first aged in a cabinet having the 
desired humidity. As indicating the importance of building in 
a paint laboratory a constant humidity room, there are given 
below the results on the hardness of four different varnishes, 
as determined by the Pfund hardness tester, under three dif- 
ferent conditions of temperature and humidity. Tests made 
in an ordinary room on one day cannot be compared with tests 
made a few months later under different temperature and 
humidity conditions. With standard temperature and humid- 
ity, however, comparable results may be obtained. The tests 
referred to below were made by Gregory on films which had 
dried for one week at 77° F. and 50% relative humidity. 


Wis as 3 98° F. 98° F. 

50% R.H. 50% R. H. 25% Bo. 
G gal, rosin-wood oll. varnish:s ose ee 1300 170 950 
6 “ ester gum-wood oil varnish......... 13800 270 850 
6 “ zine resinate-wood oil varnish...... 2600 1750 1840 
6 “ limed rosin-wood oil varnish....... 1450 1150 1350 


The above figures represent the number of grams necessary 
to produce a definite circle of contact between the ball bearing 
and the varnish surface. 


From time to time laboratories have devised small cabinets 
arranged with heating and humidifying devices. Some of the 
work that has been done in this connection is outlined below. 
Special attention should be drawn to the latter section which 
deals with the Walker type of humidity room. Correspond- 
ence with the Research Division of The New Jersey Zine Co. 
at Palmerton, Pa., elicited information regarding a small cabi- 
net which they have constructed and which is shown in Fig. 42. 
A description of this cabinet is given below. 


_ Palmerton Cabinet.—‘‘We have gotten along, after a fash- 
lon, by using small cabinets which are maintained at room 
temperature or slightly above, for which the constant humid- 
ity has been provided by passing air through sulphurie acid 


120 


Temperature and Humidity Control 


‘SoTO}BIOGVT “OD ouIZ “f ‘N sq pasg JouTqro 
CF AVON 
Ulf HYE{O/ Of 1OJOY/ 


SAGUIEYD UNE 
Of JOGUILY: 
"bunlajem 
wod, bur 


peal Sf10q 


*0OS 7H ANI 
WeUO) sHyog 


An aul7 
AY sfaaye” Ol 
payeulebyet 


SOWA {Uf 


a 
SOIWIAXT JOWMAAY 


ma, do, May {U01/ 
fauige) Ajiplunp/ pue ainpesadulay {Ue{SUOD fauige7 Kyipiuinyy pue ainjesadilal JUe{SUOF 


124 Temperature and Humidity Control 


of a definite specific gravity. Tables showing the specific 
eravity of sulphuric acid necessary to maintain any specified 
humidity at a certain temperature, have been published by 
Wilson and will be found in the Journal of Industrial and 
Engineering Chemistry, Volume 13, No. 4. In applying this, 
we use the ordinary laboratory air supply and pass the air 
through a series of at least three liter bottles; the first one of 
which (that is, the one nearest the air line) is changed at least 
every twenty four hours, and the other two moved up, while 
the third, or last, bottle is replaced by one containing sulphuric 
acid of exactly ays required concentration. This scheme, of 
course, has its disadvantages as it is necessary to test the vate 
tion daily and the volume of air that can be passed through is 
rather limited. However, we find that it works very well 
within the limits of its capacity.” | 


Correspondence with F. P. Veitch, Chemist in Charge of 
Naval Stores Investigations, of the Bureau of Chemistry, U. 
S. Department of Agriculture, referred to the constant tem- 
perature and humidity room which is used at the Bureau of 
Chemistry. It apparently contains rather expensive equip- 
ment. The reference is as follows: 


Bureau of Chemistry Cabinet.—‘‘This room is described in 
an article entitled ‘A Constant Temperature and Humidity 
Room for the Testing of Paper, Textiles, ete.,’ which was pub- 
lished in the January, 1918, issue of the Journal of Industrial 
and Engineering Chemistry, page 38. 


“The hygrostat control used in our room is manufactured 
by the Carrier Engineering Corporation, Land Title Building, 
Philadelphia, and is catalogued as Type F. The thermostat 
shown in the illustration is manufactured by The Powers Regu- 
lator Co., 101 Park Avenue, New York, N. Y. We have 
recently replaced this thermostat with the Tycos Type-P tem- 
perature regulator (reverse action), manufactured by the Tay- 
lor Instrument Companies, Rochester, N. Y. This is the only 
change we have made in our room since the publication of its 
description.’’ 


Correspondence with the Bureau of Standards in regard to 
the drying cabinet in the Ceramic Division, the humidity room 
in the Textile Division, and the air conditioning equipment 
in the Paper Testing Section, is abstracted below. 


a 


Temperature and Humidity Control B25 


FIGuRE 43 
Electrically Controlled Moist Cabinet With Recording Gauges for 
Drying Painted Panels. (Gardner Laboratory.) 


FIGURE 44 


Ventilated Moist Cabinet for Studying Drying Time of Oils and Varnishes. 
(Gardner Laboratory. ) 


126 Temperature and Humidity Control 


Textile Division Cabinet.—‘‘ A description of a Carrier Dry- 
ing Cabinet used by our Ceramic Division was published in 
the November, 1925, issue of the Journal of the American Cer- 
amic Society, page 691. This cabinet is one of various types 
and sizes manufactured by the Carrier Engineering Corpora- 
tion. The following equipment is used in the textile section. 

‘‘ Mir conditioning Equipment: : 

‘Ammonia compressor, 714 tons capacity; Automatic Re- 
frigerating Company, Hartford, Conn. 

‘Carrier Humidifying System; Carrier Engineering Com- 
pany, 1402 Land Title Building, Philadelphia, Pa. 

‘‘Tyeos Wet and-Dry Bulb Thermometer Recorder; Taylor 
Instrument Company, Rochester, N. Y. 

‘Hor very accurate determination of humidity, Fuess As- 
perator, Kreuger and Toll Corporation, Engineering Building, 
114-118 Liberty Street, New York City. The Comins Electro- 
Psychrometer, American Moistening Company, 52 Chancey 
Street, Boston, Mass., is considered equally suitable. 

‘‘Size of Room, 45 x 30 x 12 feet. 


‘¢ Automatic Control— Ammonia refrigeration is used during 
warm weather and steam during cold weather to obtain the 
desired temperature. The atmospheric conditions are auto- 
matically controlled within + 3 per cent of 65 per cent relative 
humidity and within + 3° F, of 70° EF. temperature. ”’ 

Air Conditioning Equipment of Paper Section. ‘‘An air 
conditioning and testing cabinet is being developed by the 
Paper Section for use in making tests of physical properties 
of paper. The air is conditioned by drawing it through a sul- 
phurie acid solution of the correct concentration to give the 
desired humidity in the cabinet. The testing instrument is 
placed inside the cabinet and by means of rubber gloves pro- 
vided with flexible sleeves, the test specimens are manipulated 
from outside the cabinet, thus obviating the necessity of open- 
ing it. No means have been provided for controlling tempera- 
ture as this has been found unnecessary in testing paper. 

Correspondence with the Forest Products Laboratory, U. S. 
Department of Agriculture, at Madison, Wis., resulted in the 
receipt of a very interesting report entitled ‘‘ Automatie Regu- 
lation of Humidity in Factories,’’ by A. C. Knauss, Engineer 
in Forest Products. This report which is bound and which 
contains 16 pages and several illustrations, will probably be 
of considerable interest to those contemplating the use of 
‘humidity in factory control work. One of the illustrations in 
the article is reproduced below, by permission, as Fig. 45. 


Sg ee a ees 


127 


Temperature and Humidity Control 


’ 

3 

SHIWOWSIY {Ul0y Ke NG 

\ si aes 


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BAlOA Buixtp/ 


CYA VoSsipOW/ 
hs0jOs0go7 ‘Ynposy {63/04 @) AbBazw 


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0 fuawabuossy 


LING JS 


bur JOOIAMALO/Y: ote 
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resulted in information regarding a type of 
000. . 


) 


Figure 45 


? 


Correspondence with the Materials Section, U.S. Navy Yard 


Brooklyn, N. Y. 


apparatus constructed during 1919 at a price of about $4 


A description of the apparatus is given below. 


128 Temperature and Humidity Control 


Navy Yard Cabinet. ‘‘The room in which the conditioned 
air is discharged from the apparatus is about 8 ft. x 11 ft. and 
9 ft. high. It is completely insulated on all sides, roof and 
floor with 2 in. of compressed cork covered on ceiling and walls 
with 1% in. of Portland cement. 

‘The air in the above room is maintained at a temperature 
of 70° F. + 1° and at a relative humidity of 65% + 2% by the 
following processes. 

‘¢ Air is taken from outside of the above room at any tem- 
perature and humidity within the capacity of the apparatus 
and drawn by a suction fan into a large sheet metal spray 
chamber. 

“The air is drawn through a curtain of whirling water 
which is maintained at a low temperature by flowing over a 
bank of Bandulot ammonia coils forming part of a two ton ice 
machine. 

““The water is recooled through recirculation over the coils 
by means of a motor driven centrifugal pump. 

“The air passing through the water in the spray chamber 
is cleansed and reduced in temperature to that of the cooling 
water at which temperature the air is 100 per cent saturated 
and is mixed with entrained moisture. 

‘The air then passes over a Vento steam coil to which steam 
is admitted through thermostatic control and then passes 
through a chamber containing moisture eliminators which re- 
move all the entrained water present other than in vapor form. 

‘After leaving the moisture eliminators the air passes over 
the stem of a thermostat which is so set as to admit and cut 
off steam to and from the above Vento heating coil which heats 
the air to a constant temperature at the thermostat of 57° F. 
at which temperature the air contains 100 per cent humidity or 
.7464 lbs. of moisture per 1000 cu. ft, of mixture of air and 
moisture. 

‘The air then passes over a second set of Vento heating 
coils which further raises the temperature and thus reduces 
the relative humidity. It does not matter how high it is heated 
provided that after passing the heater, it reaches the room 
at the required temperature of 70° F. A thermostat in the 
room controls the steam admission to the second set of heating 
coils and is set at such a point that the air always is reduced to 
the desired constant room temperature from that which it has 
after passing over the heating coil. 

‘‘The humidity as stated above drops after passing over 
the second set of coils from 100 per cent saturation to a per- 
centage corresponding to the dry temperature of the air after 
it passes over the second heater. As the air cools after passing 


Temperature and Humidity Control 129 


over the second heater the relative humidity increases to that 
corresponding to a dry temperature of 70° FE. This will be 
65 per cent relative humidity if the absolute humidity of the 
air as it passes over the thermostat in the eliminator chamber 
is .7464 lbs. per 1000/cu. ft. at 56-57° F. saturation. 

‘To summarize the atmospheric conditions in relation to 
that existing outside the conditioning room and that inside 
the room: 

‘“(a) Inside the room, a constant temperature of 70° F. and 
a constant relative humidity of 65 per cent requires a constant 
absolute humidity of .7464 Ibs. per 1000/cu. ft. of mixture of 
moisture and air. 

‘“(b) To produce air containing .7464 lbs. per 1000/eu. ft. 
requires that the outside air shall be passed through a water 
spray the temperature of which is 57° F. At this temperature 
the air assumes a relative humidity of 100 per cent and con- 
tains .7464 lbs. per 1000 cu. ft. of moisture. 

‘“(c) By heating the saturated air (100 per cent humidity— 
o/° F. dry, wet and dew point temperatures) so that it has a 
dry temperature of 70° F., dry bulb, the relative humidity 
drops from 100 per cent to 65 per cent, and the wet bulb then 
rises from 57° to 62° F. the absolute humidity remaining the 
same as before—.7464 lbs. per 1000 cu. ft. 

‘‘From the above it is readily seen how air at any tempera- 
ture and humidity (within the limits of the apparatus) can 
be transformed into air having a constant dry temperature of 
70° F. and a constant relative humidity of 65 per cent. 

‘The air conditioning room in the Laboratory Section is 
capable of performing the following: 

‘‘(a) Washes and cleanses the air delivered to the testing 
room during all seasons of the year. 

‘“‘(b) Cools the testing room in summer to a temperature 
of 70° or less in weather of not exceeding 95° F. dry bulb or 
78° F. wet bulb temperature. 

‘“(c) Heats the room to a temperature of 70° F. or more in 
weather of 0° F. or less. 

‘“(d) Maintains not less than 65 per cent humidity in the 
room during all seasons of the year without regard to the 
outside weather conditions within the above limits. 

‘“‘(e) Automatically controls the dampers and valves con- 
nected with the room control between full-open and full-closed 
with a variation in relative humidity of 4 per cent or less. 

‘“(f) Automatically controls the dampers and valves con- 
nected with the room temperature control between full-open 
and full-closed with a variation in temperature of 2° or less. 


130 Temperature and Humidity Control 


‘“(@) Provides copious and continuous ventilation to the 
room during all seasons of the year. 

‘‘Permanent records are maintained of the atmospheric con- 
dition in the room by means of a recording wet and dry bulb 
thermometer from which the relative humidity is readily 
determined.’’ 

Walker Apparatus—tThe type of humidity room devised 
by Walker, Steele and Hickson of the Bureau of Standards 
and originally described by them in Scientific Section Cireular 
No. 310 is given below. The apparatus shown was built in the 
paint and varnish testing laboratory of the Bureau of Stand- 
ards for maintaining accurate control of temperature and hu- 
midity where paint films are tested. The room which is of ex- 
tremely simple construction is kept at constant humidity by 
blowing air over a saturated solution of magnesium chloride. 
The temperature is also maintained within close limits by a 
simple device. It is understood that this room, which is large 
enough for several testing instruments and which will accom- 
modate one or two operators, was constructed at a cost of 
about $600.00. Their description follows: 

‘While definite conditions of humidity and temperature are 
at least desirable if not necessary in testing the time of dry- 
ing of paint, varnish, ete., and in making physical tests on films 
of such materials, there is no reason other than convenience 
for deciding just what these definite conditions should be. At 
30° C. (86° F.) and 32 per cent saturation an operator experi- 
ences no serious discomfort and since there are very few days 
in the year when the indoor temperature is any higher than 
30° C. this temperature can be maintained in most places with- 
out using refrigeration. Saturation of 32 per cent is easily 
and cheaply maintained by using a saturated solution of 
MegCl.6H.O. It is therefore suggested that where standard 
conditions are necessary or desirable 30° + 2° C. and 352 
+ 4 per cent saturation be used as standard conditions of 
temperature and humidity in all testing and research work 
on paint, varnish, and similar materials.’’ 

International Critical Tables, Vol. 1, pp. 67-68, give informa- 
tion as to the percentage saturation of air in contact with 
saturated solutions of a large number of salts. This percent- 
age saturation for many salts varies only slightly with changes 
in temperature. For example, the above authority gives the 
following extreme ranges of per cent, saturation CaCl.2H.O 
90° to 160° C. 16 to 18 per cent, CaCl.6H20 10° to 24.5° C. 38 
to 31 per cent, MgCl6H2O 10° to 50° C. 35 to 31 per cent, 


Lemperature and Humidity Control 131 


Mg (NOs)2 6H20 18.5° to 24.5° C. 52 to 56 per cent, NaCl 0° to 
110° C. 78 to 73 per cent. 


_In looking over these figures it seemed to the writers that 
it would be a very simple matter to maintain a constant per- 
centage saturation by passing a stream of air through a wash 
bottle containing a suitable saturated solution with some of 
the undissolved crystals and then passing the air into any con- 
venient vessel, for example, a bell jar. Experiments with this 


Figure 46 


View of Constant Temperature and Humidity Room Constructed in Paint 
and Varnish Section of Bureau of Standards at Cost of Approximately $600. 


type of set-up gave percentage saturations in the bell jar 
that varied widely and were not what would be expected from 
the data given in International Critical Tables. The reason 
for this failure is not hard to understand when one considers 


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Temperature and Humidity Control 133 


the large difference in the amount of water vapor in saturated 
air at different temperatures and the latent heat of water and 
the heat of solution of various salts. The weight in grams of 
the aqueous vapor in a cubic meter of saturated air varies 
fotebeit esate lo. ©. to 39.187 at 35° C. If air is given a 
definite relative humidity at say 17° C. and then raised in 
temperature to 18° the relative humidity will be about 94 per 
cent of what it was at 17° C.; and if it is cooled to 16° C. its 
relative humidity will be about 106 per cent of what it was 
Grakc ©. | 


If air is passed into a solution having a vapor pressure 
greater than the partial pressure of the water vapor in the 
air, water is taken up by the air and the solution is cooled 
by evaporation. If the vapor pressure of the solution is less 
than that of the air introduced, water is condensed and its 
latent heat raises the temperature of the solution. The heat 
of solution of the salt which dissolves or is precipitated in the 
two cases respectively is also a factor. 


It follows from the above that it is very much simpler to 
maintain a given lot of air in a confined space at a fixed rela- 
tive humidity by means of saturated salt solutions than it is to 
condition a continuous stream of air flowing from outdoors 
or the room into a chamber. 


It is important to have the walls of a humidity chamber 
made of non-absorbent material, and if a fixed temperature is 
to be maintained they should be well insulated. 


Experiments with a metal lined box 75 em. deep, 75 cm. 
long, and 40 em. wide provided with a tight top show that it 
ean be easily maintained at almost any desired humidity by 
directing the air from a very small (5 em.) electric fan (2500 
r. p.m.) placed in the bottom of the box across the surface 
of a saturated solution of a suitable salt in a photographic 
tray or crystallizing dish. With the fan and motor in the box 
the temperature is a few degrees above that of the room, but 
since the solution has the temperature of the air in the box the 
relative humidity remains constant. When low humidity only 
is required, this simple set-up is entirely satisfactory and can 
be run continuously. With very high humidity the motor 
might be ruined and under such conditions it is best to put the 
motor outside the box with the shaft passing through to the 
fan on the inside. 


134 Temperature and Humidity Control 


With this apparatus the specified humidity ean be attained 
in about 30 minutes and maintained thereafter. The follow-. 
ing humidities were shown by a recording hair hygrometer 
calibrated by wet and dry bulb for the humidity range covered. 
No deviation from the average greater than one per cent was 
recorded during 24 hours. 

TABLE 29 


Humidities Observed With Box Apparatus Using Several Salt Solutions 
Humidity Time after closing Humidity in 


in room box to reach de- box 
Humidifying agent per cent sired saturation per cent 
Saturated soln. MgCl6H.O......:.... 30 30 min. 32 
pacturated soln, (atLen 0 ous 39 380 min. 30 
Saturated soln. Mg(NO,).6H,O...... ot 15 min. 53 
saturated ‘soln... Ne@h 06. 65 wee 41 45 min. 77 
Wels oun eaietooo ee ee ee eee Ps) 30 min. 100 


A glass cabinet of about the same dimensions as the box 
described above but having a sliding door on one side (very 
similar to a large balance case) has been found convenient 
where exposure to hght under definite humidity conditions is 
desired. With such a cabinet it is advisable to connect a re- 
sistance in series with the motor so as to run the fan at a low 
speed. <A strong current forces considerable air through the 
openings around the sliding door resulting in too much inter- 
change between the air of the room and the cabinet, and the 
heat from the motor raises the temperature more when the 
fan is running at full speed, so that on opening the door there 
is a greater fluctuation of humidity than when the fan is run- 
ning at say 800 r. p.m. With the fan running at full speed, 
room humidity 36 per cent and Mg(NOs)26H.O in the cabinet 
the humidity in 30 minutes rose to 50 per cent and remained 
there for 90 minutes. On allowing the door to remain open 
for about one minute, the humidity dropped to 47 per cent and 
in 15 minutes after closing it had gone up to 51 per cent, re- 
mained at 51 per cent for 214 hours then gradually rose during 
the next 90 minutes to 54 per cent and remained between 53 
per cent and 55 per cent from 4.00 p. m. to 9.00 a. m. 


Figure 47 gives the design and specifications for a metal- 
lined insulated cabinet large enough for a man to work in, 
which is in use at the Bureau of Standards. This room is 
maintained at 30° C. so that it can be used practically the year 
round without artificial cooling. The relative humidity is 
kept at about 32 per cent. The temperature is controlled by a 
small electric heating coil regulated by a thermostat. <A 20 


Temperature and Humidity Control ri5 


x 20 inch photographie tray containing about 10 pounds of 
MgCl.6H.O and enough water to dissolve about half of the 
salt is placed on the floor and the draft from an ordinary 
electric fan played across the surface of the liquid. With 
the precaution of opening only one door at a time on entering 
or leaving the room the humidity can be maintained at 32 per 
cent saturation and the temperature at 30° C. within the limits 
shown below. 

A sample record taken on February 2, 1927, from 10.00 a. m. 
to 4.00 p. m. with fan and heater in operation showed a rela- 
tive humidity of 32 + 0.5 per cent, and a temperature between 
30° and 30.5° C. During part of this time one man was in the 
eabinet. At 4.30 p. m. the fan and heater were shut off; the 
humidity recorder remained constant at 32 + 0.5 per cent until 
9.30 a. m. on February 38. The temperature was not taken 
after 4.00 p.m. on February 2. 


Another record was made on February 14 and 15, 1927. 
The temperature remained between 30° and 30.5° C. from 12 m. 
to 4.30 p. m. A man entered the room several times during 
this period and remained in it for about 214 hours. At 4.30 
p. m. the fan and heating coil were shut off. At 9.30 a. m. on 
February 15, 1927, the temperature was 22° C. The humidity 
remained constant at 31+ 1 per cent for the entire time (12:00 
m. on February 14 to 9.30 a.m. on February 15). The humid- 
ity and temperature in the room in which the cabinet is located 
varied between 34 per cent at 23.3° C. and 40 per cent at 18.9° 
. 

It is advisable to stir the mixture of MgCl.6H.O crystals 
and solution at least once every day. 

This insulated cabinet has not been operated in warm humid 
weather, and it may be found convenient under such condi- 
tions on starting the operation to first reduce the humidity to 
about 32 per cent by blowing the air over dry CaCl, and then 
remove the CaCl. and replace the MgCl.6H.O mixture. 


CHAPTER IX 
SPECIFIC GRAVITY DETERMINATIONS 


A method worked out in this laboratory for the determina- 
tion of the specific gravity of paint pigments was later adopted 
with some modifications by the American Society for Testing 
Materials. This original method which appeared in an early 
edition of this volume is now replaced by the standard methods 
of test which are given below. 


A. S. T. M. STANDARD METHOD OF TEST FOR SPECIFIC 
GRAVITY OF PIGMENTS 
Issued As Tentative, 1923; Adopted, 1924. Revised 1927. Method A: For 
Routine Testing of Several Samples Simultaneously, | 
I APPARATUS 

1. The apparatus shall consist of the following: 

(a) A pyknometer as shown in Fig. 48 (a) or (0), having a capacity of 
50 ce. 

(b) A water bath consisting of a vessel filled with sufficient water to per- 
mit of only a very gradual rise in temperature and equipped with a stirring 
device, preferably air blown. 

(c) An open tube manometer, made of glass tubing 6 mm. in diameter, 
filled with mercury to approximately 86 em., fitted with pressure tubing 
attached to a Y tube leading to the desiccator and the pump. 


Nore.—The difference in levels of the mercury in the manometer when the 
System is in operation, subtracted from the barometer reading taken at the 
same time, gives the vacuum of the system in millimeters of mercury. The 
Se between the barometer and the manometer reading should not exceed 

mm. 


(d@) A glass desiccator, having a hole at the side, constructed with heavy 
walls to withstand a vacuum of one atmosphere. 

(e) A laboratory water vacuum pump to expel the greater portion of air 
in the desiccator. 
(f) An oil. vacuum pump with motor to give a vacuum of not more than 
3 mm. 


Nore.—The Hyvac oil pump is satisfactory. This pump has a displacement 
of approximately 200 cu. in. per minute or 7 cu. ft. per hour at a speed of 900 


r.p.m. It will evacuate a flask of one-liter capacity to a vacuum of 1 mm. 
in two minutes. 


(9g) A weighing bottle with cork. The neck shall be small enough to fit 
inside the neck of the pykometer. This latter requirement is essential, since 
small quantities of pigment easily adhere to the ground-glass joint of the 
pykometer. 


(j) A thermometer having a range of from 0 to 60° C. graduated in 0.1° C. 


II. PROCEDURE 
2. The pykometer shall be filled with freshly boiled distilled water and 
brought to-a temperature of 15.5° C. It shall be dried and weighed as specified 
in Section 7. It shall then be cleaned, weighed, and dried. It shall then be 


[ia 


Specific Gravity Determinations 137 


filled with the kerosene to be used in making the test and again brought to a 
temperature of 15.5° C., and dried and weighed in the same manner as before. 
The specific gravity of the kerosene shall be calculated from the formula. 
/15.5° C. _ Weight of Kerosene 

Weight of Water 
3. The pigment shall be dried in an oven at 105° C. for 2 hours. 
Nore.—It is preferable to use an electric oven for this purpose. 


Specific Gravity 15.5 


Thermometer. 


Thin, long 
Capillary 
Tube 


Capillary 
Tube-->! 


(a) (b) 
FIGURE 48 


4. A sample of the pigment shall be weighed, by difference, in the weighing 
bottle. For blacks, blues, and lakes of light specific gravity, about 1 g. should 
be used ; for inert crystallin pigments, about 4 g.; for opaque white pigments, 
7 to 10 g.; and for red lead, from 15 to 20 g. should be used. 


Norre.—Due to the hygroscopic nature of some of the pigments it is neces- 
Sary to use a weighing bottle fitted with a cork stopper. 


5. Sufficient kerosene shall be poured into the pyknometer to form a 14-in. 
layer in the bottom and a quantity of pigment from the weighing bottle shall 
be added reaching approximately three-fourths of the distance to the kero- 
sene level. The kerosene shall always cover the pigment. The sample shall 
be stirred with a polished round-bottom glass rod until completely covered 
by the kerosene, more kerosene being added from the wash bottle if neces- 
sary. The rod shall be washed with kerosene. 

6. The pyknometers shall be placed in the desiccator, which shall then be 
closed and attached to the water pump until the greater part of the air is 
expelled from the system. This takes from 5 to 10 minutes. The system 
shall then be closed with a pinchcock and the desiccator attached to the oil 
pump for the removal of the small amounts of air given off at the low pres- 
sures obtainable with the oil pump. The manometer is used to indicate 
whether the oil pump is giving the proper vacuum. When the manometer 
indicates that the vacuum, which should not be greater than 3 mm., is con- 
stant, the oil pump may be cut off for short periods, precaution being taken 
that the vacuum does not change materially due to leakage. It will be noticed 
that bubbles of air come from the pigments very rapidly at first and that this 


138 Specific Gravity Determinations 


action gradually decreases and finally stops altogether. The time required 
for complete removal of air varies from 80 minutes to two hours, depending 
upon the nature of the pigment. When no more bubbles can be seen, it is 
assumed that all the occluded air has been given off and that the pigment 
is thoroughly wet with kerosene. Air can then be slowly admitted to the 
desiccator by means of the pinchcock. 

7. The pyknometer shall be taken from the desiccator and filled with 
kerosene, care being taken to add a suflicient quantity to prevent the forma- 
tion of air bubbles when placement of the thermometer is made. ‘The 
thermometer shall be placed in the water bath, which shall be cooled with ice 
to a temperature of between 10 and 13°C. The pyknometer shall be placed 
in the bath and be permitted to come to constant temperature. ‘The pykno- 
meter thermometer or capillary tube shall then be inserted. Enough warm 
water shall be added to the bath to raise the temperature suddenly to about 
14.5° C. in order to expand the kerosene and prevent it from creeping down 
the capillary and admitting a small amount of air. The bath shall be allowed 
to come to a temperature of 15.5° C. The capillary tube shall be wiped with 
filter paper and the cap put on. All temperatures on the thermometer in the 
bath shall be read, but not on the thermometer in the pyknometer. The 
pyknometer shall be removed from the bath and dried. It shall then be 
allowed to stand for 30 minutes to enable it to come to room temperature, 
and weighed. 

Notre.—It is advisable to allow the pyknometer to stand approximately the 
same time before each weighing so as to compensate for slight errors due to 
evaporation at the joints. 


8. The specific gravity shall be calculated from the formula : 


Specific Gravity of Pigments a 
(P+ K)—F 
In which K = Weight of the bottle filled with kerosene only ; 
P = Weight cof pigment used; 
fF = Final weight of the bottle with pigment and kerosene; 
S = Specific gravity of the kerosene used. 


9. Before a new desiccator is used for the first time, it shall be wrapped 
in a towel and tested under the vacuum to be used, great care being exer- 
cised in handling the desiccator when the vacuum is on, as any sudden jar” 
may cause it to collapse. 

10. It has been found convenient to run six samples at one time, the 
desiccator specified being of the proper size to accommodate this number. 


METHOD B: FOR TESTS REQUIRING HIGHEST ACCURACY. 


APPARATUS 
11. Apparatus—The apparatus shall consist of the following: 
(a) A pyknometer as shown in Fig. 48 (a) or (b) having a capacity of 
00 ce. ) 
(b) A water bath consisting of a vessel filled with sufficient water to Der 


mit of only a very gradual rise in temperature and equipped with a stirring 
device, preferably air-blown. 


Re eRe, i i i) ad 


Specific Gravity Determinations 139 


(c) A glass bell jar with a two-hole rubber stopper. Into one hole of the 
stopper is fitted a separatory funnel with a well-ground stop-cock ec, Fig. 49, and 
with the lower tube extending into the pyknometer (just below the opening of 
the side arm in Fig. 49 (a). Into the other hole of the stopper is fitted a glass 
tube with a well-ground 3-way stop-cock, Fig. 49, the tube connecting with the 
vacuum pump ¢, Fig. 50. The bell jar rests on a sheet of rubber, cemented or 
vuleanized to a glass or iron plate. With stop-cock ¢ closed and stop-cock d 
opened to the pump, the system shall withstand and maintain a vacuum. 


Norre.—A suitable desiccator may be substituted for the bell jar. 


= 
é . 


(d) A thermometer having a range of from 0 to 60° C. graduated in 0.1° C 
(e) A high vacuum pump e, Fig. 50. 

(f) An open-tube manometer f, Fig. 50, as described in Section 1 (c¢). 
(g) A storage bottle h, for kerosene or other wetting liquid. 


Stop - Cock 
d 


deparatory Funnel -----3 
Stop-Cock G --------- 


Bell Jar 


FIGURE 49 


PROCEDURE 


12. Procedure.—The pyknometer containing the weighed sample of dried 
pigment shall be placed under the bell jar. Close stop-cocks ¢ and d, start the 
vacuum pump and gradually open stop-cock d@ to the pump. When the air 
has all been removed, with a vacuum of 1 mm. maintained, fill the separatory 
funnel with kerosine, close stop-cock d, and at once gradually open stop-cock c, 
adding sufficient kerosene to completely cover the pigment. Stop the pump 
-and release suction at d. Finally fill the pyknometer with kerosine and com- 
plete the test as described in Sections 7 and 8. 


NOTES 


1. Before a new bell jar (or desiccator) is used for the first time, it shall be 
tested under a vacuum as described in Section 9. 

2. Stop-cock ¢ must be well-ground and should be lubricated with castor oil 
or glycerin. See precautions in Section 19 under Method C concerning the 
necessity of testing the system for leaks before making a determination. 

3. With certain pigments that are not wetted well with kerosine, the sub- 
stitution of turpentine has been found very efficient. However, when turpen- 
tine or any other liquid having a high evaporation rate, is used, a pyknometer 
of type a or b, Fig. 48, is not satisfactory. on account of losses around the 
ground-glass joints. When using such liquids as turpentine, the bottle (as a 


140 Specific Gravity Determinations 


pyknometer) and apparatus as described in Section 18 under Method C should 
be used, except that instead of attempting to measure an accurate volume of 
the liquid from the burette, the bottle (plus the sample plus the wetting liquid) 
is finally weighed as in Method B. 


FIGURE 50 


Apparatus Assembly for Determining Specific Gravity of Pigments, 


METHOD C: RAPID AND ACCURATE TESTING OF SINGLE SAMPLES 
APPARATUS 


13. Apparatus.—The apparatus shall consist of the following (see Fig. 50): 

(a) A 100-ce burette with a 75-cce. bulb in the upper part and the lower 
part (25 ce.) graduated in 0.05 ec. (see Fig. 51), 

(b) A special 100-ce. graduated flask, b, Fig. 50, with ground-glass stopper. 
The flask shall be thick enough to withstand and maintain a vacuum and 
Should weigh less than 35 g. The neck of the flask should be graduated in 
0.05 ce. between the 99 and 100-cc. marks. The dimensions of the flask are 
shown in Fig. 50. 

(c) A tightly-ground stop-cock c, in the burette a. 

(d) A 3-way stop-cock d, connecting with the vacuum pump e. 

( e) A high vacuum pump e, of the type requiring no preliminary or “back- 
ing” pump. 

Nore.—The “Hyvac” oil pump is satisfactory. 

(f) An open-tube manometer f, Fig. 50, as described in Section 1 (ce). 


Specific Gravity Determinations 141 


——a pee NY en 


Not 
less 
| than 


| 
x 


Burette: 


less 
than 
13 cm Jom. 


| Not 


Geissler, Straight. 

Glass Stopeock, 

Ground Accurately. 
Total Capacity, cc.... 100 
Capacity of Bulb, ec.. 0-75 
Graduated, cer. a7. 75-100 
Subdivisions, cc...... 1 /20 
Rate of Outflow, 

about 2 Min. 


~ 


1. .5.25cm 
if Opherica 


Not | 
less Ve. 
than 
Jom. 


| 


l..-NoF less than 60cm:--->| 


| 


Bae cep cicaremeseeeres) NOR iiore then 90cm. Por Win gion Tae wage | 


Tolerance: 


Total Capacity...0/10 ec. 
Graduate Portion .0.08 ce. 
Markings on Graduations 
should be in Conformity 
with the Bureau of Stand- 


| 


ey) ne ards Circular No. 9. 
SE 
35 Yi 
ra 
FIGurRE 51 


100-ce. Glass Burette. 


Norr.—The difference in levels of the mercury in the manometer when the 
system is in operation, subtracted from the barometer reading taken at the 
same time, gives the vacuum of the system in millimeters of mercury. The 
difference between the barometer and the manometer readings should not ex- 
ceed 1 mm. 


(g) A thermometer, g, having a range of from 0 to 60° C. graduated in 


1s een OF 
(h) A storage bottle h for kerosine or other wetting liquid. 


PROCEDURE 


14. Standardization of Apparatus.—The flask shall be connected to the 
burette and pump by means of a two-hole rubber stopper. The system shall 
be evacuated with stop-cock c closed until the pump maintains a vacuum of 
1 mm. in the flask (this requires only a few minutes). Close the 3-way stop- 
cock d for 30 seconds, and again open to the pump. There should be no appreci- 
able change in the mercury levels in the manometer, indicating that the system 
beyond stop-cock d is tight. With the vacuum still maintained, fill the burette 
from the top with kerosine, adjusting the level to the zero mark with a piece 
of capillary tubing. Now close stop-cock d and then carefully open stop-cock ¢, 
admitting about 75 cc. of kerosine into the flask. Open stop-cock d to the air, 
thus releasing the vacuum in the flask, and fill with kerosine to.a definite mark 
on the neck of the flask. Read the burette, calling this reading K (the volume 
of the flask). 


142 Specific Gravity Determinations 
ES 
15. Method.—The flask shall then be cleaned with ether, dried, and weighed. 
A glass counterpoise having the same superficial area and treated the same 
way may be placed on the opposite pan in the balance. A quantity of the dry 
pigment to be tested shall be transferred to the flask by means of a clean, dry, 
glass funnel whose stem reaches to the bottom of the bulb. A piece of stiff 
nickel wire is convenient in pushing the powder down the stem. The bulb of 
the flask should be nearly filled with the sample which, however, should occupy 
a volume of less than 25 ce. after all air is expelled. Greater accuracy may be 
obtained with a large sample than with a small one. The inside stem as well 
as the entire outside of the flask should be wiped with a clean piece of dry, 
lintless cloth. The flask and pigment shall then be weighed and the weight of 
pigment computed by deducting the weight of the empty flask. With the 
burette clean and dry, but with the stop-cocks well lubricated (castor oil or 
es the flask shall be attached to the evacuating system as shown in 
ig 50. After closing stop-cocks ¢ and d, the pump shall be started and stop- 
ie d carefully opened to the pump. Evacuation shall be continued until 
the pump maintains a vacuum of 1 mm. in the flask, or until all the air is ex- 
pelled from the system. The burette shall then be filled from the top as 
described in Section 14, stop-cock d closed, stop-cock ¢ gradually opened and 
kerosine added until the pigment is covered. The flask shall be tapped genetly 
to dislodge any air bubbles. The pump should be stopped, stop-cock d opened 
to the air, and the flask filled up to the same mark as was obtained in de- 
termining its volume. The volume of kerosine required may be designated X. 
Note the height of the liquid in the burette to the nearest estimated 0.01 cc. 


Norr.—The removal of all air can not be stressed too greatly, as the pres- 
ence of air will cause low results. 


16. Calculation.—The specific gravity shall be calculated from the formula: 


eS hety Gee em Water 
Specific Gravity of Pigment “For 
where 
S = weight of pigment used; 
K =volume of kerosine required to fill the flask when empty; 
= volume of kerosine required to fill the flask when the pigment is 


present. 


< 


17. Temperature.—Since the specific gravity of a pigment is only slightly 
affected by temperature, such variations as occur under normal conditions in 
a room would not materially affect the results. Care shall be taken, however, 
that the temperature of the liquid after transferring to the flask is approxi- 
mately the same as it was when in the burette. 

18. Wetting Mediwm.—While kerosine has been found to be a good wetting 
medium, any liquid which does not have a high evaporation rate may be used. 
The liquids are interchangeable, as no constants on them need be determined. 
Hence, a pigment containing a dye which is slightly soluble in kerosine could 
be run with another liquid in the same apparatus without special standardiza- 
tion for that liquid. Operators are cautioned against the use of water as it 
causes considerable frothing with certain pigments. 

19. (a) Precautions—Care shall be taken that the burette atop aces is 
well ground in order to prevent leakage of kerosine. Castor oil is suggested 
as the stop-cock lubricant. ' 


Specific Gravity Determinations 143 


(>) Since in determining both K and X, the tip of the burette and bore of 
the stop-cock plug are empty, no correction is needed; stop-cock c, however, 
should be so well ground that under a vacuum of 1 mm. for 30 minutes no leak- 
age of kerosine takes place. The usual sources of error are failure to remove 
all the air from the pigment and leaks in the system. The minimum amount of 
rubber tubing should be used anywhere in the system, and wherever this is. 
used the joints between rubber and glass should be coated with a melted mix- 
ture of beeswax and rosin. 

(c) In cleaning the flask of kerosine only, a rinsing two or three times with 
ether followed by dry air (dried over sulfuric acid and calcium chloride) is 
sufficient. When pigment is also present, both pigment and kerosine should 
be shaken together and then emptied. This should be followed with ether 
until no more pigment is removed. Some filter pulp (macerated filter paper ) 
and water (with or without some glass beads) should be added and shaken 
vigorously. Repetition may be necessary. The flask should then be rinsed 
with distilled water and either dried in an oven or rinsed with alcohol and 
ether followed by dry air. In determining specific gravity by this method, there 
is no reason why the flask if made of Pyrex glass can not be heated, followed 
by cooling during evacuation if such heating has no effect on the sample. 


Whirling Method.—Mr. Zieglemann* in connection with 
the determination of the specific gravity of pigments has re- 
cently utilized the centrifuge in place of the vacuum apparatus. 
A special brass cup 3 1/8 inches high and 1 1/4 inches dia- 
meter, volume about 50 ce. fitted with a one hole brass stopper 
is provided. The volume of the cup to the top of the hole in 
the stopper is determined. Then to the cup containing about 
29 ec. of wetting liquid, a suitable amount of pigment is 
added. After the pigment is entirely wetted the cup is placed 
in the centrifuge and whirled for about three minutes. The 
stopper is then put in place and liquid added from the burette 
until the vessel is filled. The calculations are the same as 


those of the A. S. T. M. method and the author claims good 
agreement. 


Specific Gravity of Mixed Pigment.—For calculating the 
specific gravity of a mixture of two pigments in definite pro- 
portions, when the specific gravities of each are known, use 
this formula: 


100 +( = a = )- specific gravity of mixture. 


Where P and P’ are the percentages of the two pigments and S and 
S’ are their respective specific gravities. 


* Paint, oil and Chemical Review Aug. 4, 1927. 


144 Specific Gravity Determinations 


Example: 
100 + (stig)- 
é 
100 
100 + (8.43 + 14.56) = 90 OG 


4.35 (specific gravity of mixture). 


Average Specific Gravity Data. For the convenience of 
manufacturers who do not have facilities for making specific — 
eravity determinations on various types of pigments, and who 
desire a chart showing the average specific gravity of many of 
the commonly used pigments, a special table has been pre- 
pared. It should be pointed out, however, that the specific 
gravity of even such colors as are termed chemically pure, 
such for instance as chrome green, may vary to a great extent. 
This is due to the fact that these greens may contain a small 
or a large percentage of blue, and in some instances varying 
amounts of lead sulphate. This variance in composition, 
therefore, of even chemically pure colors, 1s sufficient to warn 
the paint grinder that serious mistakes may occur in caleula- 
tions made on average specific gravity figures of certain col- 
ored pigments. <A chart is also presented showing the specific 
gravity and bulking values of many liquids that are used in 
paint and enamel manufacture. 


Weight One 
per Pound 
Specific Solid Bulks 
Gravity Gallon Gallons 
ALUMINUIn “Dusts ck eee 2.64 21.99 0.04548 
American Blue (Ferrocyanide Blue)+ 1.85 15.41 06489 
Antimony" OF10Gs), si. set eee 3.73 47.73 .0209 
Darytes s.r Cee oe Oe ae 4.45 37.07 .02698 
Basic Carbonate White Lead...... 6.81 06.73 « .01768 - 
Basic Sulphate White Lead...... 6.41 53.40 01873 
Brown Oxide (50% Fe,0,)........ 3.35 27.91, .03583 
SAN CY 2c we he eee | = 2,62 21.82 04583 
*Chrome Green: Os ey ane esd eee to. 
*Chrome Yellow, Os-by..6. nents ; *6.00 
Ohrominum (Oxide sioss- ee 4.95 41,23 02425 
BT DOn s BIS Gi ecu s, i ceten aden eee 1.81 15.08 .06631 
‘* Diatomaceous’ Marth .5..0 ss ceen 1358 


* These will vary widely according to composition required for shade or 
tone and character of base. 

+ Chinese, Milori or Prussian. 

**These will vary widely. 


Specific Gravity Determinations 145 


Weight One 

per Pound 

Specific Solid Bulks 

Gravity Fallon Gallons 

MMSTEME EG Foe at ofa cbs. eichs ct sale se ene 2.64 21.99 04548 

DIR TN ee) a cc Ses Sas 0 eas .8 0 oe 2.86 19.66 05086 

ES Wot 2 a REET 29 O1 04365 

Ferric Oxide (98% Fe,O,)........ 5.15 42.90 base L 

ieee mimeral Willer.............. raw PVE 04431 

PURIST ESOL ioe ore gas G6 + ces esas 2 ac Lyte: 14.83 06743 

Indian Ked (90% Fe,0,)........:. 4,92 40.98 02440 

IEE TLRS, Teor b0, ela g < woe'e o's 2.85 23.74 04212 

SSE iE S08 Sa a 11.09 92.38 .01082 

PPC TOOL -GTECD . , 6 ccc ccc ec ee woe 2.80 23.382 .04288 

(ONCE Se AS a a a 9.40 78.3¢ .01277 
Lithopone (50% ZnS) High 

NACE Gye S08 OEE ia 4.20 34.99 02858 
Lithopone (28% ZnS) Regular.... 4.30 35.82 02792 
RO Heit a ceo favwc a on « #0 00 4070 2.80 2o.08 04288 
REMC VITO icc cn po cate es pace os 8.80 To.0 01364 
Mineral Brown (45% Fe,0O,)...... 3.34 27.82 03595 
Para Red 10% (on Lime and Bari- 

MRNA SeR NRTA e Senn ooo nicl adn 9% ace 2.65 22.07 04531 
eee or ata PONG. 6 fe sek ce es 1.50 12.50 O800 
Pure Toluidine Red Toner........ 1.49 12.41 OSO058 
ON GIRS G0 ee 8.80 13.00 .01364 
Red Oxide (40% Fe,0,).......... 3.45 28.74 038479 
mensOxide. (959 We,O........6.. 4.95 41.23 02425 
MITE STIETO ce ee got o-e okies ces we 3.99 32.90 03040 
BEEN Po cc cies ce eles lke ee ear 27.24 038671 
Say ie Se 7 2.65 22.07 04531 
OR Is Oa i er 2.84 23.66 04227 
Titanium Oxide (100% TiO,)..... 3.94 32.82 03047 
Titanox (Barium Base).......... 4.30 35.82 02792 
Tiuanox (Calcium Base)......... 3.13 26.07 .03836- 
BRIM ees cletala kati edle < siesacs ss 3.95 32.90 .03040 
WT POAT Ee. SIG1UC 6 dies Sane es ce ss 2.85 19.58 05107 
USES oe Tap i a ~ 3.80 31.65 .03160 
MA irre eed <6 soc Se 2.68 Lap seed 04480 
*Venetian Red (20% Fe,O;)....... 3.05 25.41 03935 
ee ire ego's hee ss Apache ahirnage™ oan pg | ao 04431 
eA ST tM AS cry bias 6 o's oe se sss 7.06 58.81 .01700 
OPN SG 2: leg a er 5.66 47.15 02121 
Zane wxide, Leaded 35%.......... 5.95 49.56 02018 
PROMS ws a clcs os eee co ee owe ke 4.00 39.02 .03001 


Apparent Density of Pigments.—Some laboratories con- 
sider of importance a property which may be called ‘‘appar- 
ent density,’’ which is the mass of a certain volume of loose 
ary pigment. Although not standardized the following meth- 
ods of determination have been used at this laboratory: A 
eylinder (about 100 cc.) is used. The levelled off volume of 
the cylinder is determined. Enough of the pigment sample 
to fill the cylinder about three times is passed through a 10 
mesh sieve by gently stirring with a spatula. From 5 to 7 


*These will vary widely according to composition required for shade or 
tone and character of base. 


Specific Gravity Determinations 


146 


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Specific Gravity Determinations 147 


loads of the spatula or a small scoop are then used to fill the 
eylinder. The contents of the cylinder is then levelled off 
and the weight of added pigment determined. Precautions 
must be taken to avoid jarring the cylinder while filling it. 

Variations in the method are, (1) the use of a graduated 
eylinder in which case the actual volume of 6 spatula loads 
is noted; (2) filling as in (1), packing the pigment by drop- 
ping the cylinder 100 times from a height of 10 cm. onto a rub- 
ber stopper and then noting the volume and (3) sieving the 
pigment several times instead of once before filling the cylin- 
der. The following results on a series of lamp blacks illus- 
trate the methods: 

TABLE 30 


APPARENT DENSITY OF LAMP BLACKS. 
(Grams Pigment Occupied by 1000 cc.) 


Sample No. 1 No. 2 No. 3 No. 4 No. 5 
Method 1. 126 124 116 124 123 
Cylinder filled and leveled 128 122 124 Lass 128 
off. 129 125 123 126 129 
Mean (128) (124) (121) (124) (127) 

Method 2. 
6 loads (about 100 ce.) in 131 126: 124 126 128 
a 250 cc. glass cylinder. 134 128 120 126 isl 
Mean (133) (127) (122) (126) (130) 

Method 3. 


The contents of cylinder in 
Method 2 packed by drop- 
ping 100 times from a 


height of 10 cm. onto a 200 191 192 197 201 
rubber stopper. 206 198 193 194 203 
Mean (203) (195) (193) (196) (202) 

Method 4. 

Method No. 1 except that 122 119 116 120 121 
the pigment was sieved 125 120 118 118 124 
5 times instead of once. 126 118 120 118 128 

Mean (124) (119) (118) (119) (124) 


Method for Determining Specific Gravity of Paint Liquids. 
The specific gravity of a liquid may be determined with sufh- 
cient accuracy with a Westphal balance or a standardized hy- 
drometer and thermometer in the customary manner, making 
any necessary corrections for temperature. For viscous blown 
or bodied oils or for mixed paints, satisfactory results may be 
obtained, when a quantity is available by weighing a liter of 
the oil or paint in a graduated tared liter flask. When only 
small amounts are available or when great accuracy is desired 
the method below* should be used: 


*The above described method is adopted from the proposed tentative 
standard test for the specific gravity of road oils, road tars, asphalt cements, 
and soft tar pitches. See Proc. Amer. Soc. Test. Mater., Vol. XX, 1920. 


148 Specific Gravity Determinations 


The specific gravity of an oil is expressed as the ratio of the 
weight of a given volume at 25° C. to that of an equal volume 
of water at the same temperature. The determination of 
specific gravity, in the case of heavy bodied oils especially, is 


7 em we re ee we a ae 
me a ee ee ee 


FIGURE 52 


Pyknometer 
or weighing 
bottle. 


best made in a straight walled glass tube pyknometer approxi- 
mately 70 mm. long and 22 mm. in diameter, carefully ground 
to receive an accurately fitting glass stopper with a hole of 1.5 
to 1.7 mm. bore in place of the usual capillary opening. The 
stoppered tube should have a capacity of about 24 ec., and 
when empty should weigh not over 35 grams. 


The type of bottle described is illustrated. 


The pyknometer with stopper is first calibrated by weighing 
it, clean and dry, upon an analytical balance. This weight is 
called A. It is then filled with distilled water at a temperature 
of 25° C., the stopper firmly inserted, all surplus moisture 
wiped from the surface with a clean, dry cloth, and again 
weighed. This weight is called B. 


For the determination of the specific gravity of an ordinary 
oil or paint liquid, the material shall be brought to a tempera- 
ture of 25° C. and poured into the pyknometer until it is full, 
using care to prevent the inclusion of air bubbles. The stop- 
per is then inserted and the excess of liquid forced through the 
opening is carefully removed with a clean, dry cloth. The 
pyknometer and contents are then weighed, and this weight is 


“a 


Specific Gravity Determinations 149 


ealled C. The specific gravity of the material may then be ecal- 
eulated from the following formula. 

GAs 

B—A_ 


Specific gravity = 


When the specific gravity of extremely heavy bodied oils or 
blown oils, or certain paste products is to be determined, the 
viscosity of these materials may make the previously described 
method inapplicable. Such materials should first be gently 
warmed, using care to prevent loss by evaporation. When 
fluid, enough is poured into the clean, dry pyknometer to about 
half fill it. Precautions shall be taken to keep the material 
from touching the sides of the tube above the final level and 
to prevent the inclusion of air bubbles. It is advisable to 
shightly warm the tube before filing. The pyknometer and 
contents are then cooled to room temperature and weighed 
with the stopper. This weight is called C. The pyknometer is 
next removed from the balance, filled with distilled water, and 
the stopper firmly inserted. It is then completely immersed 
for not less than 30 minutes in a beaker of distilled water 
maintained at 25° C., after which it is removed and all surplus 
water wiped off with a clean cloth. It is immediately weighed. 
This weight is called D. The specific gravity of the material 
may be calculated from the following formula: 

A) 


Brouitt era ViLYos oe ce oe es a eS 
cope CRs Apne at) 


150 


Specific Gravity Determinations 


Leanne eee ee ees aacaacaacaacaaacaaaaacaaaaaaaal 
TABLE OF BULKING AVERAGES OF VARIOUS LIQUIDS 


Specific 

Gravity 
ACCTORO a Sul pas Sew Sale ese bon 
Amyl Acetate (85-88%) .........+- 0.8600 
Amy: Alconol 5305.05 5 Vs Dior otal ae .8266 
NRSOY Meals aes dae Pirie a nied eee 0.8019 
Aleohol (No. 1 Denatured)....... 836 
Benzine (62°) ii. So eee bee 745 
Benz. OR es hee ee a ee 883 
Butyl. Acetater cuss ae s paarncae 0.8763 
Bitty! Alcoholics ee ein 64 wie sce ees 8057 
Camphor ih. 0k oie se <a a ee le ee .963 
Carbon Tetrachloride. .«.......... 1.583 
Castor OF “CBIOWIN 60 eins oe .9942 
Cyclohexanoly.. 06 or nde ves on oie .9624 
Di Acetone Alcohol............... RS 4 
Diamyl Phthalate... voni ne ae 1.0252 
Di. Butyl Phthalate... ic 22. +s 3 oe 1.04 
Di: Butyl Tartrate. os n-ne eee 1.08 
Diethyl “Oxalate ges is cess van eee 1.0801 
Iiethy] Phthalate... 5 si. 5 os steele 1.1224 
Esterified Rosin (Ester Gum).... 1.08 
Ethyl Acetate (85-88%).......... 0.8883 
Ethyl Acetate (99-100%)......... 0.9001 
Ethyl Alcohols. seas cee ptetee .7850 
Ethyl Lactate, cic. cee eee 1.0384 
Purtarake 3 os0 we ie ee eee 1.16 
Frsel Oi; “Retined 3 .. aac Soa 0.8139 
Grain, \AlGOnOII <6 teste a uses .T85 
Hereasol: vous eeatietias so eke eee .893 
Hexol .R (Solid. Resin)... a eee 
isopropyl Aleouol..2 cacesew eee 78 
Lindol (Tricresyl Phosphate)..... 1.17 
Linseed Oil, Boleds ....402 4.000 «eee 4942 
Linseed Oil, Heavy Bodied........ : .98 
Linseed: Oil, Raw ws <s css 32 
+Liquid<Paint Drier. €)..55 2 85 
{Mineral - Spirits. ices «os eel eee T73 
{i.ixine Varnish... issn oaleoeeee .905 
Nitrocellulose, CDry ) <> .10see ee Sina 
*RESINS 4. hee ed oe ee 1.05 
Solvent Naptha (160*). 4. oe ae 902 
soya Bean Oil, Raw.%W.5.002e. 03 ou .929 
TORQ! | sais acaiats Sane Ole see eee S72 
Tung Oil, zRawWiiw ess sok eee .940 
Turpentine 74.5 .4)h4 9 28 ea eee ees 867 
Wood Alcohol (Methyl)......:... io 
32 0z. Solution L. V. Nitrocellulose 
In Butyl Acetate... wot ee 953 
UPCR Sk is Dae tae ee 1.323 
DUO Fs eo rs as ce re ae S76 


Weight One 
per Pound 
Solid Bulks 
Gallon Gallons 
6.639 1506 
Take 0.1396 
6.886 0.1452 
6.68 0.1499 
6.964 1486 
6.206 1611 
7.355 .1359 
7.30 OAS71 
6.711 0.1492 
8.022 0.1246 
18.190 0.0758 
8.247 pide 
8.017 0.1247 
7.664 1305 
8.54 OT17I 
8.663 1154 
8.996. 1112 
9.00 0.1112 
9.35 0.1070 
8.996 102 
7.40 0.1351 
7.90 0.1334 
6.538 0.1529 
8.65 0.1160 
9.663 0.1035 
6.78 0.1473 
6.539 .1529 
7.4389 1344 
11.08 .09025 
6.497 0.1539 
9.746 1026 
7.847 1274 
8.163 1225 © 
7.764 .1288 
6.681 1497 
6.456 1549 
7.539 1326 
ce 105 
8.747 .1148 
7.514 13381 
7.739 1292 
7.264 dole 
7.830 me lef Ws 
1 .Qae .1385 
6.589 .1518 
7.914 .1264 
11.02 0.0907 
527 0.1370 


+ These liquids will vary greatly in specific gravity. Grinders should ae- 


termine the figures for the products they use. 


Moreover, different batches of 


liquids given above may vary slightly in specific gravity. 
* Most Resins are of the approximate value given above. 


CHAPTER X 


DETERMINING COARSE PARTICLES IN PAINT PIGMENTS 


The method originally devised for this purpose by the 
writer and published in the earlier editions of this volume has 
recently been adopted with some slight changes by the Amert- 
ean Society for Testing Materials. It is presented below. 
This specification is then followed by data on special manip- 
ulative requirements worked out in this laboratory. 


A. 8S. T. M. STANDARD METHOD OF TEST FOR 
COARSE PARTICLES IN PAINT PIGMENTS 

1. The apparatus shall consist of a 3-in. No. 325 (44 micron) sieve conform- 
ing to the Standard Specifications for Sieves for Testing Purposes (Serial 
Designation: E 11) of the American Society for Testing Materials.* A 3-in. 
No. 325 (44 micron) sieve for comparison purposes should be retained in the 
laboratory as a standard. Whenever a new Sieve is secured, a practical test 
of its accuracy should be made by running on it and on the standard sieve a 
pigment that has a considerable percentage of coarse particles. A reserve 
stock of such pigment should be kept for this purpose. 


Il. PROCEDURE 


2. The sieve shall be weighed on an analytical balance, the weight being 
recorded in a figure carried to the third decimal place. The sieve shall then 
be wet on both sides with the liquid to be used for wash purposes. 

3. The sample of the pigment to be tested shall be weighed. For most pig- 
ments 10 g. will be the proper quantity. For black pigments of low specific 
gravity 2 g. will be sufficient. For pigments like Prussian blue and graphite, 
3 g. are generally used. The weighed samples of pigments shall then be trans- 
ferred to the sieve. 

If the pigment is one that is difficult to wet with the wash liquid, the 
quantity weighed out should first be placed in a beaker containing some of a 
liquid that easily wets the pigment and that is miscible with the wash liquid. 
For example, if water is to be used as the wash liquid, alcohol may be used 
as the wetting medium. The pigment is then gently stirred with the wetting 


* Sieves 3 in. in diameter will be received by the U. S. Bureau of Standards 
for test. The cloth will be tested to determine whether or not it conforms to 
the specifications for cloth of the U. S. Standard Sieve Series. The specifica- 
tions for the sieve frame are now being prepared. No. 325 (44 micron) cloth 
of the U. S. Standard Sieve Series should be made of wire 0.036 mm. (0.0014 
in.) in diameter, a tolerance of 15 per cent under and 35 per cent over being 
allowed on this diameter. The average opening between adjacent parallel 
wires should be 0.044 mm. (0.0017 in.), the tolerance being 8 per cent with 
the additional limitation that the maximum opening shall not exceed 0.044 mm, 
by more than 90 per cent. Sieves whose cloth conforms to these specifications: 
and whose frames are in accordance with specifications now in preparation 
will be marked with the letters ‘‘BS” and the year in which the test is made. 
A report will be issued for each sieve submitted, a nominal fee being charged 
for this test. 


152 Coarse Particles in Pigments 


liquid and the contents of the beaker transferred to the sieve. Where small 
particles of pigment are retained on the stirring rod or walls of the beaker 
they may easily be removed with the brush. 

4. The sieve shall then be held under a tap delivering about 300 to 500 ce. 
of wash liquid per minute. By slightly shaking the sieve, the pigment will be 
rapidly carried through. <A soft camel’s hair brush may be used in aiding 
the operation. If the sieve is held at a slight angle so that the pigment will 
gradually collect at one edge during the washing process, and then rotated, the 
pigment may be brushed out rapidly, with no risk of clogging the screen. 

5. After the majority of the finely divided portions of the pigment has 
passed through the sieve (from 2 minutes to 1 hour, according to Kind of pig- 
ment), the sieve shall be placed in an 8-in. porcelain dish containing 250 ce. of 
the wash liquid. The sieve will thus be covered to a depth of about ¥% in. 
The pigment remaining on the sieve shall be brushed with a soft 1-in. camel’s 
hair brush at the rate of two strokes per second during two periods of 10 
seconds each. The sieve shall then be raised from the dish after each 10- 
second period to let the liquid on the sieve run through. The liquid in the 
dish should be changed after every two brushing periods described above. 
This operation shall be continued until the wash liquid passing over the 
residue and through the sieve is clear and free from solid particles. 

NotEe.—When the operator thinks he has completed the washing he should 
catch about 200 ce. of the liquid in a clean 400-cc. beaker, stir vigorously and 
set the beaker on a black surface in the case of white pigments and a white 
surface in the case of colored pigments. The washing is not complete until 
a test as described above fails to show any particles collected about the middle 
of the bottom of the beaker. 

Occasionally pigments will be found that foam when water is used as the 
wash liquid. In such instances, during the last washing in the porcelain 
dish, the use of a liquid that breaks down the foaming and is readily miscible 
with water, such as alcohol, will usually overcome this difficulty. 

6. The pigment particles adhering to: the brush shall then be washed back 
onto the sieve and the water below the sieve wiped off. A few drops of 
alcohol and then of ether should be added to expedite drying. The screen 
shall be dried for one hour in an oven at 105° C., or on a radiator, cooled, 
weighed, and the percentage of coarse particles calculated. 

7. For pigments requiring wash liquids such as turpentine, mineral spirits. 
or kerosine, the wash liquid shall be siphoned from a vessel onto the sieve, 
finishing with ether to remove the wash liquid adhering to the sieve. 


Discussion of Method.—There are presented below some 
comments arrived at as the result of the examination of a 
large number of pigments at this laboratory. Illustrations 
of the method of running the test are also given. 

If the pigment is one that is difficult to wet with the wash 
liquid, the quantity weighed out should first be placed in a 
beaker containing some of a liquid that easily wets the pig- 
ment and that is miscible with the wash liquid. For instance, 
if water is to be used as the wash liquid, alcohol may be used 
as the wetting medium. The pigment is then gently stirred 


Coarse Particles in Pigments 153 


with the wetting liquid and the contents of the beaker trans- 
ferred to the screen. Where small particles of pigment are 
retained on the stirring rod or walls of the beaker they may 
easily be removed with the brush. 


For those who desire to investigate the subject further the following 
references are given: 

The classification of Fine Particles According to Size. By G. W. Thomp- 
son, Proc. A. 8. T. M., Vol. X, 601 (1910). 

Kolloid Zeitschrift. Vol. 18, page 3348, 1916. 

Rapid Test for Fineness of Paint Pigments. By Dr. C. D. Holley and J. 
C. Brier. Drugs, Oils and Paints, May 10, 1915. 

Comparative Tests for Fineness of Pigments. By Dr. C. D. Holley. Paint, 
Oil and Chem. Review, No. 23, 1921. 

Circular No. 90. By H. A. Gardner, Scien. Sec., Educat. Bur., Paint Mfrs. 
Assn. U. S. 

A Photomicrographic Method for the Determination of Particle Size of 
Paint and Rubber Pigments. By Henry Green, J. Franklin Inst., 192,637 
(1921). 

See also “Optical Properties of Pigments,’ H. E. Merwin. Proc. A. S. T. 
M., Part II, 1917, page 496. 


Occasionally pigments will be found that contain quantities 
of soft lumps or aggregates of finely divided particles which 
have been cemented together by moisture or by overheating 
during the drying process. All of these lumps will not pass 
through the screen even with brushing, as the brush is too 
soft to break down the aggregates. Placing these lumps be- 
tween the fingers and exerting slight pressure on them will 
readily indicate whether they are single coarse particles or 
ageregates of fine particles which may be broken down by 
slight pressure. In the latter instance, the lumps during the 
processing should be spread out in a glass petri dish and 
broken down with a spatula, using slight pressure but no 
grinding action. The contents may then be returned to the 
sereen with a wash bottle. In this way a great amount of 
time can be saved and accurate end points and readings ob- 
tained. 


It was found that certain pigments, such as white lead and 
lithopone, very often show a cementing together of particles 
that may be due to the presence of water-soluble metallic salts. 
Although continued soaking in water would ultimately break 
up such aggregates, it was thought that the use of water as a 
wash liquid would be inadvisable. This is due to the fact that 
oil is used for factory grinding and a similar liquid should 
be used for pigments having cemented particles, when running 
a sereen test. For such pigments, therefore, wash lquids 


154 Coarse Particles in Pigments 


FIGURE 53 
Determining Coarse Varticles with Water Method. 


Coarse Particles in Pigments 155 


consisting of mineral spirits, turpentine or kerosene have been 
recommended. Some may still prefer to use water, so results 
on both are given in the charts. 


(Ets 


FIGURE 54 


Using Mineral Spirits or Alcohol as a Wash Liquid. 


For pigments requiring wash liquids such as turpentine or mineral spirits, 
use apparatus shown above. This apparatus is also used for determining 
the fineness of paste paints ground in oil. For paints containing varnish, 
such for instance as Japan colors, a wash liquid of turpentine, solvent naptha 
or similar solvents is necessary depending on type of pigment. 


Again, with such pigments as Prussian blue a curious state 
of hard aggregate formation may be observed. While wash- 
ing with water would break up such aggregates (peptization 
sometimes occurring’), and in most instances show a residue 


Coarse Particles in Pigments 


156 


FIGURE 55 
200-Mesh Screen X-50 Unused. 


Standard 


PROM UORULBEER RU ULE TV EF 
S@hR@eageae: awe aae ee’. wpouwa BS 
eerrrrrerrr ey 
Seg huaue. aol acti blr fa 


FIGURE 56 


Standard 325-Mesh Screen X-50. 


Used 4 Times. 


Note Pigment Particles Retained. 


Coarse Particles in Pigments 157 


of less than 1 per cent, washing with kerosene or liquids in 
which these aggregates were not broken up would leave resi- 
dues as high as 62 per cent. 


In view of the widely varying results when solvents other 
than water are used, it is probable that no limit can be set 
for the percentage of residue from Prussian blue, when using’ 
liquids other than water. The use of mineral spirits will 
undoubtedly indicate to grinders what blues are best suited 
for rapid grinding in oil, but until color makers are able to 
wash and dry Prussian blue in such a manner as to prevent 
the formation of aggregates, it is probable that no standards 
within close limits can be set. 


Photomicrographs of Coarse Particles.—Six of the photo- 
micrographs of the coarse particles in pigments, shown in 
this chapter were made by a rather novel method discussed 
in one of the writer’s Articles on Fineness. By this method 
a very rapid examination of pigment particles can be made, 
especially if they are of coarse grain. Instead of requiring 
a long time for the preparation of special slides, special illumi- 
nation, ete., all that is required is a Victrola or similar talking 
machine record and a microscope. (See Figs. 57-62.) 

The test is made by rubbing with the finger a portion of the 
pigment across the grooves of a disc phonograph record and 
then observing the surface with a microscope. The Edison 
type of disc has a spiral groove with 150 convolutions per inch 
of radius. The lines are 1/150 of an inch from center to 
eenter. ‘The radius of curvature of the souud grooves is 
4/1000 (.004) of an inch. The average depth of the grooves 
is 1/1000 inch. - 

One record may be used for several pigments which may be 
numbered and the records kept in a cabinet for comparison as 
standards for various subsequent batches of pigments pro- 
duced or received in the factory. During the procedure of 
rubbing the pigments into the grooves, characteristic differ- 
ences are at once noted. Some pigments will feel coarse and 
gritty. Others will have a soapy or unctuous feeling. For 
instance, two samples of china clay or barytes which appear 
to be of equally fine texture when rubbed between the fingers, 
“may upon rubbing into the record show entirely different 
characteristics. One pigment may feel soft or ‘‘silky’’ in 
texture, while the other may feel granular and ‘‘gritty.’’ 


158 Coarse Particles in Pigments 


FIGURE 57 


Red Lead 
Some Particles Are Transparent. 


FIGURE 58 


White Lead. 


Coarse Particles in Pigments 159 


Pr tists ga 


FIGURE 59 


Barytes 


FIGURE 60 


China Clay. 
Note Transparent Particles. 


160 


Coarse Particles in Pigments 


NOOR ratte gal baths 


ay 


FIGURE 61 


Calcium Carbonate. 


FIGURE 62 


Bone Black 
Note Angular Hard Particles. 


ee 


Coarse Particles in Pigments 161 
ee 
Microscopic examination of the surface will then immediately 
disclose the reason for this phenomenon. 


Most pigments are made up of particles of varying size. 
The large particles are often covered with fine ones. When 
such pigments are placed on a record, the rubbing action 
forces the large crystals between the grooves and arranges 
them with their facets parallel to the face of the record. The 
fine particles are at the same time wiped from the larger 
erystals, so that the form of the latter is disclosed. With fume 
pigments, the very fine particles as well as the agglomerates 
may be shown. The relative degree of color, whiteness, and 
hiding power of the pigments are to some extent also tudi: 

beds 


For the microscopic examination it is advisable to use a 
32 mm. objective and a 12.5X eye-piece. Greater depth of 
focus is thus obtained and the magnification is sufficient. It is 
usual to look at the dise obliquely in order to get the specular 
reflection of the light. 


For a photographic record of the appearance of the pig- 
ments, great care should be taken that a strong light is pro- 
vided and that a water cell is interposed for absorbing the 
heat rays of the ight. Otherwise the light, impinging upon 
the record at one point, will cause a melting down of the 
grooves. Photography then becomes impracticable. 


Gallie-Porritt Apparatus for Coarse Particles—An arti- 
cle entitled ‘‘An Apparatus for the Separation of Grit and 
Coarse Particles from Fine Powders,’’ by G. Gallie and Por- 
ritt® describes a simple form of apparatus for this purpose. 
The principle of the method consists in suspending a pigment 
in water and supplying the mechanical force necessary to 
secure the passage of the fine particles through a sieve, at 
the same time breaking down any lumps present, by a jet of 
water under pressure. For detailed reference to this appa- 
ratus, the above publication may be consulted. 


Thompson Classifier for Paint Pigments.—An interesting 
apparatus for determining the coarse particles in paint pig- 
ments has been developed by G. W. Thompson of the National 
Lead Co., who described it in a paper entitled ‘‘The Classifi- 
cation of Fine Particles According to Size’’ in the Proceed- 


* J. Oil & Colour Chemists Assn., Sept., 1926. 


162 Coarse Particles in Pigments 


ings of the A. 8. T. M., Vol. X, 1910, from which the following 
information is taken. <A diagram of the apparatus is shown 
in Fig. 63. As will be noted from the illustration, it consists 


+o SEP 2 Beg 


[= (MRR o)! fi! a} 
ff 


Vi 
HY Att U 
, 
j 
y 


FIGURE 63 


Diagram of Thompson Classifier for determining the fineness of pigments. 


Coarse Particles in Pigments 163 


FIGURE 64 


Upper photograph is of portion No. 5 separated from red 
lead in Thompson Classifier. Lower photograph is of residue 
in Cone No. 2. Both photographs made at a magnification 
of 500. 


164 Coarse Particles in Pigments 


essentially of four or more cones (brass) of graduated sizes, 
placed one above the other, arranged so that the overflow from 
the top cone, passing through a funnel, discharges into the bot- 
tom of the second cone, and the overflow from the second cone 
passes through a funnel into the bottom of the third cone, and 
so on. The apparatus is arranged so that the liquid used can 
work at a constant head. Jerosene is usually used as the 
liquid. The material to be treated is diffused in kerosene so 
that the particles are completely separated and transferred 
into the first cone. A glass tube is then lowered into the 
cone until it nearly touches the apex. A current of kerosene 
under a constant. head is then caused to flow into the first 
cone through the tube. The smaller particles are carried into 
the next cone below, where the operation is repeated, and so 
on to the bottom, cone. The operation requires two hours, 
when the kerosene is allowed to settle and is decanted. The 
sediment in each case is washed into clock glasses with kero- 
sene, allowed to settle, decanted, and washed two or three 
times with ether. It is then dried and weighed. 


Fig. 64 shows the particles obtained in two different cones. 


a 


CHAPTER XI 


PARTICLE SIZE OF PAINT PIGMENTS 


While the author has referred on page 157 to a simple 
method he uses for the making of photomicrographs of pig- 
ments of relatively coarse particle size, the most approved 
method of making photomicrographs of finely divided pig- 
ments is that developed by Henry Green.* An abstract of 
Mr. Green’s method as prepared by him for this publication is 
given below: 


Green’s Method.—The fundamental idea involved in the 
method is by no means a new one. In all probability it has 
been employed many times by various investigators and for 
numerous purposes; yet the author is not aware of a single 
case where it has been sufficiently developed in detail so as 
to make it of practical importance in the special line of work 
to which it is here applied.+ 

Briefly stated, the pigment is prepared in such a manner 
so that a photomicrograph, at a known magnification, can be 
taken, showing clearly and distinctly the individual particles, 
which are then measured from the negative by a method to 
be described presently. | 


Preparation of Sample.—About a milligram of the pigment 
is placed on the center of a microscope slide to which is added 
a drop of redistilled turpentine. The slide is to be held at 
the two ends between the thumb and first finger; a glass rod, 
with smooth, straight sides, so that it will come in close contact 
with the glass, is now used to disperse and rub out into an 
extremely thin layer the material in the turpentine. This is 
best accomplished by a forward and backward motion of the 
rod in the direction of the length of the slide and extending 
over the central area only. The rubbing must cease at a 
certain critical stage, when there still remains sufficient 


*“A Photomicrographic Method for the Determination of Particle Size 
of Paint and Rubber Pigments,’ by Henry Green. J. Franklin Inst., 1921, 
p. 638. Also “The Microscopy of Paint and Rubber Pigments.” Research 
Bulletin, The New Jersey Zine Co., Palmerton, Pa. 

+The method of grain measurement exployed by metallographers is 
fundamentally similar to the photomicrographic method of particle meas- 
urement. Note on grain size, by G. H. Gulliver, J. Inst. of Met., 1918. 

“The Determination of Grain Size in Metals,’ by Zay Jefferies, A. H. 
Kline, and E. B. Zimmer, Trans. Am. Inst. Mining Engineers, 1917. 


166 Particle Size of Pigments 


PHOTOMICROGRAPHS AT 1285 DIAMETERS. 


American Process Zine Oxide Show- 
ing Characteristic Threelings. 


Basic Carbonate of Lead showing 
Basie Sulfate of Lead showing characteristic Hexagonal 


tendency to erystallize in cubes. Crystals. 


Particle Size of Pigments 167 


PereoviICROGRAPHS AT 1285 DIAMETERS. 


Gas Black. Barytes. 


so. 


Wits 
ui 
ay 


DS 

> 
. 

* 


Titanium Pigment. Silica. 


* This is only 650 diameters. 


168 Particle Size of Pigments 


turpentine unevaporated to prevent the mount becoming 
‘‘streaky,’’? and yet not enough to float the particles which 
would allow them to flocculate. By a slightly upward flour- 
ish of the rod on the last stroke the mount can be made wedge 
shape, that is, dense in one part and thin in another, with all 


PHOTOMICROGRAPHS AT 1285 DIAMETERS, 


Chrome Yellow showing character. 
istic Needles. 


Prussian Blue. Red Lead. 


intermediate grades of density between. In this way it be- 
comes possible to select a section for photographing that will 


Particle Size of Pigments 169 


show neither too many particles nor too few per given unit 
area.” 


Pe LOMICROGRAPHS AT 1285 DIAMETERS. 


Raw Sienna. Ochre. 


Antimouy Oxide. Zine Sulfide. 


* This method of dispersing the particles is to be used principally with the 
finest pigments, such as zine oxide, lithopone, white lead, etc. In the case 
of these materials it will be found impossible to produce any grinding effect 
that will cause the individual grains to be broken up into smaller ones. 
This is on account of the fact that neither the glass slide nor the rod are 
optically flat, and consequently they are unable to come in close contact with 
each other except at a very few points, 

With coarser materials such as clays, bartyes, asbestine, ete. (which will 
probably feel gritty), only the slightest possible pressure must be brought 
to bear upon them with the dispersing rod, for here there ‘is some danger 
of a real grinding effect becoming manifest. Fortunately, these materials 
are so large that flocculation does not prevent the outline of the particles 
from being seen and a measurement made, hence, very little rubbing is 
necessary. 


170 Particle Size of Pigments 


The next step, after the material is properly dispersed, is to 
completely remove the remaining turpentine. This should 
be done by laying the slide on a hot plate, the temperature 
of which is sufficiently high to cause evaporation within forty 
or fifty seconds. Care must be taken that volatilization is 
complete. This is satisfactorily ascertained by noticing if 
any odor of turpentine remains after heating. The particles 
will now be found to be cemented to the glass and should 
remain in this condition, if a reasonable amount of eare is 
exercised in handling the slide. When sufficiently cooled a 
small drop of glycerine is placed on the center of the mount 
and then covered with a thin slip. The exeess glycerine must 
be carefully squeezed out at the sides of the cover glass and 
absorbed by filter paper. The mount is finished in the usual 
manner with a ring of Brunswick black. 


If the above instructions have been properly carried out, 
and the mount now held to the light, the pigment, if its index 
of refraction is high, will just be perceptible as a faint cloud; 
if its refractive index is low, the pigment will be entirely in- 
visible, except with a microscope. 


Upon microscopic observation three essential conditions 
should be manifest. They are— 


1. The particles will be in one plane. 

2. They will be free from Brownian motion. 

3. ‘They will be dispersed, showing individual grains in- 
stead of aggregates and flocculates. 


Photography.—lIt is not the purpose of the present paper to 
describe the method of using a photomicrographie apparatus. 
It is also hardly necessary to add that unless one has acquired 
considerable facility in the manipulation of such apparatus 
it would not pay to attempt its application in the measure- 
ment of particle size. 


In regard to the present problem, however, it must be stated 
that all photographs are made with transmitted hight, and 
that this light is to be absolutely axial. Obliquity of illumi- 
nation will give a distorted image, causing an appreciable 
error in the results. 


The beginner will find it advantageous to start with a fine- 
grained contrast plate, using hydroquinone developer. After 
he has obtained experience in handling these materials suc- 


ae ee ee 


Particle Size of Pigments 171 


cessfully, he should then try his ability with panchromatic 
plates and develop with pyro. There are plates of this kin“ 
made especially for photomicroscopy which give great detail 
together with sufficient contrast. 


Magnification—Generally, in photomicrographie work, 
definition of structure is the one essential quality most de- 
sired. However, as the structure of a pigment particle will 
give us no information in regard to its size, the factor, defi- 
nition, may be neglected here to a certain limited extent.* 
On account of this fact it has been found an advantage to 
employ a magnification which otherwise would be too high 
if the best definition is to be obtained. Nevertheless, care 
must be taken that the photographic image of the particle 
gives edges sharply enough defined so as to make a satis- 
factory measurement possible. 


With a 2 mm. apochromatic objective a magnification of 
1,500 diameters will be most convenient for pigments such 
as zine oxide, lithopone, red oxide of iron, sublimed white 
lead, corroded white lead, Mathewson white lead, ete. Lower 
magnifications are used, naturally, with coarser materials. 


Measurement.—As previously pointed out, it sometimes 
becomes necessary to measure a thousand or more particles 
in order to obtain a sufficiently accurate average diameter. 
This demands a rapid method of measurement, if the work 
is not to become too irksome. The method is as follows: 
The negative, which must show from 200 to 250 distinct parti- 
cles, is placed in a stereopticon and an image of it thrown on 
a screen, so situated that the total magnification of the origi- 
nal particle will be from 20,000 to 25,000 diameters. The 
image of the particle is measured with a millimetre rule. 
Particles which are out of focus to any extent at all, as the 
case will be with those around the border of the negative, 
must be neglected. In order to eliminate the possibility of 
duplication and skipping, the area of the screen is divided 
into small squares. 

It is neither necessary nor desirable to consume time in 


estimating the fractional part of millimetres. These small 
errors are just as liable to be positive as negative, and it is 


* But to no greater extent than is shown in the photomicrographs. 


172 Particle Size of Pigments 
ee a a 
reasonable to believe that their sum approaches zero as the 
number of measurements increases. 

The length of time required for the measurement should be 
approximately two seconds. As the readings are called off 
an assistant takes them down. The results are plotted as 
particle diameter, d, against particle frequency, n.. This gives 
the so-called particle distribution curve. 

The particle of average size is a hypothetical particle that 
in some particular way represents the total mass of particles. 
Just what feature of the total mass of particles is to be repre- 
sented will depend upon the nature of the problem to be solved. 
One thing is apparent, however, and that is that one average 
particle size cannot serve for all possible purposes. The most 
useful average diameters expressed as functions of d and n 
are: | 


Arithmetical mean = Snd/Sn 
The diameter of the particle of average surface = VSnd?/Sn 


The diameter of the particle of average volume (the 
diameter determined with the slit ultramicro- 


scope) = ¥/3nd3/Sn 
The diameter from which specific surface is 
determined = Ynd3/rnd? 


SY 


Particle Size and Distribution by Sedimentation Method 
(Abstract)—A special balance pan is suspended in a pigment- 
vehicle mixture and the weight of pigment settling on the 
pan is noted at successive intervals of time. If the falling 
particles are spherical, the radius may be computed from 
Stoke’s law of falling particles. 


ee nh 
ro 2) (dessdaeniner 


where r = radius 
n= viscosity of medium 
h = distance in em. 
d'= sp. gr. of particles 
d* = sp. gr. of medium 
2 = gravity, cm/sec’. 


t = time, minutes. 


* J. H. Calbeck and H. R. Harnes, J. Ind. Eng. Chem. 19, 58—1927. 


Particle Size of Pigments eS 


— SS SS SSS SS 


Since pigment particles vary considerably in shape, the 
radii are those of a perfect sphere of the same material that 
sinks through the fluid at the same average rate as the par- 
ticle in question. Data on several samples of red lead and of 
one sample of litharge are presented in the original article. 

Relative Method for Determining Particle Size of Pig- 
ments.* (Abstract).—The authors measured the relative aver- 
age particle size of a pigment by determining the amount of 
hight transmitted by a suspension of the pigment. The amount 
of light transmitted by a suspension is inversely proportional 
to the amount of reflection from, the total surface of the pig- 
ment. Hence, the more finely divided the pigment, the greater 
the surface and the less the transmission. This relation holds 
true, however, only until the particle size becomes so small 
that it behaves as a source of light and scatters some of the 
light. This scattering out being directly proportional to the 
sixth power of the diameter of the particle, decreases rapidly 
with decrease in particle size. Hence, the transmission below 
the critical size increases rapidly and the hiding power of a 
pigment passes through a maximum as the particle size is de- 
creased. With this method a pigment must first be rated as 
to average size of particles by an independent method, but 
after such data is once obtained subsequent measurements 
of hiding power may be compared with that data. Since the 
refractive index of the pigment also is a factor in the opacit~ 
of a suspension, separate data must be obtained for each kind 
of pigment. 

Relation of Yield Value to Particle Size.+ (Abstract).—The 
pigment particles in a paint are visualized as groups of loose 
clusters of pigment particles easily dispersed by stirring and 
easily reformed as motion ceases. The flocculation is prob- 
ably due to interfacial tension. The force necessary to over- 
come this tension is probably the yield value. Since the 
interfacial tension depends upon the interfacial area (I. F. 
A.) of the particles and the number of points of contact (P. 
C.), the yield value involves these variables. Particle sizes 
of zine oxide were determined by photomicrographic methods. 
The yield values were measured by means of the Green and 
Haslam microplastometer. Determinations of yield value 
were made first by keeping the I. F. A. constant and varying 
the P. C.; and by keeping the P. C. constant and varying the 
I. F. A. The results are given in tables and charts in the 
original article. 


*G. F. A. Stutz and A. H. Pfund, J. Ind. Eng. Chem., 19, 51—1927. 
¥ Henry Green and G. S. Haslam, J. Ind. Eng. Chem., 19, 53—1927. 


CHAPTER XII 


SURFACE TENSION AND INTERFACIAL TENSION OF VARNISHES 
AND PAINT LIQUIDS 


While viscosity probably exerts a predominant influence on 
the working and spreading characteristics of a varnish or 
paint liquid, the appearance of the film after application will 
also depend to a certain extent upon the surface tension rela- 
tions existing between the liquid film and the solid underface. 
Phenomena such ag the tendency of oils to draw together in 
drops, the ease of wetting and grinding of various pigments 
with different oils, etc., have been conceived of as surface ten- 
sion effects. The pitting of varnishes and baking japans or 
paints may also be at least partly due to this cause. 

Surface tension as usually discussed refers to a tension or 
strain at the surface of a liquid in contact with air which 
causes the surface to act as though it were an elastic mem- 
brane. In a mass of liquid each molecule exerts an attractive 
force upon other molecules within a definite radius. As each 
molecule within the mass of the liquid is surrounded by other 
molecules, the attractive forces exerted upon it by surround- 
ing molecules is equal in all directions. The molecules im- 
mediately upon the surface, however, are exposed to mole- 
cular attraction only from the interior of the mass of liquid 
and there is consequently a molecular pull toward the interior 
of the liquid. The inward molecular pull results in a tendency 
to contract, drawing the surface molecules inward. 

While the measurement of this contractile tension at the air- 
liquid surface is of great theoretical interest and has numer- 
ous important applications (as, for example, the determina- 
tion of molecular weights, structure of compounds, arrange- 
ment of molecules in the mass, ete.) it has so far been of little 
assistance in solving the problems confronting the paint and 
varnish chemist. It does not serve to distinguish between 
liquids of the same class or to explain phenomena frequently 
observed. Difference in the density of the phases on opposite 
sides of the surface are so large as to obscure small differences 
in the tension of different liquids. Conditions existing at 
liquid-solid or liquid-liquid surfaces, are, however, of great 
importance in the present connection. At such a surface 


Surface Tension—Interfacial Tension 1B) 


where the density on each side is approximately the same, 
differences in the intensity of the tension of different hquids 
against another immiscible liquid or a solid may be detected, 
since here the combined effects of both liquids are measured. 
The tension existing at other than air-liquid surfaces is usu- 
ally distinguished as interfacial tension and will be go desig- 
nated in this chapter 


In varnishes (colloidal solutions) and paints (suspensions) 
where the surfaces between solid and liquid are extraordi- 
narily great, the magnitude of the interfacial tension between 


the phases becomes a very important factor in determining 
the characteristic of the liquid. 


There are, therefore, several kinds of surfaces to consider 
and it is desirable to ascertain whether there is any relation 
existing between the tensions at these surfaces in different 
liquids, and the characteristics of the hquid film. From a 
practical point of view, the most important of these various 
tensions is that at a liquid-solid surface. Very little is known 
concerning this tension, and it appears at present impossible 
to measure it. Relative values for the interfacial tension be- 
tween immiscible liquids can be easily obtained. The abso- 
lute methods of precision which are at present available, how- 
ever, apply to only one of the tensions—namely, that in the 
surface of the liquid against air, or its own vapor. 


Air-Liquid Tension.—Three methods are commonly used for 
measuring the contractile tendency existing at the surface 
of a liquid in contact with air. 


Capillary Tube Method—Surface tension is measured by 
the height to which the liquid will rise in a capillary tube of 
known diameter. The liquid rises until the tendency of the 
film to contract is balanced by the weight of the column of 
liquid. 

Drop Weight Method.—Surface tension is measured by the 
weight of a drop forming at an orifice of known diameter. The 
weight of the drop increases until it overcomes the surface ten- 
sion of the liquid. 


Air Bubble Method. Surface tension is measured by the 
size of an air bubble forced through the liquid, the size being 
proportional to the surface tension of the liquid. 


176 Surface Tension—Intertacial Tension 


These methods yield accurate results but require consider- 
able time and manipulative skill. The apparatus illustrated 
and described: herein is easily and quickly operated and yields 
results that check fairly close with the above methods. It was 
used for obtaining the figures given in Table 31. 

As indicated in Table 31, surface tensions of liquids of dif- 
ferent types, such as oils and volatile thinners, vary somewhat, 
but in different liquids of the same type the difference is too 
~ small to explain great differences in behavior. It also appears 
that liquids of different types may show the same surface ten- 
sion when they would be expected to have widely varying 
values. The measurement of surface tension, is, therefore, of 


FIGURE 65 


This apparatus, designed by Dr. P. L. DuNouy of the Rockefeller Medical 
Institute, is manufactured by Central Scientific Company, Chicago, Ill. For 
a description of the instrument and details of operation see Bulletin No. 82, 
Central Scientific Company, and the Journal of General Physiology, May 20, 
1910, Vol. 1, No. 5. 


ae a 


Surface Tension—Interfacial Tension es, 


little assistance in studying the physical peculiarities and 
variations in properties so frequently encountered in paints 
and oils. 


TABLE 31.—Measurement of Surface Tension Against Air by DuNouy 


Apparatus. 
Oils— Dynes per cm, 
ng vial eoiin macaw acdue 6 ¥ 6 See elas Genel elena's 38.5 
emermeiie yo a(. FOLY 10 MiNS: ...s. sina cs wee et ee ee eae 38.5 
ee ee TOY 2) WINS <. . . sv k oe sce wd ew ea ciceevas oo 
Serie eet POT S30) TAINS kok ce Sc ce wv eae c eae 38.5 
rrr maa roe TOT GO MINS. oc etee «oo ste ece cnccees 39.0 
eee Ome 4 = TOP Or IMINS ss osc cu ccs ee ee ele te eee 39.0 
EU BED 2 ae a ee a oid 
I iy sg vlads anda bmpuveenteiebuea vee 39.0 
Thinners— 
Ee Shaka sh cee «ke bet «pine csc pleas copeues 31.5 
MRTPEEILCTILOIUCTIZOL (6)... o 05.5 ce te ee st ees A a eer Me 40.5 
Mineral Spirits— 
<8 RRS oa ae Oy ese ER Sie RS Era ae a ag eR 29.0 
a oiay sds Se aad acd shes b ele sic s et yee cee ep aie 29.0 
ee 5 alg gslcice 55 Mie aS le oye 0, sles wid eco m cele ‘enn 29.5 
ERB ayaa cao wk sin ve s ociw sis ae sols cle wes es owe 29.5 
ee fae e lola k chdn o «bee @ew'aw eh ap ae wees 30.0 
a e Sra sb a sh's i's owe wietels s 90.5. ¥ aus ee oe 0 tlee 30.5 
so LS cl a's ss: abso pe wiets.e% vba cd ae ee ee eee 31.0 
a EE a ics cc ok wie ee ase 6 oe # ale gs be mela Sean Slee 


Since no way of measuring the tension at a liquid-solid sur- 
face is known, it is desirable that means be found for deter- 
mining values which will explain differences observed in 
different liquids. 


Wells and Southcombe* have observed a definite relation 
between the interfacial (oil-water) tension of lubricating oils 
and their power to wet metallic surfaces. They find that the 
lower this constant is, the greater will be the wetting power or 
‘‘oiliness’’ of the oil. The ability of various oils to wet a given 
pigment is probably governed by the same relation. If the ten- 
sion is low the oil should spread easily and be readily made to 
cover every facet of the pigment particles. 


Interfacial Tension.—Relative values for the interfacial ten- 
sion between liquids were obtained by the use of the apparatus 
shown at B in Fig 66. This apparatus as prepared by the 
writer consists of a 5 ec. pipette bent upward at the lower end 
and drawn to a point having an orifice of about .8 mm. It is 
supplied with a rubber tube and clamp to facilitate filling and 
to regulate the influx of air during the determination. The 


* Soc. Chem. Ind., pp. 51-60 T. (1920). 


178 Surface Tension—Interfacial Tension 


volume between upper and lower marks equal about 4 ce. The 
figures given in Table 32 were obtained with this instrument: 
The pipette is filled to the mark and maintained at this level 
by closing the clamp. The lower end is immersed in a beaker 
containing water or some other immiscible liquid at the de- 
sired temperature. Enough air is admitted by loosening the 
clamp to cause a slow efflux of oil in a series of distinet drops 
from the capillary tip. As the drops break loose and rise to 
the surface one at a time they are counted. From 5 to 10 
minutes are required for a determination. 


FIGURE 66 


The instrument shown at A has been designed by the writers 
to secure greater convenience in operation and greater ac- 
curacy, and will be used in future work. The size of the capil- 
lary to be used will depend upon the viscosity of the liquids 
tested. It may be advisable to have two instruments fitted 


ai 


Surface Tension—Interfacial Tension 179 
DTT ee 
with differ ent-sized capillaries to take care of extremes of 
viscosity.” 

If a capillary tube as shown at A is used it is eects that, 
in each determination the top of the tube be perfectly clean 
and free from the liquid the interfacial tension of which is to 
be measured. If it is not kept clean the liquid in emerging will 
spread over the top of the tube, producing drops of non-uni- 
form size and render the determination worthless. 


The number of drops formed by a definite volume of liquid 1s 
inversely proportional to the interfacial tension. In compar- 
ing two liquids specific gravity must be taken into considera- 
tion. The number is also influenced by both temperature and 
the depth of immersion of the capillary tip. Since observa- 
tions are made at or near room temperature, it will be suffi- 
cient to maintain the water at the desired point, as the liquid 
in passing through the submerged part of the tube to the capil- 
lary tip will come to the temperature of the water. If the 
beaker is always filled to the same height and the instrument 
rests on the bottom the degree of immersion will, of course, be 
the same. While the results thus obtained are only relative, 
the values for different liquids of the same class vary greatly 
and the differences are such as might be expected from their 
properties. 


In Table 32 a difference in drying oils and thinning liquids 
not shown by the usual surface tension methods is indicated. 
For instance, perilla and chia oils are seen to have a much 
higher interfacial tension against water than has linseed oil. 
If the same relation holds at solid-liquid surfaces (which ex- 
ists in applying the oil to a solid surface) it appears that this 
higher interfacial tension would account for the ‘‘crawling’’ 
of these oils. The low value found for extracted linseed indi- 
eates that the interfacial tension was reduced by the large 
percentage of free acid. Accordingly it was found that when 
different percentages of linseed oil acids were added to a lin- 
seed oil of low acid value, the interfacial tension was greatly 
decreased. 


The addition of linseed oil to perilla oil lowers the inter- 
facial tension of the latter against water. In the mixture of 


* This Laboratory has turned its design over to the A. H. Thomas Com- 
pany of Philadelphia. This firm has satisfactorily produced the apparatus 
In accordance with the design for $6.80. 


180 Surface Tension—I nterfacial Tension 


oils given the crawling effect was found to be entirely over- 
come. While heating for a few minutes at a high temperature 
appears to lower the interfacial tension, if the heat is con- 
tinued longer the tension again increases. The increase in 
viscosity, due to prolonged heating, apparently overcomes the 
surface tension effects in the case of perilla oil. 


TABLE 32—Measurement of the Tension at the Liquid-Liquid Surface 
Against Water 
All Measurements made at 20° C. 


Number 
Liquids of drops 
Raw Linseed 2.00004. eee ses eeuscus euls oes spelen 55 
Linseed extract (acid value 22) ...........). 00 ee 82 
95% Linseed 70 
5% Linseed acids CoC CCC ORO eee eee Ome e RO oe eb 6 6 0s 66 ols hie os) Sate 
90% Linseed dss ssesuscese ear 90 
10% Linseed acids { . 
80% Linseed 295 
20% Linseed acids eoeeetmweoeeseoe veep eBeoeeseee ss © 0 ¢ 06 2 6 8 6 6 6 8 8 8e 2 ee 
Perilla wc ccc ccs eeccevesaveuaneusnveasea eed shel neta = =a 37 
Chia. . cee ienetas Ga eueueeec ceases a anh eine e naz 32 
Perilla (heated at 280° GC. for 10 minutes). ... <u .eeeee 42 
Perilla heated 20 minutes at 230° C.......... «sie elenaieia ee 33 
Perilla (heated at 260° for 2 hours) .......... os eee 30 
Alkali ‘refined. Linseed “oil, cca. 2.2 ee POOR ee ee 44 
Acid refined Linseed oil... ........000+«s c+ we pe get 44 
Linseed fatty acids... 22. 5.05. 0.00 ca vo «ole ene eee ene 300 
66 2-3% Linseed 52 
3813% Perilla (°7771 ttt terete rest eet nneees se seueueae 
Varnish makers’ Linseed oil heated at 500° for 2 hours.............. 36 
Perilla heated to 300° C. rapidly.....2..,..0..s0ee eee 35 
Cold pressed Lumbang... 3.000. cc0s 5 «ee «ok ee pi eee 41 
AA oil (causes pitting of japans)..... ‘ele alle oe sine 5 gle a eta atten 33 
Varnish 2. ees c ccc ndw ey women ww a ecne sila ao ea 40 
Turpentine ...... 5 cee ees csecee nw oe cle oe 5 area ae nt nae 115 
Mineral spirits... .....0<600000 01+ us og ule ogee 79 
Against Salt Solution 
TUIpentine 22.660 cece de ecw ee neces soe se 5 0\ 8 alee nthe 135 
Mineral spirits. ...06...c00 0. bcos eeu eels s'est ce alten 89 


Turpentine and mineral spirits which show the same surface 
tension exhibit a very different interfacial tension against 
water. This result indicates that the selection of suitable thin- 
ners for various types of paint and varnish liquids is a matter 
of great importance. 


All solid surfaces are believed to hold an adsorbed film of 
moisture. Although this film may only be of molecular thick- 


ness, it may yet form a continuous layer between the solid sur- 
face and the applied coat. If such is the case it is conceivable 
that the surface is really liquid-liquid instead of liquid-solid, 
and that the conditions obtaining in the measurement of the 


Surface Tension—Interfacial Tension 181 


interfacial tension against water as described herein closely 
approximate actual working conditions. If this tension is in 
any way related or proportional to the tension which actually 
exists at a solid-liquid surface it should hold for all immiscible 
liquids. If a definite relation holds for the liquid to be tested 
against any immiscible liquid it could more justifiably be used 
as indicating solid-liquid tensions. When determinations 
were made using salt solutions the ratio between the number 
of drops of turpentine to mineral spirits was approximately 
the same as when pure water was used. 


An explanation for the existence of equal surface tensions in 
liquids of the same kind is advanced by I. Langmuir, who re- 
fers it to the arrangement of molecules in the surface layer. 
He states that: 


The group molecules of organic liquids arrange them- 
selves in such a way that their active portions are 
drawn inward, leaving the least active portions to form 
the surface layer, the active portion of the molecule be- 
ing that part of the field characterized by a strong stray 
field (residual valence). Surface energy is thus a meas- 
ure of the stray field which extends out from the sur- 
face layer of atoms. The molecules in the surface layer 
arrange themselves so that this stray field is a mini- © 
mum. 

The surface energy of a liquid is thus not a property 
of the group molecules, but depends only on the least 
active portions of the molecules and on the manner in 
which they are able to arrange themselves in the sur- 
face layer. In liquid hydrocarbons of the paraffin 
series, the molecules arrange themselves so that the 
methyl groups (CHs) at the ends of the hydrocarbon 
chains form the surface layer. The surface layer is 
thus the same, no matter how long the hydrocarbon 
chain may be. As a matter of fact all these many 
different substances from hexane to molten paraffin 
have substantially the same surface energy, namely 
46 to 48 ergs per square centimeter, although the mole- 
cular weights differ greatly. 

If now we consider the alcohols such as CH;OH, 
C2H,OH, ete., we find that their surface energies are 
practically identical with those of the hydrocarbons. 
The reason for this is that the surface layer in both 
cases consists of CH; groups. 


182 Surface Tension—Interfacial Tension 
eet 
Accepting the above statement as true, the measurement of 
the surface tension of liquids against air would yield im- 
portant information in regard to substances of different molec- 
ular groupings. It will not, however, serve to differentiate 
in any way between liquids which have the same atoms or 
groups in the surface layer. While it is possible that the so- 
called active portions of molecules may be drawn inward at 
any surface, whether air-liquid, liquid-liquid, or liquid-solid, 
it is probable as already pointed out, that the tension in the 
latter cases has a very different value from the former. Differ- 
ent vegetable oils may therefore show the same tension against 
air due to the fact that they all present the same group or por- 
tion of the molecule at the air surface, but it is conceivable that 
in contact with another liquid or a solid (pigment) different 
oils may have different groups in the surface layers, particu- 
larly if the active groups possess an affinity for the surfaces 
with which they are in contact. We have, therefore, different 
manifestations of the same force depending upon whether we 
are considering the tension between the liquid surface and air 
or the tension between the hauid and another liquid or a solid. 


Technical Paper No. 540 of the U. S. Bureau of Standards contains 110 
references on the subject of Surface Tension. 


CHAPTER XIII. 


ULTRAVIOLET LIGHT STUDIES ON PAINT PIGMENTS AND 
LIQUIDS 


Considerable work has been done by P. R. Croll and J. D. 
Jenkins, on the relative transparent nature of films to utlra- 
violet rays. The writer submitted to them early in 1924 a 
sample of a special glass that had been ground to a pigment, 
with the request that determination be made of its opaqueness 
to ultraviolet rays. Their photographs were made through a 
thin layer of metallic silver which is transparent only in a 
narrow band of the ultraviolet, around 3100A’s. Subsequently 
they received a Corning filter quite opaque to visible rays but 
very transparent to the ultraviolet down to about 3000 A’s. 


Fy 
Hy 
a 
H 
nititinnesstananaptonie 
povecevnnnon em eee Mee 


H 
| 
i 


FIGURE 67 


Diagram showing method of photographing pigments by reflected ultra- 
violet light. (Croll.) 


In their subsequent work on the glass pigment forwarded to 
them, they used as a light source an iron are with 5 amperes 
and 40 volts. Exposure was made in back of a screen, at a 


184 Ultraviolet Light Studies 


distance of about fifteen inches from the are, the screen being 
interposed between the are and the paper. The pigments 
were illuminated by the light from the iron are, the light pass- 
ing through the screen. They were then photographed by 
means of a pin-hole camera from above. A sketch of the ap- 
paratus used, together with the results obtained with zine 
oxide, the special powdered glass, silica, and white lead, are 
shown below. As was expected, the zine oxide appeared black 
in ultraviolet light, because such light is absorbed by this pig- 
ment. The pigments that did not absorb the ultraviolet light 
appeared white. 


FIGURE 68 
Photographs of pigments taken by reflected ultraviolet light. (Croll.) 
Transparency of Pigments to Ultraviolet Radiation.—Inter- 

esting work has been done on this subject by A. H. Pfund and 
Rk. L. Hallett. The most recent work, however, and probably 
the most elaborate was presented by G. F. A. Stutz in an 


article entitled ‘‘The Testing of Paint Pigments for Trans- 
parency to Ultra-Violet Radiation,’’ published in the Journal 


ie met oy 


Ultraviolet Light Studies 185 


of the Franklin Institute, July, 1926. <A description of the 
apparatus and method, as well as some of the results are re- 
printed below. 


H. A. Nelson, Proc. Am. Soc. Test. Mat., 22, Part II, p. 485 (1922). 
A. H. Pfund, Proc. Am. Soc. Test. Mat., 23. Part II, p. 369 (1923). 
G. F. A. Stutz, Jour. Frank. Inst., July, 1925, p. 87. 

R. L. Hallett, Proc. Am. Soc. Test. Mat., 23, Part II, p. 379 (19238). 


Stutz Apparatus and Method.—‘‘In this work, the apparatus 
has been modified as suggested by Doctor Pfund, so that both 
the reflected and the transmitted light are caught in diffusely 


Fhotograplic 
ws Prare 


/ Quarrz 
l Spectrograph, 
a 


/lntegrating Sphere for 
wreflected Light. 


Integrating Sphere 
lfercury Vapor Lamp. 


for Transmitted 
Light 


Fro tating 
Secror. 


FIGURE 69 


reflecting spheres. The arrangement is shown in Fig. 69. Light 
from the quartz-mercury lamp is rendered parallel by the 


186 Ultraviolet Light Studies 
(nh 
quartz lens L, and impignes on the paint film contained in the 
quartz cell. The total transmitted light is caught by the mag- 
nesium-oxide-coated sphere and enters the quartz spectrograph 
as shown. The light reflected by the film is collected in a simi- 
lar sphere. The whole apparatus is mounted on a slide, so that 
it ean be moved to the left until the light from the second 
sphere enters the spectrograph. 

‘(The amount of light reflected and transmitted in each case 
was measured by the darkening produced on the photographic 
plate. The rotating sector was used to give a series of com- 
parison spectra of known amount, transmission being made 
through a cell containing the clear vehicle, and reflection be- 
ing made from a surface of magnesium carbonate. 


‘“The cell used consisted of two quartz plates with a bronze 
separator, .09 mm. thick. The pigments were incorporated in 
castor oil, since this has practically no absorption in the wave- 
length interval from 4400 to 2900 AU. The spectrum in each 
ease is that of the light of the quartz-mercury are after pass- 
ing through a vehicle film .09 mm. thick. For more complete 


data on the absorption of ultra-violet light by vehicles the 


reader is referred to a previous paper. 

‘A weight of pigment equal to .053 ¢.c. (calculated from the 
density) was incorporated in 5 ¢.c. of castor oil. This is an 
approximate volume ratio of 1 per cent pigment, 99 per cent 
vehicle. When this mixture was placed in a cell .09 mm. thick, 
the amount of pigment in the cell was sufficient to form a layer 
00092 mm. thick. The thickness of the pigment layer was 
varied in some cases by the addition of a greater or less vol- 
ume of pigment. 


Results—‘‘Since the reflection factors parallel those of 
Pfund and the writer, the transmission measurements only will 
be presented. 


Table 33 gives the results for the white pigments, inerts 
and blacks, and Table 34, the results for the colors. The last 
column in each table gives the thickness at which the pigment 
is opaque to light of 3655 A.U.”’ 

Ultraviolet Effects Upon Paint Liquids.—The apparatus and 
method developed by Stutz for determining the effect of ultra- 
violet ight upon paint vehicles and originally presented in 
the December, 1926, issue of Industrial and Engineering Chem- 


Ultraviolet Light Studies 187 


TABLE 33 
White Pigment—Inerts—Blacks 


Per Cent. Transmission of Pigment | Thickness 


.00092 mm. Thick at at Which 
Pigment Wave-length Pigment 
Is Opaque 
to 3655 
4358 | 4047 | 3655 | 3342 | 3131 | 3023 | 1 mm. 
Antimony oxide pigment.................. 48 | 47 -| 39 | 24 10 0 .0065 
Hacic lead carbonate.......................... O0tmer 00s fOr 7.0.) o0e. 1 oF .0270 
Basic lead sulphate........................00. [ime COsee Oe tao boo tos .0052 
OS a ee SOm desea dea ryt oe 15 5 .0100 
Extra-strength lithopone.................. ya a ee a 20 f 8 .0085 


Pigment composite (40 per cent. 
lithopone, 40 per cent. zinc oxide, 


OO A Cad SOs 43°54 12 7 6 6 .0020 
PPGer Pte PMEIMENE) oo. 2.. <2. .ses. eee. ese O39 18 iS 12 11.5} ..0046 
100 per cent. titanium dioxide..........) 35 32 18 6 co: ha .0031 
Zinc oxide (American process).......... 44 | 38 0 0 0 0 .0009 
Zinc oxide (French process).............. 46 | 40 0 0 0 0 .0009 
Zinc oxide (35 per cent. leaded)...... 50 | 45 9 8.5] 8 8 .0015 
0S Te Se Serie 2h 1S 0 0 .0062 
LL a 90° 1-90 )<90 «1789 | 88 si and pea Cees? 
i ee as 68. |) 67 65 64,5647 4) 05/51 aie 
oA G39)-61 BOS st 5 Sir) OAS Ee ae 
Gloss white (BaSO, + Al (OH);)..... 79 | 80.5/ 79.5| 78 | 76 | 75 |... 
(Eo ad a a BP reGse Cae O82 “1h esc 7 Onin oe 
ccc. oenccyiseennnsccevnesseecennss- 88 88 85 82 80 (ita Mtoe a 
Ce ik SC Se 74.5| 76 (6 rece ied ie) 78 POl5 eee ae ce 
Rg, cay asses cceacsessepdeereseeess 71 69 68 67 66 OS lie Seat 
a er 0 0 0 0 0 .0006 
ee ee HG ced Pala Be 17 15 13 1h .0030 
ee .......| 26 | 24,5| 23 | 205) 19 | 18 | ........ 
yee.) 1.5) 1 eine aed i 1 .0015 
DRAG ic, (onncecaeveencs-ceeeoeecessssee 7 7 2G. eo 6 
Magnetic iron oxide (98 per cent.)....| 12 13 14 14 15 15 .0017 


istry, have been used to advantage in such studies. <A brief 
abstract of this method is given below: 


Method.—The effect of ultraviolet light on a mass of wet 
oil has been studied by placing about 300 ec. of oil in a 400-ce. 
flask of clear fused quartz, and exposing it to a Cooper-Hewitt 
quartz Uviare at a distance of 30 em. (12 inches). The oil was 
stirred continuously with a small glass stirrer, and a slow 
stream of air, oxygen, or nitrogen bubbled into the oil. The 
temperature stayed nearly constant, at about 50° C. The oil 
was sampled at intervals until it had attained a considerable 
body. The viscosity of the several samples was determined 
by use of the Gardner-Holt tubes and, in the case of the 
samples beyond the range of the tubes, the result was obtained 


188 Ultraviolet Light Studies 


TABLE 34 


Colored Pigments 


Per cent. Transmission of Pigment | Thickness 
.00092 mm. Thick 


Pigment 

4358 | 4047 | 3655 
Adwumantiny vst ee oe ee 47 46 45 
Bivetoer Ay, it wee es eee 50 47 22 
Chinese Dives. je) 00 ieee arte eee ee 48 39 28 
Iron lite. Ssh. cao a ete ee 70 63 57 
Ponsol bine ee a ee ee 75 53 49 
Prussian bide hey aan eee 58 36 31 
RIVISTA DINE. O eo ee ee 90 89 87.5 
Sublimed blue lead........0..ccccccccenes 9 9 8 
‘Dordtmise-blue..22 3 oo ee ee 93 1.88 71.5 
Ultva-maring blue: .3..2. sa ees 88 88 85 
Chrome ereencnf i ee, ee 2 aioe 
CP, SECC ee eae ee 7 ¥ De 
Cy. P; green miedittiy 302 ae eee 5 6 5 
C.-Po green darks oe te eee fi ‘é Ls 
Pine. @reén jo sn ee 5 3. 
Chromium oxide: 22 ene 19 12 10 
Madder lake.vn cursus So eee Aas 1557-28 20 
American ochre. 7. i..0. a wae eee on 29 Ri 
Ochre: Anis eee 40 31 26 
Orange mineral osoio) Gs ie ae 65 63 55 
Para toner is. co to eee 8.5.0 8.5 
light para toners > 302) se eee De 49 s1S 
Alpha naphthylamine......0.000.0........... 645.) 632 ST 
Pigment-scarlet tomer: <o... > ae 70 67 62 
Pigment scarlet on gloss white........ 95 91 82 
Red leads). tro A ae es ae ee 67 67 65 
wearlet lead chromate... 25. 65 60 3 
Mercurie sulphate s.4). ee 72 71.5] 69 
Iron:oxide #3) Va.7 ae ee 50 52 52.5 
Irom omde! (03. tis eee 15 18 19.5 
Iron oxide 909, ie ee ene 2,54 VS eas 
Tron. oxide: O80 2 Ge. age 0 0 iS 
Metallic brown, 50% iron oxide...... 45 44 42 
Rawesienig. See HL 24 ri 
Dirtat sientigic yeu ee 1 5 » 
Cadmium Lithopone....i,...05 004 4.. 17 17 16 
Zine chrome es 0c ee een 35 33 32 
Chrome yellowiin: 7 ee 11 13 14 
Medium yellow. vi ae ee ce 3 4.5| 6 
Rawoumber kone. eee ae 29 26 24 
Burat- inert cht anaes 8 8 8 
Zinc dust (blue powder).................. G35 4] sou 50 


3342 


at Wave-length ~ 


3131 | 3023 
41 | 40 
0 0 
16 14 
40 | 36 
O27 ees 
10 4.5 
82 80.5 
0 0 
68.5| 68 
77 75 
0 0 
2 1 
1 0 
2 i 
6 6.5 
105-11 
Zz 0 
26° 7295 
26:51 26 
41 38 
7 6 
62 | 64 
40 | 36 
mi ieee ee: + 
68 | 66 
60 | 59 
55. ae 
63°) GL 
BK ae 
20 2) au 
2.5: te 
0 0 
36 | 34.5 
om | 20.5 
1 1 
13 1 Os) 
32:3) Sie 
14 14 
8 8.5 
29.o] he 
8 8 
44 | 43 


at Which 


Oe eer ee ee 


Ultraviolet Light Studies 189 


by timing the rise of the air bubble in the tube and assuming 
the rate of rise to be inversely proportional to the viscosity.* 


L4 Macbeth 
/luminome fer 


Llensl \ 2? 
) I nolL hs 
as oy 
Glass Prism . 
Cel/ Uranium Screen 


Quartz Tonochromator 


FIGuRE 70 


Apparatus for Determining Light Absorption by Oil 


‘‘As a further means of studying the action of ultraviolet 
light and the changes it accelerates, the degree to which such 
hght is absorbed by the oil was measured. This absorption 
was determined in the wavelength interval from 3655 A. 
to 2300 A., using an ultraviolet spectrophotometer. <A dia- 
gram of the apparatus, as used, is shown in Figure 70. 
Light from the quartz Uviare lamp passes through the quartz 
cell containing a thin film of oil and is dispersed in the Bausch 
& Lomb quartz monochromator. In order to measure visually 
the intensity of the ultraviolet light transmitted, A. H. Pfund 
suggested the use of a thin screen of fluorescent uranium glass 
cemented to a clear glass prism. The screen is viewed from 
above at an angle of 60 degrees or more, the lens L rendering 
parallel the Light from the foreshortened image of the slit. 
When so viewed the fluorescent light 1s particularly brilliant, 
and is easily photometered by means of the Macbeth illumino- 
meter. The intensity of the fluorescent hght is proportional 
to the intensity of the radiation falling upon the fluorescent 
sereen, and hence a direct measure of the ight transmitted by 
the oil film is obtained. By so viewing the fluorescent screen 
at an angle, no difficulty is experienced from ‘‘impure radia- 
tion’’ in the monochromator, since such ‘‘impure radiation’’ is 
due chiefly to longer wavelengths, not affecting the fluorescent 
screen. 

“The quartz cell, containing the oil, consists of two quartz 
plates, separated at one end by a thin strip of tinfoil. The 
angle of the wedge so formed, and hence the thickness of any 
portion of it, is found by measuring the set of interference 


Sisart, Phil, Mag., 1, 395 (1926). 


190 Ultraviolet Light Studies 


fringes obtained on reflecting monochromatic light from the 
two surfaces of the wedge. The transmission of several differ- 
ent thicknesses of each oil sample was measured to give check 


values. The degree of absorption shown by the oil is best 
expressed in terms of the absorption coefficient K caleulated 


from the relationship 


bes J10- 
where 7 = intensity of transmitted light 
I, = intensity of incident light 
t — film thickness in centimeters” 
TABLE 35 


Changes in Physical and Chemical Constants of Oils after Exposure to Ultra-Violet Light 


Exposure’ Refractive Iodine 
to U. V. Gas Viscosity index at oO. Acid 
light hours present poises Mol. wt 26° C. (Hanus) No. 
Raw Linseed Oil : 

0 0.4 173 1.4751 175 3.4 
12 Air 0.75 910 1A4TT5 171 4.5 
24 Air 12:5 1290 1.4779 117 TA 
30 Air 118.0 1785 1.4832 106 8.5 

3 Oxygen 0.6 969 1.4753 169 3.7 

6 Oxygen 2.25 1551 1.4786 127 7.0 

9 Oxygen 22.0 1858 1.4815 113 9.4 

9 Nitrogen 0.55 788 1.4750 160 3.5 
PAE Nitrogen 2.85 — 1.4785 149 5.5 
36 Nitrogen 5.25 1220 1.4803 113 5.5 

Perilla Oil 

0 0.50 762 1.4773 181 11.0 

3 Oxygen 0.65 844 1.4780 154 ED 

6.5 Oxygen 5.25 1364 1.4839 143 14.7 

9.5 Oxygen 33.0 1930 1.4851 116 15.0 

Poppy-Seed Oil 

0 0.55 1.4692 123 5.5 

4 Oxygen el 1.38711 123 5.9 

8 Oxygen 4.60 1.4747 105 11.6 
12 Oxygen 5.25 1.4750 87 12.4 

Soy Bean Oil 

0 1.0 1.4706 119 8.0 

8 Oxygen 2.0 1.4730 114 9.5 

8 Oxygen ef 1.4750 3 lal? 8.5 

Castor Oil 

0 4.95 1.4729 81 Tol 
18 Oxygen 5.45 1.4738 70 2.3 
36 Oxygen 18.07 1.4749 — 11.6 
54.5 Oxygen 47.50 1.4759 70 28.0 


Testing the Oxidation Effects of Ultraviolet Light.—State- 
ments have been made in the literature from time to time, that 
the chalking of lithopone is due to the oxidation of zine sul- 
phide to zine sulphate, and that the latter, being water solu- 
ble, leaches out and accelerates the weathering of the film. 
These statements, however, have never been accompanid by 
experimental data. 


In order to get some information on the subject, a series of 
paints were made up in this laboratory with 60 per cent. of 
pigment and 40 per cent. of liquid, the liquid containing 80 


» . 
oi 


Ultraviolet Light Studies 191 
per cent linseed oil, 15 per cent turpentine, and 5 per cent of 
lead-cobalt liquid drier. These paints were poured into por- 
eelain evaporating dishes 14 em. in diameter. The excess 
paint was then poured out. The dishes were allowed to drain 
for an hour. The dishes were then placed in direct sunlight 
for 3 days for drying of the coatings. In practically every 
instance, the weight of the dried paint added to the dish was 
from 4 to 5 grams. The area exposed in every instance was 
200 sq. em. The evaporating dishes were then half filled with 
distilled water (approximately 100 ec.). One set of the dishes 
was placed in the window, exposed to diffused daylight and 
to air currents for a period of 8 days. The other set of dishes 
was exposed under an ultraviolet are of the mercury quartz 
type, for a period of 50 hours. During these exposures, the 
dishes were subjected to slight rocking every hour in order to 
wet the coated sides above the water surface. At the end of 
the first eight hours’ exposure, qualitative tests, showed the 
presence of metallic compounds and sulphate radicles in the 
first three products tested. 

At the end of the tests, the liquid in the dishes was very 
carefully filtered and the percentage of metal determined. The 
results are given in the chart below. 


Grams zine in water Grams lead. in water 


solution solution 
(ei ae a i, mee oe 
Ultraviolet Ultraviolet 
Daylight light ex- Daylight light ex- 
exposure posure exposure posure 
8 days 50 hours 8 days 50 hours 

Oe 5 ED 2% 0.011 0.021 ‘ 
Mamgeesuipuige Paint.............. 0.004 0.017 
Mer PAINE... ee ee ee ee eee 0.003 0.014 es ae, 
White Lead (Carbonate) Paint... .... Bae 0.003 0.004 


It would appear from these results that while paint 1s assum- 
ing its final period of hardening, after the initial drying for 
three days, the presence of water and light may accentuate 
the development of soluble compounds. It is probable that 
the reactions which take place may to some extent be at- 
tributed to the formation of free acetic or similar acids by the 
drying linseed oil, and that these acids react with the pigments 
present in the films to produce water soluble materials. That 
zine sulphide may be oxidized to zinc sulphate is apparently 
also possible. The fact, however, that white lead, which con- 
tains no suphate radicle, becomes soluble to some extent, 
would further strengthen the theory that during the drying 


192 Ultraviolet Light Studies 
Sn een 
process, formic, acetic, or other acids of the aliphatic series 
are developed, and that they react with the pigments present. 
In the above tests the white lead afforded as much water solu- 
ble constituents as the lithopone paints, under daylight ex- 
posure, 


That ultraviolet light greatly intensifies the production of 
these water soluble products would appear from a study of 
the results given in the chart. It is probably safe to assume, 
however, that any pigment which is soluble in acids may under 
abnormal conditions of exposure to sunlight or moisture de- 
velop shght traces of water soluble compounds. It might, 
however, be unsafe to state that the small quantities developed 
were sufficient to cause chalking. 


It is probable that the above method of studying paints 
may prove of service to those who have had problems in con- 
nection with the ‘‘washing’’ of paint. Washing usually takes 
place on paints which have been applied in damp, cold weather. 
Such conditions retard the drying. Moisture is absorbed by 
the film. It apparently forms an emulsion-like gel during the 
prolonged period of drying. It is probable that this period is 
the critical one, during which acids are developed by the dry- 
ing oil. If these acids are retained within the film, it is very 
likely that soluble salts are formed, which later are indicated 
in the form of washing; the paints developing, when rubbed 
with the finger in wet weather, a soap-like, chalky emulsion 
which may readily be removed. The use of either strong 
driers, high pigment concentration, or oils of more rapid set- 
ting and hardening properties, is suggested. 


Darkening of Pugments by Ultraviolet Light—For results 
on lithopone, the reader is referred to Chapter XIV and to page 
215 for results on a number of commonly used pigments. 


CHAPTER XIV. 


TESTING THE LIGHT-RESISTANCE OF LITHOPONE 
Erect oF AcIpITty oF VARNISH AND OIL 


The darkening and discoloration of lithopone, due to the 
action of ultraviolet rays in sunlight, have in the past consti- 
tuted a serious drawback to the use of this pigment in paints 
and enamels. During recent years, however, continued re- 
search on the part of lithopone manufacturers has resulted in 
the development of much more light-resistant products, as 
well as great improvement in other qualities. 


The light-resistance of lithopones has been the subject of 
numerous investigations. There is much difference of opinion 
among the investigators regarding the nature of the change 
and the causes of it. The present chapter, however, is limited 
to a discussion of methods for testing light-resistance. Other 
physical properties of the samples tested, such as oil absorp- 
tion, fineness, livering, etc., are treated elsewhere. 


The comparative light-resistance of different samples is 
readily determined on clear days by exposing them in a suita- 
ble liquid, on properly mounted panels, to the sun’s rays. Fre- 
quently, however, atmospheric conditions are such that sun 
tests cannot be carried out. Moreover, the intensity of the 
active rays and the relative humidity of the atmosphere varies 
greatly at different times and in different localities. It is 
therefore highly desirable to have an artificial light source 
from which the ultraviolet radiation can be maintained con- 
stant and which has actinic effects similar to sunlight. Hu- 
midity, temperature, and other variable factors should be 
under control. ; 

The quartz mercury vapor are has been extensively used for 
testing the light resistance of paints, pigments, and dyes, and 
is a standardized piece of apparatus. As a means of making 
control tests in lithopone manufacture, it has been found very 
practical. More recently the iron are has been adapted for 
this purpose. It is believed that the iron are, when properly 
constructed and fitted with the necessary devices for regulat- 
ing and controlling the current, will also prove satisfactory 
In paint and varnish plant laboratories for certain types of 
work. It can be readily constructed at a very reasonable cost 


194 Light Resistance of Lithopone 


and produces a light practically constant in the intensity of the 
ultraviolet radiation. The chief advantage of the mercury 
vapor lamp is the large area of the light source which permits 
of the testing of large samples or a number of small samples 
at the same time. However, the proportion of ultraviolet rays 
transmitted through the quartz tube of the mercury lamp de- 
creases continuously with age (see Scientific Paper No. 330, 
U. S. Bureau of Standards). 


Before describing the results obtained in our investigation 
with the iron are, there is presented herewith a paper on the 
testing of lithopone, originally prepared for this chapter by 
Messrs. Breyer, Nelson and Farber. They point out the use- 
fulness of the quartz mercury vapor lamp as against the iron 
are, and refer extensively to the testing of all samples of litho- 
pone in the paint liquids in which they are to be applied in the 
form of paints. The information they transmit regarding the 
effect of high versus low acid oils upon the darkening of litho- 
pone is of exceptional importance. 


Inght Resistance Test for Lithopone-—A sample of three 
grams of the lithopone is rubbed down to a stiff paste in one 
part of China wood oil vehicle (a common type of China wood 
oil—rosin combination vehicle containing lead dryer) and one 
part naphtha. (Always make the test in the vehicle in which 
the lithopone is to be used, or at least in a vehicle of the same 
type and properties as the vehicle to be used.) The mixture 
of oil with thinner is freshly prepared for each set of tests. 
The paste is spread on a porcelain plate or palette in a smooth 
even layer, at least one inch by three inches in area. A stand- 
ard, or standards, should be run with each set of samples, all 
being prepared in the same manner. Care should be taken 
that the pastes of all samples are approximately of the same 
consistency. If paints are tested use the paint as it comes 
from the can. 


The palette is put in a warm place and the pastes dried 
until the glossy surface disappears. (In ease the testing is 
done in a vehicle yielding a gloss surface, such as a gloss white 
paint, dry until the surface will stand being submerged in 
water.) A strip of opaque black paper or a rule is laid across 
and above the samples to shadow a portion, and the samples 
are then exposed to the ultraviolet light under a thin layer of 
water 1/52 inch to % inch deep. (Exposure under water in- 
sures a uniform relative humidity.) A desirable length of 
exposure to bring out significant differences in lithopones is 


Light Resistance of Lithopone 195 
SN Sse 
five minutes at a distance of twelve inches from the light, when 
the current is 4 amperes at 180 volts across the line. 


Description of Light Used for Testing —The light source 
found to be most satisfactory for laboratory testing is the 
Standard Uviare Laboratory Outfit, manufactured by the 
Cooper Hewitt Electric Company, shown in Wie ie Phis 


{ 


3 . 


Al ea 


come 
: 


se me ™ a 


dp 


FIGURE 71 


Uviare Laboratory Outfit. Composite Detail showing 
showing two positions of hood. burner holder with 
Lorizontal type 

burner in position. 


equipment is furnished for either 220 volts direct current or 
110 volts alternating current. So far it has been considered 
Superior to other forms of equipment for routine tests on 


196 Light Resistance of Lithopone 


denne errr eee 


account of its simplicity of operation, being practically self- 
regulating. 

The details of the burner and holder are also shown. The 
burner holder is universally adjustable in all planes and will 
take either the vertical or the horizontal type of burner. 

The useful life of a quartz burner has been found by experi- 
ence to be from 1000 to 1500 hours of steady operation, and a 
new burner can easily be substituted. In practical laboratory 


FIGURE 72 


(A) Uviare light test on seven Lithopones. Time, 5 minutes. 


test work this provides an amply uniform source of light. A 
burner in use at the time this is written has been used for test- 


mes orane of samples daily for 114 years and is still considered 
useful. 


Light Resistance of Lithopone 197 


Also, since in any ease all tests are run against a standard, 


the behavior of the standard quickly indicates any falling off 
in the effectivesness of the quartz burner. 


Uviare Tests Comparable with Sunlight Tests Experience 
has already proven that tests carried out in the above manner 
are comparable with sunlight tests, and are a true indication 


[Sun Light. 


FIGURE 73 


(B) Sunlight test on seven Lithopones. Time, 2% hours. 


of light resistance. This is also demonstrated by the photo- 
graphs in Figs. 72 and 73. In these tests seven different litho- 
pones of varying light resistances have been submitted (a) to 
ultraviolet light, as described above for five minutes, and (b) 
to bright sunlight for 214 hours (sample under water). It 


198 Light Resistance of Lithopone 


will be seen that in each case there is perfect agreement in the 
relative light resistance of the lithopones. 


Humidity Must be Controlled During the Test Period.—lIt 
is a well-known fact, as indicated by the literature on actinic 
effects, that the presence of moisture increases the rate at 
which chemical changes are promoted by ultra-violet radia- 
tions. This is true of the darkening of lithopones. It is, 
therefore, very important that all comparative tests of this 
nature be conducted under known and reproducible humidity 
conditions. Since any condition short of complete saturation 
is not easily maintained constant or reproduced without spe- 
cial equipment, the simple expedient of immersing the samples 
in water is the most reliable means for eliminating the humid- 
ity variable from the test. 

We would also point out that testing under saturated moist- 
ure conditions has the further advantage that the lithopone 
is being tested under the most trying conditions it can ever be 
required to meet in practise. 


Effect of Vehicle on Results of Light Resistance Tests— 
Under the foregoing description of the test method it was also 
suggested that the vehicle is an important factor in the results 
of light resistance tests and that tests on lithopones intended 
for paint purposes should be made in a practical paint vehicle. 

A number of lithopone users have insisted that water or 
glycerol pastes should be used in testing for light resistance. 
From every standpoint this is wrong, unless the lithopone is 
actually to be used in water or glycerol vehicles. That such a 
method is fundamentally wrong and misleading is amply dem- 
onstrated by the tests in Fig. 74. 

In Fig. 74 the original lithopone is rubbed down in (1) regu- 
lar flatting oil test vehicle (2) water and (3) glycerol. There 
is no agreement in the results and, obviously, only the test in 
the oil vehicle can be accepted as a criterion for lithopones 
to be used in oil paints. 

Further, the use of water and glycerol pastes may lead to 


extremely erroneous conclusions about improvements in the ~ 


quality of lithopones. Lithopones can easily be ‘‘doped’’ so 
as to vary their light-resisting properties. In Fig. 74 the same 
lithopone has been so ‘‘doped’’ and tested in (4) flatting oil 
vehicle (same as above), (5) water and (6) glycerol. It is 
important to note that while this lithopone now shows per- 
fect light resistance, in both water and glycerol pastes, there 
has been no improvement with the flatting oil vehicle. There- 
fore, it would be a mistake to say that the quality of the litho- 
pone had been improved. 


Light Resistance of Lithopone 199 


Preferable to Test in Same Oil Vehicles as Used in Practice. 
—The light resistance properties of lithopones are also affected 
by variations in the properties of the oil vehicle themselves. 
Fig. 75 illustrates how very important this factor may be. A 


Light Resistance test. 
Brpesed te Ultra Violet 


Lignt for five(5)minutes, 


Orignal 
Rubbed in oi 


= / 


Treated ; 
Rubbed 


* 


LPS rtemisinitics 


FIGURE 74 


Comparison of light resistance tests on the same Lithopone in (1 and 4) 
oil vehicle (2 and 5), water, and (3 and 6) glycerol. 


single lithopone was tested in a series of vehicles typical of 
the principal oil products on the market. (In these tests the 


200 Light Resistance of Lithopone 


Figure 75 i 

Acid Acid ; 

No. No. 3 

1. Raw Linseed Oil......... 8. Standard Acid Refined Lin- a 
2. Improved Raw L. Oil..... 5-7 seed Oil 4.5 Hage % 
3. Alkaline Refined Varnish 9. White Acid Refined Oil... 6.5 5 
OL. EP ae yo dee ake ee 10.. Pale: Grinding jcieees eee z 

4. Alkaline Refined Oil...... 0.5 11. Boiled Qi ty a scone q 
5. Alkaline Refined Oil Re- 12. Kettle Bodied ...5...4..2.5 ——= ; 
frigena ten s.io5) ay se oe 13. Blown Bodied Gilly 2p CU : 

6. Alkaline Refined Oil...... 3.0 14. Boiled Ol] sc. <2 eee bs 
7. Acid Ref. Oil Refrigerated 10 15. Treated China Wood Oil.. 5-6 7 
Light Resistance test on a Lithopone in yarious oil vehicles. : 

oils have been thinned with volatile so as to dry to a semi-flat- 
surface.) Very few of the results check one another. : 
If we consider the results further, we find that, generally, 
the important determining factors appear to be the acid num- ; 
ber of the vehicle, and whether the oils are acid or alkaline : 
i 


Light Resistance of Lithopone 201 


refined. The presence of acid materials apparently increases 
the light-resisting properties. 

Fig. 76 presents still further evidence that effects of changes 
in the properties of oils, which are brought about in the process 
of manufacturing, must be seriously considered as factors in 
choosing the vehicle in which to conduct light-resistance tests. 


: [Alkaline Refinea, Jo | 
#/ 


| Acid Refined, 


ads 


# 


[Kettle Bodied 


FIGURE 76 


Test further illustrating effect of vehicle treatment on the light resisting 
properties of a Lithopone. 


This effect of increased acidity is also illustrated in Figs. 77 
and 78 (A) and (B). (A) shows the effect of increasing acid 
numbers from 1.0 to 20.0 in an alkaline refined linseed oil. The 
acidity was increased adding linseed fatty acids. (B) com- 
pares a treated China wood oil vehicle with a series consisting 
of increasingly acid raw China wood oils. Fatty acids of 
China wood oil were added to increase the acidity of this 
vehicle. 

That commercially used flatting vehicles might differ very 
widely in their influence on the light-resistance properties 


202 Light Resistance of Lithopone 


Acia Number 1.6 


Acid Number 5&,9 


Acid Number 10,0 


* 


Acid Number L5,0 


Acid Number 20,0 . 


FIGURE 77 


(A) Alkaline Refined Linseed Oil. 


of a lithopone, follows as a natural deduction from what has 
just been said. But this is more forcefully demonstrated as 
an actual fact by the tests with two flat wall vehicles illus- 
trated in Fig. 79. In this case vehicle (A) probably is a com- 
bination of linseed oil with some China wood oil. The acid 
number of this vehicle averages about 13. Vehicle (B) is a 
straight treated China wood oil vehicle having an average 
acid number 5-6. 

All of the tests just presented suggest that certain precau- 
tions must be accepted as essential in making reliable com- 
parative light-resistance tests on hthopones, viz: 


(1) Always run the test lithopone sample against a standard 
or standards. 


(2) The humidity conditions must be maintained constant 
if different tests are to be considered at all comparable. 


(3) The test vehicle must be of the same type and similar 
in properties to the vehicle used in practice. 


(4) Watch the test vehicle for any variation in properties. 
This refers to variations in acidity, especially. 


ye = 
a on 


ef, ae ae 


Light Resistance of Lithopone 203 


Iron Arc Tests.—The results given in the following pages 
were obtained with an iron are which was designed, in its 
original form, by Dr. A. H. Pfund.* The intensity of the ultra- 
violet radiation varies with the current passing through the 
are. It is therefore necessary that the amount of current be 
properly adjusted by inserting a variable resistance in the line. 
The length of the are must be readily adjustable so that the 


| “nadea's os tty Welae Le Rew ch 


a Wood see if the tece 
She ac nate nunber Tease 
E ees Banter! meters 


Treated China Wood 


FIGURE 78 


(B) China Wood Oil Vehicle. 
Effect of increased acidity of vehicle on light resistance of a Lithopone. 


proper potential across it may be maintained. It has been 
found that the are constructed as described herein burns best 
at a current of five amperes with a potential of 40 volts be- 
tween the electrodes. 

The method used by the writer in making these tests was 
essentially that of Eastlack and Booge: who have furnished 
the following description. 


a. Principle of Method.—The sample of lithopone in the 
form of a water paste is exposed under a quartz cover glass to 


*Astro-physical Journal, Vol. 27, p. 296 (1908) ). 


204 Light Resistance of Lithopone 


oe 


§/11/21, 


he 


FIGURE 79 


Difference in the light resistance of a Lithopone in two commercial flat 
wall vehicles. (A) Probably a combination Linseed Oil-China Wood Oil 
vehicle. Acid Number 18. (B.) <A treated China Wood Oil vehicle. Acid 
Number 5-6. 


the action of a standard iron are, at a distance of 10 em. A 
portion of the sample is covered with opaque material. The 
time required to produce the first appearance of darkening, 
as indicated by a faint but definite line of demarkation be- 
tween the exposed and unexposed portions of the sample, is 
taken as a measure of the light-resistance of the sample. 


b. Apparatus and Materials Required: 

Iron are with voltmeter, ammeter and rheostats. 

Sample holder with an optically clear dise of native quartz 
crystal (30 mm. dia. x 1.5 mm. thick).* 


Spatula—hard rubber, small. 
Beaker, 50 ce., or glass plate for mixing paste. 
Distilled water. 


*Comparative tests by three different laboratories (see below) indicates 
that exact adherence to the specifications for the quartz dise is important. 


al as Si os i ayy 


Light Resistance of Lithopone 205 


c. Procedure: 


1. Preparation of Sample.—Put 3-5 g. of the hthopone into 
a 50 ec. beaker (or on a glass plate), and about 2 cc. of dis- 
tilled water, and with a small rubber spatula mix the water 


ENE | S WSs = 


FicurEr 80 


Diagram of iron are equipment used in our work. 


and lithopone in such proportion that a smooth, moderately 
thin paste is obtained. Place a portion of the paste on the back 
of the quartz disc and press a small piece of glass down over 
the paste to prevent its drying out during the test. The sur- 


206 Light Resistance of Lithopone 


face viewed through the quartz dise should be uniform and 
free from air bubbles. Place the plate carrying the dise in 
the sample holder at a distance such that the surface of the 
sample is 10 em. from the center of the are. Cover a portion 
of the sample with a strip of thin brass or other opaque 
material. 

2. Starting and Operating the Arc.—Before starting the 
are see that the upper electrode is fairly free from ferrie oxide 
and is adjusted to extend 14 inch to %% inch below the radiator 
and is centered directly above the lower electrode. Now close 
the main switch, bring the electrodes into contact with each 
other and quickly separate them—thus starting the are. 


The shallow cup on top of the lower electrode should be 
completely filled with a bead of magnetic oxide. If this is 
not the case, raise the current to about 10 amperes until the 
top of the upper electrode is in a thoroughly molten condition. 
By quickly bringing the electrodes into contact and then sepa- 
rating them again, the drop is transferred to the lower elec- 
trode. The 10-amp. current is then maintained until the top 
of the upper electrode is again molten, so as to obtain a sym- 
metrical bead on the upper electrode also. 


Now cut in resistance until the current is adjusted to exactly 
9 amperes, using the large rheostat for coarse adjustments 
and the small rheostat for fine adjustments; also adjust the 
distance between the electrodes until the potential between 
them is exactly 40 volts.* | 


3. Exposure of Sample and Interpretation of Results.— 
When the arc is operating smoothly at 5 amperes and 40 volts, 
open the shutter, exposing the sample to the are, and close it 
again at the end of 30 seconds. Examine the sample care- 
fully in a good light to see if the exposed portion has been 
darkened (as indicated by a line of demarkation between the 
exposed and unexposed portions). If not, another portion of 
the sample is exposed for 60 seconds, or, if the sample was 
appreciably affected in 30 seconds, the next trial is made at 
15 seconds. For each exposure the position of the strip of 
brass protecting part of the sample must be changed. 


Repeat the exposure of the sample to the are (using fresh 
portions of the paste, if necessary) until the time required to 
produce the first appearance of darkening has been satisfac- 


*In a private communication Pfund and Eastlack state that a somewhat 
steadier arc may be obtained by using a current of 35 volts and 6 amperes. 
This gives about the same wattage and therefore the Same intensity of light 
as a current of 40 volts and 5 amperes. 


at 


Light Resistance of Lithopone 207 


torily determined. The precision which is regarded as satis- 
factory for exposures of different lengths is indicated below: 


Total time for 1st “End-Point” should be 

darkening. located within— 
Se nace oles os sk ss vias op ceeded ccccccccunce 1 sec 
sls eco s cs me sont sc ove vce ode cons ccececuc, Ps 

a ee eal gs iobia's ves ev vies dela oe cca bance cay Bes 

MS 0S aie Ss kk vice cn cc ess wo ecckcanccnncn. LO. 

I ee. Loic cig.ds s's os nk vv eso dooce cecseccwer PAW ak 

oo vig eek os esis ale Gc ev be 0s boehckiede 30 


The number of seconds required to produce first darkening 
is recorded as a measure of the light-resistance of the sample. 
Samples which show no darkening in 300 seconds (5 minutes) 
may be regarded as ‘‘light-stable,’’ although for all practical 
purposes samples which show no darkening in 60 seconds will 
not be appreciably affected by sunlight when used as a pig- 
ment in oil paints. 


Inthopone Samples Examined.—In the work carried out by 
the present writer, four series of samples were tested. They 
are designated as follows: | 

Series A: Laboratory samples. A-1, A-2, and A-3 were 
originally obtained for specific gravity work and were about 
four years old. The other samples of this series were from 
two to three years old. None were obtained for light-sensitive- 
ness tests. 

Series B: Set of five samples of varying degrees of light- 
sensitiveness obtained from the Bureau of Standards which 
had been sent to the Bureau by Dr. Booge. 

Series C: Standard samples of varying degrees of light- 
sensitiveness sent by Dr. Booge. 

Series D: Samples from factory batches obtained direct 
from the manufacturers. These represented current com- 
mercial lots. 

Tests on Water Pastes of Lithopones.—As pointed out in 
Hastlack and Booge’s communication, lithopone is far more 
sensitive in water paste than in any other vehicle. When ex- 
posed to the sun’s rays some samples darken perceptibly in a 
few minutes, while all except one of those examined were more 
or less discolored at the end of one hour under prevailing at- 
mospheric conditions. Darkening under the influence of the 
iron are is sometimes a question of seconds only, while very 
few samples will stand exposure for ten minutes without 
discoloration. 


Results obtained with the iron are on water pastes of the 
twenty-five samples examined are given in Table 36. 


208 


Light Resistance of Lithopone 


In Table 37 are given the results of tests on series C and 


series D upon exposure to the iron are and to sunlight. 


The 


samples are arranged according to increasing light resistance. 
The table indicates that for water pastes the order of darken- 
ing, in general, is the same by the two tests. 


TABLE 36 
Iron Arc Tests—Water Pastes 

Sample Time for 

No. darkening. 
Fe Ge ee re ee OM ETON 6 seconds 
| ee Nir Peet 20 seconds 
AWB oe eb nee ee lb ony Gee woe Sle le oelpoai ua lors bi epee es eg a 5 seconds 
De ee ene ere IE PRM EARE RPK 60-70 seconds 
AD col cece wa bebe da waders ew ele eles piecelece ss@ie at Sie. 4 seconds 
7: eee ee REEL 650-700 seconds 
AMT Sc cine cie ae cee ecw ewe ep cw a whats Mvaitee oa toe ie ita a 6 seconds 
to, a ME PI er 250-800 seconds 
Baloo .4 5 oka be ek a eee ee unaffected in 1200 seconds 
Boo cos vc cee ee oe aca eee Wik O° ag 5 a aibaael aap eee a 150 seconds 
1 5 os ee re ea 30 seconds 
Br sc sce cee oe cee wie a eu wie coe gu 6 alop ip wlelie aie see 16 seconds 
BR ie Ske bie cis nie cle ys won gio ale em ale te Senate een er 4 seconds 
CPD ble eck wna weedane reap geen unaffected in 1200 seconds 
0S) an re MRE 135 seconds 
CO-B nies vee occ nc 6 oc3.8)e.ce hin ee, psoite oiete glare a a aieaicet atest 40 seconds 
De4 ec bine oe eee wn wip 0 asa win a nw ooh eile a gilin cs inet a 18 seconds 
CHB ok hk cen we la e's) oc pre apna ele le @ ele a abe) eiea: GleAy ie geen i 4 seconds 
LO ra rrr me ge 95° seconds 
D8 ook baie since ww wwe 08 we wy ncn ee an ge leah ee eae 240 seconds 
D-Backs ae we md eie'a bes ew Siw le ie kn uel gel gen 85 seconds 
D-4 en vee oe on deeb 6% ge Dy Se gies ae lel ec apr eee 1200 seconds 
DB ipa cae ie hen eon en bbw oe lela © alec big) Gln ene ligne iene 950 seconds 
| OS 5 arr mrer ar are re rE Be 30 seconds 
DoT iis ep ware oe win we, gnlay wk we pleiy, vault te ee eae a 600 seconds 


TABLE OU 


Order of Darkening—Water Pastes of Lithopone. 
Slides for Sunlight Tests Prepared According to the Method of Hastlack 


and Booge. 
Sunlight tests. 


oh FF 
Color after one hour 


Sample. exposure to sunlight. 
CE oihoe aheie cede A ate edo Almost black 
OSE iy lal wie a nN tee ee Very dary gray 
D8 2s Lae ee ree en ee Dark gray 
COD: new elvan ee OOS eR Dark gray 
Teh at REPRE Att ete, seca ehatangter s Yellowish gray 
| Ee a Oe er pe ga Man es ee Gray 
CTD Sal geal Grp cote ae I gee Yellowish gray 
DIZEE iee a asst patente ee Gray 
DS Sr ee sae reat era Gray 
DAO on po ow eee earns are ees Slightly gray 
Tris eee aceaeani es Se ae ieee ee Very slightly yellow 
CA imate eek a Sek ca Very slightly yellow 


Iron Are Tests 
ease ae ,.| 
Time for darkening. 
4 seconds 
18 seconds 
30 seconds 
40 seconds 
85 seconds 
95 seconds 
135 seconds 
240 seconds 
600 seconds 
950 seconds 
1,200seconds 
Unaffected in 1,200 seconds 


Light Resistance of Lithopone 209 

The day on which the sun exposures were made was very 
hot and the sky somewhat hazy but not cloudy at any time 
during the exposure. 

The discoloration of samples D-7, D-4, and C-1 in the. sun 
tests faded completely in a few hour s. The rest remained 
permanently darkened although D-2, D-6 and C-3 faded out 
to a considerable extent. 


Tests on Glycerine Pastes of Litho pones. —Lithopones will 
also darken when glycerine is used in place of water in mak- 
ing the paste. The time required for darkening is somewhat 
greater than for water pastes. Table 38 gives the results ob- 
tained on the samples of Series C. 


TABLE 388 
Iron Are Tests on Glycerin Pastes. 
I ed Ly vciwleis vee vleeceacwees Unaffected in 1,800 seconds. 
I Te cc cee eee eee Darkened in 720 seconds. 
he ek ie ews PE ee eh ee View gies we wie’ Darkened in 120 seconds 
SE I a Darkened in 45 seconds. 
ae twee dt ew eases eves Darkened in 12 seconds. 


TABLE 39 


Sun Tests on Dammar Varnish Pastes 


Final Order 


Sample 2 Hours 5 Hours 12 Hours 20 Hours of 
Darkening 
ee 
D-1 Unaffected Unaffected Very slightly Bluish gray C-5 
darkened darkest 


bluish gray 


oe eee es el eee 


D-2 Unaffected Unaffected Unaffected Apparently C-4 


unaffected 
D-3 Unaffected Unaffected Very faintly © Gray D-6 
darkened 
a a nce 
D-6 Unaffected Slightly Somewhat Quite gray C-3 
affected darkened 
Eee 
C-2 Unaffected Unaffected Faintly Slightly D-1 
darkened bluish gray 
C-3 Very slight Slightly Somewhat Quite gray D-3 
indication darkened darkened 
IS ces 
C-4 Very slightly Somewhat Dark gray Very dark C-2 
darkened darkened gray 
C-5 Slightly Very dark Bluish black Bluish black D-2 


darkened gray lightest 


I~ a anna 


210 Light Resistance of Lithopone 


Tests on Varnish Vehicle Pastes of Lithopones.—Some 
manufacturers and users of lithopone rightly prefer to make 
the test in oil or varnish vehicles in order to more nearly 
approximate actual service conditions. 

Tests were also made to determine whether the results ob- 
tained in water pastes would run parallel with the results of 
sun tests on pastes in oil or varnish vehicles. For this pur- 
pose Dammar Varnish and also a commercial flat wall paint 
liquid were used. The tests were made on eight representa- 
tive samples which darkened when exposed to the iron are, in 
varying periods of time. The results of these tests are given 
in Table 40. 

It will be observed that the order of light stability shown in 
this table agrees well with that of Table 37. Since there is no 
sharp point or narrow limit of time in which darkening can 
be said to occur in the sun tests, and moreover, the color of the 
discoloration varies considerably with different samples, slight 
discrepancies are to be expected. 


TABLE 40 


Sun Tests on Flat Wall Paint Liquid Pastes 
eee eee 


Final Order 
Sample 2 Hours 5 Hours 12 Hours 20 Hours of 
darkening 
eee 
D-1 Unaffected Unaffected Very faintly | Somewhat C-5 
darkened darkened darkest 
yellowish 
gray 
D-2. Unaffected Unaffected Unaffected Apparently C-4 
unaffected 
D-3 Unaffected Unaflected Slightly Slightly D-6 
yellow 
D-6 Unaffected Unaffected Faintly Quite yellow D-1 
darkened 
nnn OMEN 
C-2. Unaffected Unaffected Faintly Slightly C-2 
darkened yellow 
C-3 Unaffected Unaffected Apparently Very light D-3 
unaffected gray 
C-4 Unaffected Unaffected Very slightly Yellow C-2 
darkened 


C-5 Very slightly Very dark Very dark Almost black D-2 
darkened brown brown ~ lightest 


AS lee 


atye = 


ae eae aad eee 


Light Resistance of Lithopone 211 


Efforts were made to check the sun tests on Dammar var- 
nish and flat wall paint liquid pastes with iron arc tests. ‘The 
time required for darkening in these liquids is, however, so 
great as to make the iron are rather impractical for these 
pastes. The results obtained are given in Table 41. 


TABLE 41 
Iron Arc Tests on Paint Liquid Pastes 
Time required for darkening Time required for darkening in 

Sample in Dammar varnish paste flat wall paint liquid paste 

ae ae Unaffected in 3,600 seconds Unaffected in 3,600 seconds 
2 a ae Darkened in 500 seconds Darkened in 1,400 seconds 
OE a Unaffected in 3,600 seconds Unaffected in 3,600 seconds 
TE ee eee Darkened in 3,600 seconds Unaffected in 3,600 seconds 


Comparison of results obtained in different laboratories.— 
Light stability tests were made on the samples of series B and 
series C in water paste. Similar tests were also made by 
Eastlack and Booge, and at the Bureau of Standards. Results 
obtained in three laboratories are given in Table 42 for the 
sake of comparison. 

The apparatus used by the writer and by Hastlack and 
Booge are described above. The following description of the 
apparatus used at the Bureau of Standards was submitted by 
Dr. J. G. Thompson, who made the tests, the results of which 
are given in Table 42. 

Thompson Arrangement of Apparatus.—The source of 
ultra-violet light was a small iron are operating at 5 amperes 
and 40 volts. The electrodes were ordinary soft-iron rods. 
The dry samples were rubbed up to moderately thick pastes 
with water, using a rubber spatula. The paste was spread on 
one side of a plate of crystalline quartz aproximately 1 inch 
x 21% inches x 14 inch thick. The quartz plate was mounted 
in a holder so that the ultra-violet light must pass through 
the quartz to reach the paste, the quartz-paste surface being 
10 em. distant from the center of the are. The remote sur- 
face of the paste was covered with a glass microscope slide to 
prevent too rapid evaporation of the water. 

The results reported are average values based on more than 
one determination. 

The cause for the discrepancies is not yet apparent, but is 
probably due partly to errors of observation in judging the 
time required for first darkening. Some operators can detect 
fainter shades of darkening than others. Hastlack and Booge 


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Light Resistance of Lithopone A kes 


have found that the composition of different types of iron 
rods forming the electrodes has only a slight influence on the 
results. Probably the greatest source of error arises from the 
fact that different pieces of quartz used vary in their trans- 
parency to ultra-violet light. 

According to Luckiesh* crystalline and fused quartz differ 
considerably, the crystalline variety usually being transpar- 
ent further into the ultra-violet region than the fused. Differ- 
ent crystals also vary considerably in transparency. The 
writers used a dise of fused quartz one inch in diameter and 
one-eighth inch thick. In order to determine whether the 
particular piece of quartz used would affect the results to an 
appreciable extent, the writers borrowed the piece which had 
been used at the Bureau, using it in connection with their are. 
The results checked those of Thompson’s quite closely as 
shown in Table 43. The lower values obtained by Eastlack 
and Booge are no doubt due to their use of an optically clear 
quartz dise of only 1.5 mm. thickness. 


TABLE 48 
Results Obtained at Two Laboratories Using the Same Quartz Glass 
Institute of Paint and Var- 


Sample Bureau of Standards. nish Research 

No. 2 Darkens in 80-90 seconds Darkens in 8&5 seconds 
No. 3 Darkens in 30-35 seconds Darkens in 30 seconds 
No. 4 Darkens in 16 seconds Darkens in 14 seconds 
No. 5 Darkens in 4 seconds Darkens in 4 seconds 


The following comments were made by one observer to 
whom this chapter was submitted: 


Apparently temperature plays an important part in the 
eolor changes that take place when lithopone is exposed to 
sunlight or to ultra-violet light from laboratory lamps. It is 
considered that with rise of temperature to a certain extent, 
lithopone becomes less sensitive to change. Undoubtedly the 
condition of the atmosphere in which the tests are made has 
something to do with the effects. It has been found, for in- 
stance, that darkening is much more rapid in a hydrogen 
atmosphere than in ordinary air. Tests, however, indicate 
that darkening will not take place in an atmosphere of ozone, 
and in most cases will not take place in oxygen. One investi- 
gator some time ago rubbed up a sample of lithopone in water 
on a glass slide, and placed it in a U viol tube having a 2-hole 
rubber stopper, through which moist hydrogen was bubbled. 


*Ultra-violet Radiation, page 73 (1922). 


214 Light Resistance of Lithopone 


The slide was exposed to the light of a Macbeth printing lamp, 
specially cored carbon rods being used. It was found, for in- 
stance, that even zinc oxide would darken under these con- 
ditions, as well as certain copper salts, and the result was 
attributed to a reducing action. 

It has been known for a long time that lithopone may be 
made sunproof when ground in water paste, by the addition of 
small amounts of salts, such, for instance, as ammonium phos- 
phate. However, when the same mixture is dried and mixed 
with oils and exposed it is apt to darken very rapidly. 

In commenting upon the tests outlined in this paper, an- 
other well-known investigator gave the following information: 


‘“Sunlight Test—We keep the samples moist by putting the 
glass slides on a piece of common blotting paper, kept moist 
by a small glass jar filled with water, and a cotton wick leads 
from the glass jar and is laid upon top of the blotter. In this 
way we have found we could keep samples moist for two or 
three hours, which is sufficient to get a good sun test. 

We have found that glass once used will absorb energy from 
the sunlight, and if this same glass is used for a second test 
the lithopone, if it is very sensitive to light, will turn without 
being exposed to the sunlight. We therefore make it a point 
to use new glasses for sun tests all the time. Using a glass 
which has already been exposed might make a lithopone 
turn in 15 minutes as bad as it otherwise would in 30 minutes, 
and thereby give you a wrong test. 


“Comparison with Paint-Out Tests——We have found the 
humidity is the main factor in making lithopone paints turn in 
sunlight. We have made hundreds of experiments with flat 
wall paints and gloss paints, and find the flat paints to turn 
much quicker than gloss, and if the humidity is below 60 per 
cent. the modern lithopones will not turn at all, while the old 
lithopones will turn as black as coal. These tests are made on 
pine boards painted with regular flat or gloss paint, one-half 
covered ite paper, the other half exposed to the sunlight on 
the south side of our laboratory.”’ 


Concuusions.—The light resistance of lithopone may be 
tested by exposure either to sunlight or to an artificial source 
of ultra-violet light. Tests made on a number of samples in- 
dicate that the two methods yield concordant results. While 
the order of darkening of a series of pigments is the same by 
the two methods, a considerably longer time is required for 
the sun tests. 


~ ae 


Light Resistance of Lithopone rg 


enn ere ee rr 


For research work where there is trained personnel, the iron 
are could be a supplementary part of the laboratory equipment, 
since the intensity of the ultra-violet radiation can be main- 
tained most constant over a long period of time. For this 
reason, the iron are could be used to occasionally check up the 
intensity of the quartz tube mercury vapor lamp. In other 
words, it could be used as a standardization instrument. 


For ordinary paint factory use, it is suggested that litho- 
pone be tested in the liquid in which it is to be used in practice. 


For this purpose, a quartz tube mercury vapor lamp 1s most 
useful, because several samples of lithopone in different paint 


Hnuids can be exposed at the same time. In five minutes re- 
sults may be obtained and a photographic record made. 


Errrot oF Uurra-VIoLtet Light on Pigments OtTHer ‘THAN 
LITHOPONE 


The property of darkening when exposed to ultra-violet 
light is shown to some slight extent by other pigments than 
lithopone; in fact, even by some inert pigments. While sev- 
eral pigments examined, notably antimony oxide, showed a 
change, the effect is usually only a slight graying which is not 
ereatly accentuated by continued exposure to the light. While 
lithopone darkens most quickly in water paste, all other white 
pigments examined, if they changed at all, were most readily 
affected in glycerin paste. Results of tests on white pigments 
other than lithopone are given in Table 44. It was indi- 
eated by study of several samples that the presence of small 
quantities of water soluble salts or the effect of certain meth- 
ods of heat treatment were accelerators of darkening. 


TABLE 44 


Iron Are Tests on White Pigments Other Than Lithopone 
The term “darkening” refers to a slight “graying.” 


Sample Water paste. Glycerine paste. 
EE yk tne so ee ee eee Unaffected Darkened 
Basic Carbonate White Lead ....... Unaffected Darkened 
Basic Sulphate White Lead No. 1.... Unaffected Unaffected 
Basic Sulphate White Lead No. 2.... Darkened Darkened 
er ec ek ses sce eve sence ee Darkened Darkened 
ein 0 a Unaffected Darkened 
Soo. 6 5 y's ahs ee cc eos pe ofa as Unaffected Unaffected 
Te ep kes pace eves ee as Unaffected Unaffected 
Zirconium Oxide (Hydrated)........ Unaffected Unaffected 


Rs gle als ie  a'v.e's vie ve wiersherd ons ¢ Unaffected * Darkened 


216 Light Resistance of Lithopone 


Results on some colored pigments are given in Table 45. 
It is interesting to note that pigments high in lead oxide are 
apparently more subject to ultra-violet light effects than some 
others. For instance, dry litharge, even when placed in a glass 
bottle, will show on the surface some color change when ex- 
posed to diffused daylight in a laboratory over a long period 


of time. 


TABLE 45 
Iron Are Tests on Colored Pigments 
Sample. 

Toluidine Lake Scarlet. oo. 7s). ca scabee ee Unaffected in 1,800 seconds 
Tron: OF Me. SS ae ee ee eee Unaffected in 1,800 seconds 
Chrome Yellow  CBASi€) <i. ave.s5 asc oe Darkened in 1,500 seconds 
Lat Rare: eo ied s ecstasy ere 8 eee he oe ee Darkened in 45 seconds 

Light Chrome Yellow (Neutral)......... Unaffected in 1,800 seconds 
Réd Lead $s ck ks es ee a eee Unaffected in 1,800 seconds 
Chrome Orange....0s a. Wels eee Unaffected in 1,800 seconds 
Para ‘Toner icck os cs ee wae he oe eee Unaffected in 1,800 seconds 
Brilliant Orange Lake... 2.4.0: 05 see Darkened in 1,800 seconds 
Chrome. Yellow -Oranges." 3024.) ase eee Darkened in 1,800 seconds 
Ghroime: Green Ge Pic ies sa seats Faded somewhat in 1,800 
Prenssian. BING. 453 eee eee eee eee . Unaffected in 1,800 seconds 


Zing = Dustsc oh cstekoche Oo ee ee ee Unaffected in 1,800 seconds 


seconds 


CHAPTER XV 


COLOR SYSTEMS, COLORIMETERS AND SPECTROPHOTOMETERS 


Paint manufacturers have often felt the need of defining and 
preserving standards of color. The methods in use at the 
present time are unsatisfactory. The most widely used method 
of preserving standards of color is by means of painted color 
chips, which may exhibit a slight change over a short period 
of time, depending largely upon the conditions under which 
they are stored. The same difficulty is occasionally met in the 
ease of tinned standards either ground as a paint or ground 
in light-colored paraffin oil or in glycerin (see Page 255). It 
has been realized for some time that instruments were being 
made available by means of which a color could be recorded 
and the results kept for further reference. The majority of 
systems for color* measurement are open to certain complica- 
tions and difficulties of a fundamental character, particularly 
those dependent upon the use of secondary standards which, 
in themselves, have little or no definite relationship to each 
other and which could be translated into fundamental physi- 
eal units only by spectrophotometric analysis of each ind1- 
vidual color. Consequently little study has been given to them 
in connection with their possible use in the paint trade. 


In this chapter an attempt has been made to describe, clas- 
sify, and comment upon the various systems of color nomencla- 
ture and to indicate the usefulness and limitations of various 


colorimeters and spectrophotometers. That some of these in- 
struments will soon come into wide usage in the paint industry 
is believed probable. Some enthuisasts even believe that the 
curve obtained by reading a color upon such instruments may 


*Color as one perceives it in an object is simply psychological or 
optical sensation. We say, for instance, that lamp-black is black, and the 
Sensation produced is due to the fact that the physical structure of the 
pigment causes the absorption of nearly all visible light rays that fall upon 
it. When these same light rays fall upon zine oxide, they are practically 
all reflected and we say that this pigment is white. Similarly we have the 
sensation of red from a pigment absorbing all rays except those that give 
a sensation of red, while from a green pigment we have reflected only those 
rays that give the sensation of the particular hue of green that appears. 
How simple would be the preparation of all colors if we could so change by 
a simple process the physical structure of some element like carbon so that 
it would reflect red, green or blue in such proportions as to give the hue 
we desired. 


218 Color Systems, Colorimeters, Etc. 


be made the basis of purchase where exact standards are 
required. 


The descriptions and comments which follow are based, 
wherever possible, upon actual examination or operation of 
the method or the instrument. When this was not possible, 
the available literature on the subject was searched for the 
necessary information. References to original papers treat- 
ing the subject in much greater detail than was possible here 
have been given throughout the chapter. A list of some of the 
more widely known books on the subject of color in general 
will be found on Page 255 for those who wish to make a more 
detailed study. 


The writer is indebted to M. Rae Paul for valuable sugges- 
tions in reviewing this chapter. 


CoLor SyYSTEMS OR CHARTS 


Numerous attempts have been made to display on color 
charts or cards large numbers of colors arranged in a definite 
order. These color charts or color atlases, as they are some- 
times called, have a wide use where an approximate match is 
all that is required. The almost infinite number of colors has 
made it nearly an impossible task to make a series of color 
chips on which may be found any desired color. The inten- 
tion is not, however, to show every desired color, but to give 
a large number of colors, all bearing a relationship to each 
other and in the form of progression, so that if a sample can- 
not be matched on the chart it can be stated as lying between 
two adjacent colors in the system. Most of these color charts 
contain in the neighborhood of 1000 colors. | 


The authors of these systems have accepted certain theories 
of color arrangement and have made definite rules which have 
been followed throughout the charts. Following is a brief 
description and discussion of several of the more widely 
known of these systems which the writers have studied. 


Many of the charts described are very difficult to obtain and 
quite expensive. All of them, with one exception (Chevreul’s), 
may be seen at the Library of Congress in Washington. 


Maerz and Paul ‘‘Dictionary of Color.’’—A. Maerz and M. 
Rea Paul have recently published a Dictionary of Color which 
is intended as a reference for those who seek to relate colors 


Color Systems, Colorimeters, Etc. 219 


with the names by which they are commonly identified. The 
book contains the most extensive range of colors as yet pub- 
lished, together with a list of all recorded color names in use 
up to this time in the English language. This dictionary pre- 
sents more than 6000 colors, ranging from colors approaching 
white to colors approaching black through practically every 
eradation of hue, saturation and brightness. 


This book is not intended to introduce any new type of color 
system nor offer color names that have not already appeared 
in print. The language of color as recorded in this dictionary 
is, generally speaking, the expression of matured and prac- 
tised usage. The ideal has been to produce a complete work 
of reference in which may be found the name of every color, 
and a sample of it, that has ever attained record in the English 
language. , 


It further presents a table showing the frequency of use of 
the principal color names, a comparison table showing the 
principal color names in several languages, and the spectro- 
photometric measurements of various colors. 


Another interesting feature is the secondary index, which 
groups all synonymous names under a single main name. 


Just as the English Dictionary records words and their 
meanings acording to their accepted usage, this Color Diction- 
ary is arecord of color words and the particular color sensa- 
tions they identify, as established by consensus of opinion. 
The system of color arrangement employed makes it easy to 
find any named color and to readily choose an unnamed color 
for a given purpose in the textile or paint industry. 


This work is not, in any sense, an arbitrary establishment 
of new standards, but is a co-ordination of the best thought 
and work which has been published up to this time on the 
subject of color. 


Munsell System.—Mr. A. H. Munsell published in 1905 a 
book entitled ‘‘A Color Notation,’’ and later a ‘‘Color Atlas”’ 
based on the system outlined in his book. The book outlines 
the system of arranging colors according to the three attri- 
butes, Hue, Value and Chroma, and the Color Atlas contains 
color chips arranged in the order given in the system. A brief 
description of the system, which is considered to be perhaps 
the best of a number of similar systems, follows. 


220 Color Systems, Colorimeters, Etc. 
aan reer errr 


Munsell defines the words Hue, Value and Chroma as fol- 
lows: . 

Hue.—Specifically and technically, distinctive quality of 

coloring in an object or on a surface; the respect in which 


red, yellow, green, blue, etc., differ from one another; that. 


in which colors of equal luminosity and chroma may differ. 

Value.—In painting and the allied arts, relation of one 
object, part or atmospheric plane of a picture to others, 
with reference to light and shade, the idea of hue being ab- 
stracted. . ; 

Chroma.—The degree of departure of a color sensation 
from that of white or gray; the intensity of a distinctive 
hue; color intensity. : 


FIGURE 81 


Theoretically every color finds its place on a color tree tak- 
ing the shape, more or less, of a cylinder placed on its base 
(Fig. 81). A band is traced around the equator and divided 
into ten equal spaces which are lettered R, red, YR, yellow 
red; Y, yellow; GY, green yellow; G, green; BG, blue green; 
B, blue; PB, purple blue; P, purple; RP, red purple. The 
spaces between the above divisions are divided into five equal 
parts, thus making space for fifty different hues around the 
equator of the tree. 


The vertical axis of the tree is divided into 10 parts from 0 
(black) at the base to 10 (white) at the top, thus giving the 
dimension for the measurement of value. 


Color Systems, Colorimeters, Etc. 221 


The third attribute of a color, the Chroma, is shown on the 
tree by the length of radials from the center axis. ‘These ra- 
dials are divided into 10 parts, starting with 0 at the axis. 

To describe a color in the terms of Munsell’s system, the hue 
is noted as one of the ten symbols R, YR, Y, GY, G, BG, B, PB, 
P, RP. Value is shown by a small figure to the right of the 
symbol and above, while Chroma is shown by a small figure 


to the right and below, as, for example, Be The color rep- 


resented by the figure just given would be ared. The value 5 
being equidistant between 0 and 10 indicates that the color 
lies equidistant in value between black and white. The Chro- 
ma 9 indicates that the intensity of the color is very close to 
the most intense color of the hue noted. 


The Munsell Atlas—The Munsell Color Atlas consists of 15 
eharts on which are shown 882 variations of the ten principle 
hues given previously as RP, P, PB, B, BG, G, GY, Y, YR, R. 

The first chart (H) gives these principal hues across the 
page with a range of value for each one down the page. The 
second chart (V) gives the range of value between White at 
the top and Black at the bottom. The third chart (C) shows 
the range of Chroma for several hues plotted at the various 
positions on the vertical value scale. 7 


The next five charts, (R) showing red and its complement 
blue green; (Y) showing yellow and its complement purple 
blue; (G) showing green and its complement red purple; (B) 
showing blue and its complement yellow red; (P) showing 
purple and its complement yellow green; consist of Value plot- 
ted vertically and Chroma plotted horizontally. 

The last seven charts consist of plotting the Hue and the 
Chroma when the value is a constant in each case. 

Chart (20), V = 2; (30), V = 3, (40), V = 4; (50), V = 9; 
(60), V — 6; (70), V = 7; (80), V = 8. 

The number of the chart was originally planned to desig- 
nate the percentage of incident light reflected by the samples. 
The squares of the Munsell values are proportional to the re- 
flection of sunlight. 

The Ridgway System.*—Mr. Robert Ridgway published in 
1912 a color chart containing 1,115 named colors, based on the 


*Color Standards and Nomenclature. Robert Ridgway. 


Zee Color Systems, Colorimeters, Etc. 
a nt 
solar spectrum, with its six fundamental colors and intermedi- 
ate hues. He selected 36 fundamental hues, stated as the 
greatest practical number for the pictorial representation of 
the colors in their various modifications. The chart may be 
divided into six main divisions. The first division shows the 
36 fundamental hues, each with a seale of three tints and three 
shades, the percentage of white for the tints being respectively 
9.5 per cent, 22.5 per cent, and 45 per cent, while the percent- 
age of black for the shades is 45 per cent, 70.5 per cent, and 
87.5 per cent. The five remaining divisions show these same 
36 hues, together with their tints and shades, displayed in ex- 
actly the same manner as in the first division, the difference 
being that all the colors in these last five divisions are dulled 
by the admixture of a neutral gray. The amounts of neutral 
gray are, for the divisions following in order, 32 per cent, 58 
per cent, 77 per cent, 90 per cent, and 95.5 per cent respec- 
tively. 

Each of the colors shown has been given a name and also a 
number. These numbers are arranged in the following man- 
ner: In the first division the 36 fundamental hues are num- 
bered 1, 3, 5, 7, etc., up to 71, intervals being left so that colors 
which do not appear on the chart may be given a number. 
Instead of stating that a color lies between 3 and 5, for exam- 
ple, it would be given the number 4. The tints are lettered 
b, d, and f, and the shades i,k, and m, intervals again being 
left for tints or shades intermediate between those on the chart. 
In the following divisions the notation is exactly the same as 
in the first division, with the exception that for the second 
division a is placed after the number of the color; for the 
third ”, fourth ’, and for the fifth ’””. To illustrate the method 
of numbering, take, for example, the color given the notation 
66” e. This would be found in the third division of the chart, 
therefore having 58 per cent of neutral gray added to the cor- 
responding color of the first division. | 

It would be an intermediate hue between the two marked 
65” and 67”. 

It would be an intermediate tint between the marked d and 
the one marked f. 

Wilkinson’s Color-Sound System.—Charles Henry Wilkin- 
son published a color chart in 1891, in which a comparison is 
drawn between the variations in color and the variations in: 


Color Systems, Colorimeters, Etc. 223 


sound. The colors of the prism, Red, Orange, Yellow, Green, 
Blue, Indigo, and Violet, are given the musical notations C, 
D, E. F, G, A, B, respectively. This number is increased to 12, 
as in the musical scale, by the addition of sharps and flats, 
making the complete color octave the same as the musical oc- 
tave. 


The system is divided into 19 octaves graduated from 1 
which contains 1 part black to 7 parts of color, through 9 
which contains only the pure color with no admixture of black 
or white, to 19 which contains 255 parts white to 1 part pure 
eolor. 


The above outlined system is maintained throughout the 
following 24 charts of ‘‘Ranges.’’ Each range is made up of 
three colors placed together in a chord, for example: Range 1, 
C, Kh», G; Range 2, C, E, G; Range 3, Ct, E, G#, ete. 

Twenty-four different combinations, varying from white 
to black in 19 octaves, compose each range; for example, Range 
1, composed of the three colors C, EH’, G, is subdivided into 24 
combinations of the colors, C, E® and G, such as C, CG, CGC, 
CH°GC, ete. Each of these combinations is followed through 
19 octaves from black to white. 


Wilkinson’s system contains over 10,500 color chips, some 
of which are duplications of the same colors. These chips are 
arranged in an order which necessitates looking practically 
through the entire system for a match. The fact that the col- 
ors of the prism are given unfamiliar names only adds to the 
confusion begun by the unwieldy number of colors dealt with. 
No attempt was made to match samples against this system, 
but it is thought that probably, due to the large number of 
colors, a few more samples may be matched. The general 
criticisms of color charts apply to Wilkinson’s system. 


Societe Francaise des Chrysanthemistes Repertoire de Cou- 
leurs.—The French Chrysanthemum Society a number of years 
ago published a color chart called the ‘‘Repertoire de Cou- 
leurs,’’ designed by Dauthenay and several others. This chart 
consists of approximately 1,400 colors arranged in twelve se- 
ries as follows: 1, Whites and tinted whites; 2, Yellows; 3, 
Oranges; 4, Reds; 5, Roses; 6, Purples; 7, Violets; 8, Blues; 9, 
Greens; 10, Browns and Ochres; 11, Maroons; and 12, Blacks 


224 Color Systems, Colorimeters, Etc. 


and Grays. Each series contains a varying number of plates 
and each plate shows four variations of the same hue. 


This chart is simply a display of various colors without any 
definite order, except the division into series. It is apparently 
specialized for the purpose for which it is intended, that of 
defining the colors of flowers and plants, as there are great 
numbers of greens, browns, reds, and roses. A number of 
plates show the colors of copper, bronze, silver, and gold which 
are not usually shown in such charts. 


Chevreul’s Color Chart.*—Michel Eugene Chevreul devised 
a color chart containing ten chromatic circles. Hach circle is 
composed of 72 colors arranged in the order Red, Red Orange, 
Orange, Orange Yellow, Yellow, Yellow Green, Green, Green 
Blue, Blue, Blue Violet, Violet, Violet Red. The first circle 
or chart contains what are onlied the purest and most intense 
colors, and each of the succeeding circles or charts contains 
these same colors to which has been added an ever-increasing 
definite amount of black. 


Following these are other charts arranged in bands each 
composed of 22 steps ranging from 0 White, through the vari- 
ous changes in one of the 72 original colors, to 21 Black. The 
color of the original color circle in each ease is placed at 10. 


Charts of Moses Harris.—In 1811, nearly thirty years after 
the death of Moses Harris, were published two charts of colors 
based on his theories. These charts represent one of the earli- 
est, if not the first, attempt at showing an arrangement of a 
oe number of colors. 


The first plate, known as the Prismatic Chaee contains 18 
colors occurring in the spectrum, arranged ina circle. ‘These 
18 colors are based on the ‘‘three grand primitive colors, Red, 
Blue, and Yellow, and are placed in the following order around 
the circle: Red, Orange Red, Red Orange, Orange, Yellow Or- 
ange, Orange Yellow, Yellow, Green Yellow, Yellow Green, 
Green, Blue Green, Green Blue, Blue, Purple Blue, Blue Pur- 
ple, Purple, Red Purple, Purple Red. The whole circle is di- 
vided into 20 concentric circles or ‘‘degrees of power,’’ vary- 
ing from 20, the deepest and strongest color at the inside, to 0, 
the weakest at the outside. 


* An early attempt and of little practical use at the present time. 


Color Systems, Colorimeters, Etc. VA) 


The arrangement of the second and last plate or ‘‘Compound 
Chart’’ is exactly the same as in the Prismatic Chart, the dif- 
ference being that it is based on the three mediate colors, Or- 
ange, Green, and Purple. The 18 colors in this case are placed 
around the circle in the following order: Orange, Olive Orange, 
Orange Olive, Olive, Green Olive, Olive Green, Green, Slate 
Green, Green Slate, Slate, Purple Slate, Slate Purple, Purple, 
Brown Purple, Purple Brown, Brown, Orange Brown, Brown 
Orange. 

Harris stated that another chart might be made based on 
Olive, Slate, and Brown, but that any further division would 
give colors between which there could be little differentiation. 


These charts are of no practical use at the present time, but 
are an example of the first attempts to display an orderly ar- 
rangement of colors. 


In diseussing color charts, the main objection that can be 
found with the majority is the fact that they do not contain a 
sufficient number of colors to enable a large number of samples 
to be matched. 


The colors used in the manufacture of these charts are as 
fast as it is possible to make them, but in a number of cases 
the pigments used in painting the chips are sensitive to pro- 
longed exposure to light. It is probable that these charts 
change slightly in some particulars over a period of a few 
years. 

In making such a large number of colors as are used in the 
charts, slight errors creep in, due to a variation in the pig- 
ments, ete., used. Unless all the colors used are tested with 
great care, no two charts will be exactly alike in every particu- 
lar. 

With regard to the use of these charts, several factors are 
of importance: | 

In specifying a color on a certain chart, the character of 
illumination must also be stated in understandable terms. 
Colors appear very differently under different sources of illu- 
mination. What would seem to be a match under a certain 
illumination might be considerably off under another light of 
slightly different wave length. 


When a color is being matched, it must not be influenced 
by other colors. Colors when placed in juxtaposition to 


226 Color Systems, Colorimeters, Etc. 


other colors are often so influenced as to assume an entirely 
different appearance. 

The majority of color charts are in flat colors, which in- 
creases the difficulty of matching glossy paint chips with them. 
It is necessary that both the sample and chart shall present 
the same type of surface to the eye, in order that a perfect 
match be made. ‘This can easily be observed by comparing the 
shiny and the flat surfaces of a piece of silk. 

It will be seen from the above that a color cannot be defin- 
itely specified by giving it a reference number on a certain 
color chart, unless the same chart is used by the same operator 
and at the same illumination each time. Colors lying between 
two colors on the chart will be assigned to different positions 
by various operators. In the 4th, 5th, and 6th divisions of 
the Ridgway system, for example, several numbers for inter- 
mediate colors are left blank between two adjacent colors. In 
this case different operators would assign widely different 
numbers to colors not appearing on the chart. 

Observers who are color blind, or partially so, believe that 
they can match samples against the charts, but the results ob- 
tained by them are incorrect. 


(‘OLORIMETERS 


Numerous types of colorimeters have been devised for the 
measurement of color with optical aid. Colorimeters define 
the sensation which the color produces on the eye and see only 
that which the eye sees—that is, when two sample colors ap- 
pear the same under one illumination they will appear to be 
same in the colorimeter. But if these same two samples should 
appear to be different under another illumination then they 
will appear to be different to the colorimeter, if the latter il- 
lumination is used. In other words, the fact that they appear 
alike to the colorimeter is not conclusive proof that they will 
appear alike under all conditions. Two colors may match ex- 
actly in the instrument under white light and yet be entirely 
different under common electric-light illumination. 


Colorimeters have the advantage that results may be rapidly 
obtained by their use. A measurement consists solely of set- 
ting three or four calibrated adjustments. In order to repro- 
duce the color found at any future time, it is only necessary 
to set the instrument in the same manner as before. In other 


Color Systems, Colorimeters, Etc. 227 


words, if a standard color be measured on the instrument, the 
same setting can be made at a future time and samples com- 
pared with this setting, thus providing an unchanging ref- 
erence standard. 

Results agreeing very closely (within the range of the in- 
strument) may be obtained by persons having normal vision, 
but since the operation of colorimeters depends entirely upon 
the judgment of a match by a particular observer, color blind 
or even partially color blind persons are unable to take read- 
ings. 

Colorimeters may be subdivided under two headings. The 
monochromatic type, of which the Nutting Colorimeter is an 
example, and the trichromatic, of which the Jones, Ives, Baw- 
tree, Lovibond, Guild, ete., are examples. 


The Monochromatic Colorimeter.—Defines the color under 
examination in terms of dominant hue and per cent of white 
hight. Dominant hue is given in terms of wave length. The 
visible spectrum may be divided in a number of parts from 
wave length 440 to wave length 700. The dominant hue of a 
color is the wave length of the spectrum color which most 
nearly approaches the sample under examination. 


The Trichromatic Colorimeter.—Defines a color in terms of 
three arbitrary primaries, Red, Green, and Blue. These pri- 
maries vary with the different types of instruments. The 
colors are provided by dyed gelatine wedges, transparent glass 
filters, ete. This class may be further subdivided into two 
main types: those which operate on the Additive Principle 
and those which operate on the Subtractive Principle. 


Additive Principle-—Three arbitrary primaries are taken, 
Red, Green, and Blue, with a device for varying the intensity 
of each. The color of the sample is reproduced by varying 
these intensities. 


Subtractive Principle——The light passes through variable 
color filters, subtracting a greater or less amount of a particu- 
lar color. It is not possible to introduce variations of hue by 
changing the aperture as in additive instruments. This vari- 
ation in hue is obtained by changing the thickness of colored 
filters. 


When a trichromatic colorimeter is employed for analysis 
or synthesis, the color sensation in terms of true red, true 


228 Color Systems, Colorimeters, Ete. 


green, and true blue components depends entirely upon an 
accurate knowledge of the sensation values of the three filters 
used in the instrument. When these sensation values are 
known, the results obtained by the instrument may be trans- 
posed by calculation into true value. Further, when these 
true values are known, it is then possible to determine by an- 
other series of calculations the hue, saturation, and brilliance 
of a sample. 


The Nutting Colorimeter.*—The Nutting Colorimeter is a 
monochromatic analyzer which has wide range and 1s of high 
precision. A monochromatic analyzer is an instrument which 
defines a color in terms of the dominant hue or wave length of 
the color and the percentage of white light. 


The instrument consists of a spectral collimator to admit 
light to be spread into a spectrum by a constant deviation type 
dispersing prism. This prism 1s rotated by a fine screw at- 
tached to a drum on which the wave length of the light re- 
flected by the sample may be read directly when a match has 
been obtained. The intensity of the portion of the spectrum 
under examination may be varied by rotating one of the polar-— 
izing prisms interposed in the path of the light. 


Two more collimators, one to admit the standard white light 
and the other to admit the light from the sample, are placed 
so that the light from the former strikes a mirror wheel con- 
sisting of two quarters plain glass and two quarters mirror, 
and the light from the latter strikes a prism which acts as a 
mirror, simply changing the direction. Both these eollimat- 
ors are fitted with polarizing prisms for varying the intensity 
of the light admitted. The whole is so arranged that all three 
paths of light converge in the eyepiece. The mirror wheel re- 
ferred to above is stationary in a clear glass position when the 
color match is being made, but is rotated as a flicker photo- 
meter when the intensity is matched. 


The sensitiveness of the instrument is that of the observer’s 
eye. The uncertainty in the wave length of the dominant hue 
is about 1 or 2 millimicrons, except in the extreme red and vio- 
let, and for colors very near neutral gray and for very dark 
colors. 


The instrument is a very expensive one. 


* Bull. Bureau of Standards, Vol. 9, No. 1. 


Color Systems, Colorimeters, Etc. 229 


The process and calculations are more complex than in some 
of the more modern instruments. 


Bawtree Colorimeter.*—This instrument, which was recently 
designed by a member of the British Oil and Colour Chem- 
ists’ Association, consists of two light-diffusing systems which 
share equally the illumination from the source of hight em- 
ployed, preferably a metal filament electric lamp. In one sys- 
tem is placed a shutter operated by a pointer and scale divided 
into 100 parts. In the other system are three shutters of the 
same kind, covering sheets of transparent medium of accur- 
ately standardized primary color of such strengths that the 
three when each shutter is opened an equal amount, will pro- 
duce white light. When the three color shutters are fully open, 
the white light matches that from the other.side, when its one 
shutter stands at 10. The light issues on the two sides from 
- openings two inches square, separated only by the thickness 
of a piece of tin. Now, if a magenta painted card be placed 
behind the white opening and a piece of standardized white 
material provided be placed behind the opening correspond- 
ing to the color slides, it may be found, for example, that to 
match it the scales read: Red, 100; Green, 10; Blue, 60. This 
tells at once the actual percentages of colored light which the 
material reflects, and also shows that apart from its color it 
reflects 10 per cent of white light. 


Lovibond Tintometer.—In 1886 Mr. J. W. Lovibond made 
public the results of his research on color measurement. From 
that time until 1920, when the finally approved tintometer ap- 
peared on the market, many changes were made. Usually the 
Lovibond tintometer, for use by the paint trade, is associated 
with color readings on liquids such as varnishes, oils, etc., but 
by the use of attachments furnished by the manufacturers col- 
ored opaque surfaces may be measured. 


The instrument consists of a viewing box with no optical ar- 
rangements whatsoever. In one side is placed the sample to 
be tested, and in the other are placed standardized colored 
glasses until a color match has been obtained. 

A complete set of color glasses or standards consists of 155 
glasses for each of three scales or colors, Crimson, Yellow- 


* Jour. Oil and Colour Chemists’ Assn., No. 11, 1919, pp. 68-70. Description 
and criticism of Bawtree Colorimeter complete. 


230 Color Systems, Colorimeters, Etc. 


Green, and Blue, making a total of 465 glasses. Hach scale 
consists of glass slides all of the same color but varying in 
thickness in definite steps from .01 to 20.0 tint units. These 
steps are so arranged that three glasses are all that are re- 
quired to obtain any setting for one color. Sufficient glasses 
of all three colors are inserted to match the sample. All the 
glasses used in making a match must be noted together with 
their colors. If four glasses of one color totaling a certain 
number of tint units are used, the resultant color will be darker 
than if three glasses totaling the same number of tints are 
used. 


A complete set of glasses are expensive. They are easily 
broken. 


Hach individual glass must be noted, as a different combina- 
tion of glasses will give a different result. 

Notr.—A Circular on the Accuracy of the Lovibond Set at the U. 8. Bureau 
of Standards has recently been published by the Bureau. 

The sample is difficult to compare with the glasses, as there 
are no optical arrangements for viewing both, side by side. 


Ives Color Meter.*—In 1907, Frederic E. Ives perfected a 
‘‘Color Meter’’ based on the same principles as Clerk Max- 
well’s Color Box. This color meter compares the light from 
a sample with the light coming from an adjustable mixture of 
the three primaries, Red, Green, and Blue-Violet. The instru- 
ment itself is divided in two halves, and white light or the 
light from the sample to be measured is admitted through the 
right half passing to the right half of the eyepiece. The light 
on the left half comes from three lateral slits, Red, Green, and 
Blue-Violet, and passes through a diffraction grating, in place 
of prisms in Maxwell’s box, which converges all three beams 
of light in the left half of the eyepiece. A color match in both 
halves of the field is obtained by adjusting these slits by means 
of a micrometer screw calibrated from 0 to 100. The position 
of each slit shown by a pointer is noted and the color is defined, 
as, Red, 40; Green, 20; Blue-Violet, 60, for example. 


The percentage of black may be found by subtracting the 
largest reading obtained from 100, and also the percentage of 
white is represented by the smallest reading obtained, for ex- 
ample above, Black = 100— 60 = 40, White = 20. 


* Journal Franklin Institute, Vol. 164, 1907, p. 47. 


Color Systems, Colorimeters, Etc. 231 


The instrument must be pointed at a white object or must be 
illuminated by white light, otherwise comparisons would not 
be true under differing illumination. In order to use the in- 
strument persons must have normal vision. 


The Hess-Ives Tint Photometer.—The underlying principle 
of the Hess-Ives Tint Photometer is somewhat similar to the 
spectrophotometer. The sample to be matched is compared 
with a block of magnesium carbonate, which is assumed at the 
present time to be the whitest known substance. The illumina- 
tion is furnished by a daylight electric bulb. The light from 
this source is reflected from the sample to be tested and from 
the block of magnesium carbonate, which are placed side by 
side on a stand, into the instrument by a mirror. The instru- 
ment is so arranged that the light reflected from the magne- 
sium carbonate block illuminates one-half of the field, while the 
light reflected from the sample illuminates the other. A mix- 
ing wheel revolves in the path of the light, insuring the even 
distribution of light over both halves of the field, which is di- 
vided vertically instead of horizontally, as is usually the cus- 
tom. When the instrument is in use, a calibrated screw must 
be adjusted until both halves of the field are illuminated 
equally. | 

After these adjustments have been made, a red color screen 
is put in position. A shutter, operated by a calibrated lever, 
regulates the light transmitted to the eyepiece by the mag- 
nesium carbonate block. This lever is now moved back and 
forth until a match in both halves of the field has been ob- 
tained. 


When the match is obtained, the position of this lever is 
noted, as, for example, Red, 60. The same procedure is then 
followed with a Green and with a Blue-Violet screen. The 
full notation is then made, for example, as, Red, 60; Green, 80; 
Blue-Violet, 30, the sample being a green containing some red, 
and considerably less blue-violet. If all these three figures 
were proportionately lowered, the sample would have a pro- 
portionately increased admixture of black, and therefore would 
be darker. These results may be shown graphically on cross- 
section paper. The points are plotted on three vertical lines 
marked Red, Green, and Blue-Violet, divided into 100 parts 
with 0 at the bottom and 100 at the top. Very little study 


232 Color Systems, Colorimeters, Etc. 
SN aaa 
enables one to more or less picture a color by a reference to 
this graphic representation. 

The results given by this instrument on one sample (pea 
ereen) are shown on page 249. These results have been plot- 
ted as a three-point curve. 


From the results obtained on the instrument the luminosity 
value and also the admixture of black may be calculated. <A 
luminosity factor has been determined for each of the three 
colors. These are, Red, 0.19; Green, 0.71; and Blue-Violet, 
0.10. To calculate the luminosity, the red reading of the sam- 
ple is multiplied by the red factor, the green by the green fac- 
tor, and the blue-violet by the blue-violet factor. These three 
derived values are then added and the results are the total 
luminosity. Perfect luminosity is 100 per cent, consequently 
the admixture of black is the difference between the total In- 
minosity and 100 per cent. 


Comments on Hess-Ives Tint Photometer.—The results 
which the writers have obtained on the Hess-Ives Tint Photo- 
meter indicate that the instrument will differentiate between 
two colors which are very similar in appearance to the naked 
eye. This will be seen by reference to the charts of colors 1, 
4 and 5 and also 2 and 3. These colors are different to the 
eye and the instrument points out that difference. 


It is felt that there is a possibility of finding at some time 
two colors, which are entirely different to the naked eye, such 
as ared and a green, and yet give the same results when meas- 
ured. However, this possibility seems rather remote. 


A comparison of the performance of two Hess-Ives Tint Pho- 
tometers cannot be given at this time due to the lack of suffi- 
cient data. The manufacturers state, however, that two in- 
struments agree very closely. This agreement depends upon 
the exact duplication of the colored glass filters and also the 
block of magnesium carbonate. 


The instrument appears to be rather flimsily constructed 
and might not stand up under hard usage. This, however, 
is a difficulty which could be easily remedied. , 

The Eastman Universal Colorimeter.*—The Hastman Uni- 
versal Colorimeter was designed recently by Mr. Loyd A. 


*Jour. Optical Soc. Am., 4; 420 (1920). 


Bees ger 0S ab diet 


ey eS 


Color Systems, Colorimeters, Etc. 233 
Jones, of the Fastman Kodak Co. During the World War 
it was used to a large extent in determining the color of the 
horizon and of the sea under various conditions. These results 
were then used in the tinting and shading of camouflage paints 
to be used on vessels, ete. 


The instrument has numerous attachments each for a par- 
ticular use, such as the measurement of the color of liquids, 
dyed gelatines and glasses, another for reflecting surfaces, 
another for light-colored liquids, ete. 


“The colorimeter* operates on the subtractive principle, 
and any desired color is obtained in the comparison field by 


FIGURE 82 


THE EASTMAN UNIVERSAL COLORIMETER. 


the subtraction of certain parts from the white light used for 
the illumination of the comparison field. This subtraction 
is accomplished by the use of dyed gelatine wedges. These 
wedges are made by coating glass plates with dyed gelatine, 
so that the thickness of the gelatine layer varies from zero 
at one end to a maximum at the other. The three color addi- 
tive primaries are red, green, and blue, and when light of these 
three colors is combined white light is obtained. By using 
three wedges, each of which absorbs one of the three additive 


* Instructions for operating the Eastman Universal Colorimeter. 


234 Color Systems, Colorimeters, Etc. 


primaries, any desired amount of each primary may be sub- 
tracted from the white light. 


The method of obtaining any desired color by the subtrac- 
tive method may be explained by reference to Fig. 83. The 
three squares in the top line of the diagram represent red, 
green, and blue components of white light. Now, if by some 
means the blue component is absorbed, we have left the red 
and green components which yield yellow. That is, if the blue 
component be removed from white light the remaining hight 
will appear yellow, or, in the terminology of the subtractive 
method, minus blue. Likewise, as indicated in the third line 
of the diagram, if green is absorbed, the blue and red com- 
ponents remain, giving magenta or minus green. While if 
the red component be absorbed, as indicated in the fourth 
line of the diagram, the blue and green components remain, 
giving a blue green or minus red. This illustrates the nature 
of the three color subtractive primaries, namely, minus blue, 
minus green, and minus red. 


Blue Green Red 
(Removed ) Green Red 24 
(—Blue) Yellow 
Blue (Removed) Red (—Green) Magenta 
Blue Green (Removed) (—Red) Blue-Green 


FIGURE 83 


The action of the (—Blue) wedge in the colorimeter is, 
therefore, illustrated by the second line of the diagram in 
Fig. 83. When this wedge is set at zero, that is, completely 
withdrawn from the path of light illuminating the compari- 
son field, no absorption takes place, but as it is introduced into 
the path of the light, blue light is subtracted from the white 
light to a greater and greater extent as the thickness of the 
gelatine coating increases. When this wedge is introduced 
so that the point of maximum thickness is in the path of the 
white light, a condition similar to that indicated in the second 
line of the diagram exists, and practically all of the blue light 
present in the white light of the comparison field is absorbed, 
leaving the comparison field illuminated by (—Blue) or yel- 
low light. The conditions existing when the (—Green) and 


Color Systems, Colorimeters, Etc. 235 


(—Red) wedges are inserted are shown in the third and fourth 
lines of the diagram. 


Blue Removed Green Removed Red 
Blue Green Removed Red Removed 
Blue Removed Green Red Removed 
FIGURE 84 


It is evident that (Fig. 84) if the (—Blue) and (—Green) be 
inserted simultaneously, the transmitted light will be red, 
while if the (—Green) and (—Red) are used together, blue 
will be obtained, and as a third combination if the (—Blue) 
and (—Red) be used together green light only will be trans- 
mitted. ’’ 


The readings which are given in the tables and from which 
the curves are drawn are reported in terms of —Green, 
—Blue, and —Red. It will be seen that if the sample is Green, 
no green should be subtracted, therefore the —Green wedge 
should remain in the zero position and the reading in this 
column will be zero. When the sample is blue, the —Blue 
wedge is placed at zero and the reading is zero, and when the 
sample is red the —Red wedge is at zero and the reading is 
zero. In the case of colors which do not come under the head- 
ing of red, green or blue, one of the three wedges must remain 
at zero, which is determined by one of the component colors 
which go to make up the color of the sample. For example, 
in the case of some brown samples the —Red wedge remains 
at zero and the reading in the —Red column is zero. 


The readings in the column marked Neutral represent the 
amount of neutral gray which it is necessary to add to match 
the intensity of the sample. 


The operation of the colorimeter is simple. 


The electric current furnished by a 3 cell 100 ampere-hour 
storage battery is first properly adjusted, giving the correct 
illumination which is obtained by checking against a standard 
illumination furnished with the machine. After the lamps 
have been lighted, the field presented to the eye is a circle 
divided in half by a horizontal line. The lower half of the 
field represents the color reflected from the sample and the 


236 Color Systems, Colorimeters, Etc. 


upper half is the color produced by introducing the various 
wedges. In order to take a reading, it 1s necessary to intro- 
duce the two color wedges decided upon, until a color mateh 


EastMAN UNIVERSAL COLORIMETER 
PoLAR CoO-ORDINATE CHART 


FIGuRE 85 


The color is denoted by the point on the vector in each case. The points 


plotted by the writers are based on the results of the Eastman Kodak Co. 
at their laboratory. 


is obtained in the upper and lower halves of the circle. The 
intensity is controlled meanwhile with the neutral wedge. 
When a good match has been obtained both in color and in- 
tensity, the position of all the wedges is recorded. Several 


te tS 


Color Systems, Colorimeters, Etc. Dal 


readings are made and an average taken, as sufficient accuracy 
cannot be obtained with one setting. 


Representation of the Results of the Eastman Colorimeter. 
—The readings obtained on the Kastman Universal Colori- 
meter on one sample of (pea green) are graphically shown in 
the form of a curve on page 249. This has been done solely 
for the purpose of comparing more easily the results obtained 
by two observers on two different instruments. 


Correspondence with Mr. L. A. Jones, of the Hastman 
Kodak Company, has brought out the fact that the results 
obtained on the instrument may be calculated to arbitrary hue 
and saturation factors which can be presented on a polar co- 
ordinate chart. The three subtractive primaries, green, blue, 
and red, are placed at 0°, 120°, and 240° respectively, while 
the three additive primaries, red, green, and blue, are placed 
at 60°, 180°, and 300° respectively. 


The position of a point is represented by two values; X, 
the length of the vector, that is, the line drawn from the center 
to the point in question; and ®, the angle between this vector 
and the reference axis of the system, that is, the line from 
the center of the circle to zero position on the circumference. 
A variation in ® may be considered as equivalent to a variation 
in hue, while a variation in X designates a variation in the 
saturation factor. Since color requires a statement of three 
factors for its complete specification, it is obviously impos- 
sible in any single plan having but two dimensions to plot 
graphically all three of these variable. A single plane dia- 
eram such as this, therefore, is only adequate for the show- 
ing of variations in the two factors, hue and saturation. The 
method used for plotting the colorimeter readings in this co- 
ordinate system is as follows: 


Let G = the scale reading of minus green wedges. 
Let B = the scale reading of minus blue wedges. 
Let R = the scale reading of minus red wedges. 
Let N = the scale reading of neutral wedges. 


Since any color can be matched by the use of two of the colored 
wedges in combination with the neutral, we have three differ- 


238 Color Systems, Colorimeters, Etc. 


ent equations for finding the value of ® from the seale read- 
ings. They are as follows: 
When the minus green and minus blue wedges are used 


pass B 20 
® Ge Make 
When the minus blue and red wedges are used 
R 
a eee ye . 
=H X 120 + 120 | 
When the minus green and minus red wedges are used 


The values of ® computed according to these equations will 
locate the hue of any sample, and a line drawn through the 
center to the designated angle will be the locus of the point 
which must be plotted to represent the hue and saturation 


of the sample in the polar co-ordinate diagram. 

The value of X is determined by taking the average of the 
two colored wedge readings, thus, when the minus green and 
minus blue wedges are used: 


@-EB 
Die: a2 
and likewise for the other combination 
ue aa 
X=——9 
or 
G+R 
nee =e 


This will now locate the point which gives a definite idea as to 
the hue and saturation of the color in question. 


There is no definite relation between the angular values and 
the wave lengths of the dominant hue. It should be empha- 
sized that this system is not a method of converting the colori- 
meter readings to the standard notation of the monochromatic 
system. | 


On pages 248 and 249 are shown specimen graphs on the 
same green which have been plotted from readings on three 
different instruments, according to this method in Fig. 85. 


Comments on Eastman Universal Colorvmeter.—In discuss- 
ing the Eastman Universal Colorimeter, one distinct advan- 
tage over a spectrophotometer may be noted, namely, the 
duplication of a standard color in the instrument at a future 
time by making the corresponding setting of the wedges. It 


Color Systems, Colorimeters, Etc. 239 
ee ..............__ 
would be thought that once a standard color has been measured 
on the instrument and the results recorded, any sample may 
be compared with this standard by setting the instrument to 
the recorded values of the standard. However, one difficulty 
arises in this connection, for while it is theoretically true, it 
fails to a slight extent in practice. The sample may be slightly 
different from the standard to the naked eye and yet give 
results on the instrument which are well within the limits of 
experimental error. A comparison of the reading on Greens 
#4 and #5 show this fact quite clearly. ‘The two colors are 
quite different to the eye and yet the four lines in the graphic 
representation of these two colors are noticeably interlaced, 
showing that the results of one, due to experimental error or 
to the slight difference in two instruments, might easily be 
mistaken for the results of the other. 


With a little practice colors may be matched quite readily 
in the instrument. The manufacturers state that an exact 
match cannot be made and that an average of several readings 
must be taken. This is due, in a large measure, to eye fatigue. 
When the colors in the instrument are observed for a short 
time, the eye retains the color shown and does not react quickly 
to the slight changes which are necessary in matching the 
sample. This is particularly noticeable after using the instru- 
ment for several hours, and for this reason it is thought that 
the instrument should not be used uninterruptedly when a 
large number of samples are to be measured. Results obtained 
on the instrument by partially or totally color-blind persons 
will not agree with those obtained by persons having normal 
vision. Results depend entirely upon the observer’s judg- 
ment of a color match. 


Martin and Gamble* state that ‘‘several questions naturally 
arise (with regard to a Wedge Colorimeter) connected with 
the permanence and the possibility of producing wedges 
identical in performance for similar instruments, for unless 
various instruments will give identical arbitrary indications 
of the same color the special calculations necessary to in- 
terpret a measurement for any one instrument will certainly 
inhibit its commercial use.’’ 


The manufacturers state that the wedges used in the instru- 
ment have been found to be constant as regards a change in 


*Color and Methods of Color Reproduction. Martin & Gamble, p. 113. 


240 Color Systems, Colorimeters, Etc. 
OS 
eolor from the standard over a considerable period of time. 
They report that one wedge which was exposed to direct sun- 
light for over a month showed no appreciable change. 

In comparing the check results of two instruments, it has 
been observed that while certain portions of two blue wedges, 
for example, will give absolute agreement, other portions of 
the same two wedges will give slightly different results. 
Slightly differing values will be obtained at the points where 
the wedges differ slightly. No data is obtainable at present 
which will show the maximum difference at a definite point in 
a number of wedges of a certain color. It is thought that the 
experimental error noted previously is due largely to this 
difference in wedges at various fixed points. 


Howland Comparative Color Photometer.*—The Howland 
Comparative Color Photometer is basically a modern adapta- 
tion of Maxwell’s principle of spinning dises. Mr. Howland 
describes the Photometer as ‘‘a light, tight box with a slide 
in the front having a small opening, through the aperture of 


ea 


1 


Ay D> 


which the operator sees the absolute black of the interior. It 
contains a small high-speed motor with a shaft arranged for 
clamping dises of thin cardboard which may be spun close 
behind the opening. The motor is screened from view by a 
second partition covered with black velvet, while a third screen 
back of the motor aids in absorbing any light rays which might 
otherwise find their way to the black velvet which covers the 
back of the box on the inside.’’ By this method the back- 


FIGURE 86 


*Drugs, Oils and Paints, 32: 48 (1916) ; 33: 4384 (1918). 


Color Systems, Colorimeters, Etc. 241 


eround is so completely screened that the effect on looking ae 
the opening is one of absolute black. 


The dises with which the sample is compared are cut as is 
shown in Fig. 86. These are furnished in several colors as well 
as white and are of all sizes from 0 to 100. The black is sup- 
plied by the black of the interior of the box, showing between 
the wedges as they revolve. The sample is then put on a small 
dise over the standard ones and the whole revolved. When 
the correct percentages of the standards have been chosen so 
that the field appears uniform throughout, an equation is 
drawn: 


.Y 


Ts 


FIGURE 87 


Color of sample = Various percentages of standards used 
+ (100 — total percentages) or black. 

It has been determined that a sample is matched by 23 per 
cent Red, 20 per cent Yellow, and 19 per cent White. There- 
fore, Color of Sample = 23 per cent Red + 20 per cent Yellow 
= os 19 per cent White + 


100 — (23 + 20 + 19) or + 38 Black 


242 Color Systems, Colorimeters, Etc. 


The hue, strength, and luminosity are then calculated. 


The hue is calculated by reducing the colored areas to per- 
centage: 
234202 48 
23 = 43 = .53 or 53, Red 
20 + 43 = 47 or 47 Yellow 
The strength is calculated by adding the colored areas 
together : 
23 + 20 = 48 
The luminosity is caleulated by multiplying the colored 
areas respectively by luminosity factors stated as: 
Red, .27; Yellow, .85; Green, .25; Blue, .5 and adding the 
white area. 


98 OT See 
20 X 85 = 17.00 
White 19 


Luminosity = 42.2 
The color of the sample is now plotted on the diagram 
(Fig. 87). A line is drawn from N at the center of the diagram 
to a point on the R-Y line, 47 spaces from R and 93 spaces 
from Y. Assuming that the point N is zero on the drawn in 
line and its intersection with the R-Y line 100, the luminosity 


42 ig now marked. This point indicates the color of the 


sample. 
SPECTROPHOTOMETERS 


A spectrophotometer is an instrument by means of which a 
colored sample may be compared with a block of Magnesium 
Carbonate, which is assumed as the standard white. The 
spectral reflection curve is plotted from the results, which 
are given in percentage brilliance for all wave lengths through- 
out the visible spectrum. 


Previously in this paper the statement was made that colori- 
meters define the sensation produced on the eye by a color. A 
spectrophotometer defines the stimulus which incites that sen- 
sation. If we take a color, which to our eyes gives the sensa- 
tion of red, the colorimeter will define the red which we see 
and nothing more. However, if we take this same red and ex- 
amine it with a spectrophotometer we will obtain a series of 
values, representing the various stimuli, which when com- 
bined will produce the same red sensation as before. Itis due 
to this fact that two colors having identical spectrophoto- 


metric readings will be one and the same under all conditions — 


wee 


Color Systems, Colorimeters, Etc. 243 


of illumination. Ives* states that ‘‘the only unique specifica- 
tion of a color is by means of its spectrophotometric analysis.’’ 

Ives continues in the same article that ‘‘the objections to 
the spectrophotometer for practical color measurements are 
obvious. It is an expensive and delicate instrument. A large 
number of measurements are necessary to specify a single 
eolor. The color cannot be reproduced for study or compari- 
son by setting the instrument to the measured values. The 
results, plots of readings against wave lengths, mean little 
except to a specially trained expert. On the other hand, there 
is no ground for believing that satisfactory color measure- 
ment will ever be done by anything except high-grade and 
hence expensive apparatus or that really accurate color speci- 
fications can be made simple.’’ 

Color is produced by the vibration of a ray of light. This 
vibration has been measured and the result has been termed 
the wave length of a color. As this wave length is exceedingly 
small, a very small unit of length must be chosen. The mill- 
micron, mu, or one-millionth of a millimeter, has been chosen 
as this unit. The micron, “, sometimes used, is one-thou- 
sandth of a millimeter. It will be noticed that on the charts 
of the spectrophotometer readings of the sixteen colors else- 
where in this paper that certain wave lengths have been 
marked Red, Orange, Yellow, Green, and Blue. Abney states 
that the ranges of the wave length of certain colors are as 
follows: 


Colors Wave Lengths in Millimicrons 
Mamamarine Glue .......... from 446 to 464 
Me, ee ee 464 500 
Seeireen..s..........--- 500 AD BY ©. 
a 513 578 
eae 578 592 
ee es 592 620 ; 
eer 620 end or about 720 


Theoretically a pure spectral color has only one wave length, 
and the above figures represent all the spectral colors which 
fall under the heading of Blue, Green, Yellow, ete. 

The spectrophotometer may be set on any one of these wave 
lengths and the percentage brilliance in comparison with the 
block of Magnesium Carbonate read. <A series of readings at 


* Jour. Optical Soc. Am., 5: 469 (1921). 


244 Color Systems, Colorimeters, Etc. 


various wave lengths are taken and a curve plotted as on page 
248. These curves are commonly called spectral reflection 
curves. 

Mees* states that ‘‘the quantitative measurement of color 
is undertaken by means of an instrument termed the spectro- 
photometer, which is essentially a spectroscope with photo- 
metric attachments. In this instrument any portion of the 
spectrum can be isolated and divided into two portions having 
the same color and adjacent to one another. Into one of the 
beams is introduced the colored object to be measured, which 
produced an absorption of the spectral region in question. 
The other beam is.then darkened by some photometric means 
until the two patches, as seen through the eyepiece of the 
instrument, appear of equal intensity. Since the amount of 
darkening which has been introduced photometrically is known 
and is equal to the amount which has been caused by the ab- 
sorption of the colored object, we can read from the instru- 
ment the quantitative value of the absorption at any point of 
the spectrum. This is repeated throughout the spectrum, step 
by step, and a curve of absorption against the wave length of 
the spectrum is obtained.”’ 


FIGurE 88 


THE KEUFFEL AND ESSER COLOR ANALYZER IN USE AT THE BUREAU OF 
STANDARDS, 


The Keuffel and Esser Color Analyzer.—Several years ago 
the Keuffel and Esser Co. developed a spectrophotometer 


<e * Ind. and Eng. Chem., 18:8, 729. The Measurement of Color. C. E. K. 
Mees. 


Color Systems, Colorimeters, Etc. 245 
Se 
based on the ideas of Mr. Irwin G. Priest, of the Bureau of 
Standards, which has simplified the process of obtaining spec- 
tral reflection curves of an opaque body, such as a paint chip, 
or spectral transmission curves of transparent liquids and 
solids, to a great extent. While the Color Analyzer has been 
greatly improved upon recently over the instrument used in 
these tests, the underlying principle is the same. A descrip- 
tion of the instrument used, together with a discussion of some 
of the later improvements, follows. It is believed by the 
writer that this Keuffel-Esser Spectrophotometer is the best 
instrument of its type that has ever been developed. 


The instrument, which is a direct reading spectrophoto- 
meter, consists essentially of four parts: 1. A spectrometer ; 
2. A photometer; 3, A light source; and 4. A holder for trans- 
parent substances. 


1. The Spectrometer—To illustrate the principle of the 
spectrometer: if a beam of white light, admitted through a 
narrow slit, falls upon a prism, it is broken up into its com- 
ponent parts containing all the hues of the visible spectrum, 
Red, Orange, Yellow, Green, Blue, and Violet, and their vari- 
ous combinations. Now, if a movable screen, with a narrow 
shit cut through it, be placed on the other side of the prism 
and properly adjusted, only one color will pass through the 
sit. If the position of the slit be moved lower or higher, 
another color will pass through, ete. 


The principle of the spectrometer is the same. The hght 
enters through objective lenses and a fixed entrance slit, passes 
through a dispersing prism and out through a fixed exit or 
eyeslit. The only difference lies in the fact that the prism is 
rotated instead of the eyeslit being moved. The dispersing 
prism is mounted on a platform which is turned by a calibrated 
drum carrying a wave-length scale. To set the instrument 
on a particular color, or rather wave length representing that 
color, it is only necessary to turn the drum to that wave length — 
and the corresponding color will appear in the spectrometer. 


A bi-prism is placed in the spectrometer in order that the 
light may be sharply divided into an upper and lower half of 
the field. The upper half is illuminated by the standard, or 
block of Magnesium Carbonate, and the lower half by the 
sample to be tested. 


246 Color Systems, Colorimeters, Etc. 


9. The Photometer—The direct reading rotating dise photo- 
meter consists of two sector dises, each with two opposite 90° 
openings. The discs revolve around the same center and in the 
same direction. The angular opening between discs is set by 
means of turning the knurled head to which the photometer 
scale is attached. These alterations are made while the dises 
are in motion at high speed. 

The purpose of the photometer is to alter the brilliance of 
the block of Magnesium Carbonate so that a match may be 
obtained with the sample at the different wave lengths. The 
scale of the photometer reads from 0 to 110, and in the speci- 
fication of a color the settings of this scale are plotted against 
the particular wave lengths. The fact that the scale reads to 
110 per cent permits the approach to the matching point of 
samples of high reflection or transmission values from both 
sides, resulting in greater accuracy. 


3. The Light Source-——The light source consists of a 
spherical housing, in which are placed two 400-watt stereopti- 
con lamps. The interior of this housing is coated with a 
special white paint to give bright and diffuse reflection. Due 
to the high heat developed by the lamps, the housing is equip- 
ped with radiation ribs and the whole unit is ventilated and 
kept cool by a motor-driven suction fan. 


Operation of the Spectrophotometer—The sample and the 
standard block of magnesium carbonate are placed in the back 
of the housing. The light reflected from them passes out 
through the front of the housing toward the photometer which 
it enters. 

The spectrophotometer is operated by setting the wave- 
length drum on the spectromoter at, for example, 600 mu. The 
brilliance is then obtained by rotating the photometer scale 
until an intensity match has been obtained. Ordinarily paint 
chips do not show any particularly sharp fluctuations in the 
spectral reflection curve, so that a reading taken at every 20 
mu throughout the scale is sufficient. If, after the curve has 
been plotted, any sharp dips are found, the readings may be 
taken at every 10 mu for this portion of the curve. 

Some trouble in the past has been experienced with. the 
slight variation of different blocks of Magnesium Carbonate, 
some being whiter or less white than others. This has caused 
slight variations in the readings obtained on two different 


Color Systems, Colorimeters, Etc. 247 
La 
instruments. With this instrument each Magnesium Carbon- 
ate block is thoroughly standardized and certified by the 
manufacturers before delivery. 


The adjustment on the photometer to increase the illumina- 
tion of dark samples is so arranged that when the lever is 
moved the readings must be divided by four instead of by two. 
This adjustment increases the illumination of very dark sam- 
ples to a great extent and enables the operator to obtain a 
match easily in both halves of the field. 


FIGURE 89 


Conversion of the Spectrophotometer Readings to the Trich- 
romatic System.—Ives* gives directions for computing the 
Red, Green, and Blue sensations of a sample whose spectral 
reflection curve is known: 


*Journal Franklin Institute, January, 1923, page 43. 


248 Color Systems, Colorimeters, Etc. 


‘Multiply the reflection factor (given by the spectrophoto- 


meter) at each wave length by the Red, Green, and Blue sen- 
sation values and also by the white light spectral luminosity 


BRILLIANCE 


KEUFFEL AND ESSER COLOR ANALYZER 
BLUE GREEN YELLOW ORANGE RED 


WAVE-LENGTHS IN MILLIMICRONS 
Our results at the Bureau of Standards 
----~-Keuffel & Esser results their laboratory 


FIGURE 90 


TABULATION OF READINGS FOR ABOVE CHART 


Wave Our K. & E. Wave Our K. & E. 
length results results length results results 
+40 30.0 24.5 580 41.1 39.7 
460 S23 32.4 600 36.0 35.3 
480 39.8 37.4 620 34.6 31.8 
500 43.9 42.4 640 30.1 29.7 
520 49.7 47.8 660 29.3 29.2 
540 47.8 47.0 680 29.4 27.4 


Color Systems, Colorimeters, Etc. 249 
EASTMAN UNIVERSAL 
COLORIMETER HESS-IVES 
FIGURE TINT PHOTOMETER 

-GREEN -BLUE -RED NEUTRAL RED GREEN BLUE 
1OO Tere 
90 90 
80 80 
70 70 
60 60 
50 EO 
4O es 
Re 50 
20 Be 
10 1O 
O O 


—— Our results 


----Eastman Kodak Co. results their laboratory 


TABULATION OF READINGS 
Our KE. K. Co. 
resuits results 
REO ig fein gos ss ce es 0 0 
ol Se 4.4 Dak 
Oe 17.8 15.4 
MUMMIES. 30.9 30.9 


me. 


— Our results 


TABULATION OF 


READINGS 
ROU RA re er ee 30.5 
GLYCO cats edt 48.5 
BiG yah eee 38.0 
TLD ORLive eter 44.0 


CALCULATIONS FOR POLAR CO-ORDINATE CHART 


Our “i. K> Co: 
results results 


216° 


eee eee ote oer eee ee 


eee eee ee eee 


2 LUE 
10.25 


FIGURE 91 


value“ (given on page 25 of the same paper). The areas 
of the resultant curves, expressed as fractions of the areas 


*At the present time there is considerable controversy between color ex- 
perts with regard to what sensation and luminosity values should be accepted 
as Standard for the purpose of calculation. The method as given above is 


essentially correct. 


the near future. 


The standardization of these figures is anticipated in 


250 Color Systems, Colorimeters, Etc. 


of the original curves, are the required sensation and lumi- 
nosity values.’’ 

In the same paper is given a method of obtaining the hue, 
saturation, and brilliance of a sample whose spectral reflee- 
tion curve is known. 

Keuffel and Esser have devised a slide rule, by means of 
which these values may be calculated without involving higher 
mathematics, such as computing the area under the curves, 
ete. 

One of the objections to spectrophotometers in the past has 
been the necessity of using so many figures, or a curve plotting 
these figures, in specifying a color. By use of the calculations 
eiven above, or by means of the slide rule mentioned, a color 
may be specified by giving three values, the Red, Green, and 
Blue sensations. 


Hardy Recording Spectrophotometer.—Arthur C. Hardy, 
Assistant Professor of Physics, of the Massachusetts Institute 
of Technology, has recently developed a new type spectro- 
photometer. It has, however, not as yet been placed upon 
the market, and a complete description is not available. The 


following brief description of the instrument has been fur- 


nished the writer: 


The instrument is a recording spectrophotometer. The 
present model is designed especially for measuring the color 
of reflecting samples, and operates on the following principle: 
Light is alternately reflected from the sample and from mag- 
nesium carbonate. Both beams are caused to travel the same 
path and to disperse into spectral components by means of 
a prism. If at a given wave-length the reflecting power of 
the sample is different from the magnesium carbonate, an 
alternating light intensity is produced. This sets up an al- 
ternating current in a photo-electric cell, which eurrent is 
amplified and is used to balance automatically the two light 
intensities. At the same time a separate motor changes the 
wave-length under observation. A pencil moving on a drum 
draws the spectrophotometrie curve with good rapidity and 
with a precision exceeding that of visual instruments. 


Conclusions and Discussion.—Color charts are believed to be 
of limited value, for several reasons. A color-chart system, 
for instance, may contain several hundred shades or tints of 
one color, such as blue, but might not contain a blue which 


i a ee me 


7 


Color Systems, Colorimeters, Etc. 251 
ee ___.............___ 
would match a color chip selected by an individual. Color 
charts are usually prepared with flat or matte surface chips 
which are difficult to match with a gloss chip. Color-blind 
operators cannot use a color chart with any degree of ac- 
euracy. The influence of one chip upon another, because of 
the effect of color environment, makes comparison difficult 
when a chip is to be matched with a chart. On the other hand, 
color standards preserved in the form of color chips have 
always proved useful to the paint manufacturer. This is on 
account of the fact that the eye is possibly more accurate for 
matching colors than any instrument as at present developed. 
Thus, for instance, if a definite color (freshly prepared) is 
submitted to a manufacturer on a color chip, the manufacturer 
will be able to match it with greater accuracy than from a 
specification written from colorimetric readings. 


Because of the present lack of refinements in colorimeters, 
that would guard against experimental errors of a substantial 
nature, it is the writer’s belief that such instruments will not 
be of enormous value to manufacturers for ordinary work. 
Colorimeters could, however, be of service in the following 
manner. Suppose, for instance, that a paint manufacturer 
produces a colored paint or enamel, and that he paints it out 
and attaches it to his color card as one of his standard shades 
or tints always available to the trade. If he makes a reading 
on this color chip with a colorimeter, such, for instance, as 
the Eastman or Bawtree, he can record his readings for future 
use. If several months later he thinks some change in his raw 
materials has occasioned differences that give him difficulty 
in matching every batch of the same tint, he can then have 
recourse to his colorimetric standards. By setting the instru- 
ment to his recorded values for the color desired, he will ob- 
serve his original standard color which will guide him in 
matching up his paint. If substantial changes have taken 
place, he can make such adjustments in the formula as are 
necessary to lead him to the original desired tint. It was 
found however that black and many dark shades are of such 
low reflective value as to come outside the range of a colori- 
meter. Their use therefore is limited. 


Colorimeters might be of further use in the following man- 
ner: For instance, a color is desired in some far-off place, and 


252 Color Systems, Colorimeters, Etc. 


the reading on the color may be 20 Red, 40 Green, 30 Blue. 
Several days’ time might be required to paint out a sample of 
the material, dry it, and then submit it by mail. Telegraphic 
communication, however, could be made, stating that paint of 
the above specification was desired. Within a few minutes’ 
time the reader in another section of the country could set his 
colorimeter to the specification, observe the color desired, and 
match it fairly well. Thus specifications could be transmitted 
by telegraph and be thoroughly understandable. For military 
purposes such a method would be useful. 


Asa result of growing interest in the subject of color defini- 
tion, instrument manufacturers are making rapid progress in 
the development of colorimeters. Instruments of even greater 
accuracy than those now available may possibly appear in the 
near future. It is believed that such instruments would be of 
value in any paint laboratory. 


With the tint photometer used in our work, observable 
differences were recorded between colors that although very 
similar could also be differentiated by the naked eye. Read- 
ings, however, were made only upon one instrument and by 
one observer, and comparisons cannot be drawn as to the rela- 
tive accuracy of two different instruments of the same make 
when read by various observers. For matching old colors, 
this instrument could not be set up with recorded values given 
in red, blue and green, as has been referred to above, with the 
ordinary type of colorimeter. It will be seen, therefore, that 
its use in this direction would be somewhat difficult to apply, 
whereas, of course, three readings could be set individually. 
For this reason the ordinary colorimeter referred to above 
might prove superior to the tint photometer, although this 
latter type of instrument is relatively imexpensive, easy to 
handle, easier upon the eyes, and possibly more accurate. 


If a manufacturer should make a reading on a color chip 
with the spectrophotometer and then desire at a later date to 
see whether any changes had occurred in the chip or in the 
paint made with the formula, this instrument could not, of 
course, be used for reproducing the color. His method would 
be to submit his paint to a reading on this instrument and 


Color Systems; Colorimeters, Etc. 253 


ascertain whether any change had taken place. Two colors 
giving the same reading on the spectrophotometer are always 
exactly alike to the eye under all conditions of illumination. 
It is possible, however, that two colors giving different read- 
ings on the spectrophotometer might also give the same ap- 
pearance to the naked eye, such, for instance, as camouflage 
colors. A rather long time is required to make readings on a 
spectrophotometer and the instrument is relatively expensive. 
Normal color vision is not needed to operate it. A specifica- 
tion for a color according to a spectral reflection curve could 
not easily be transmitted by telegraph. If received by mail, 
one familiar with color work could immediately get some idea 
as to what the color referred to looked like, but it would be 
necessary for him to experiment with several different tints 
and shades of the color before he could match it exactly on 
the spectrophotometer. It is without doubt the most accurate 
instrument for defining a color. In large laboratories it is 
believed that the spectrophotometer would be of considerable 
use and perhaps of value. 


i 


In the control of color in the paint industry, long experience 
has demonstrated that in a mixture of pigments a fixed for- 
mula cannot be relied upon to produce a series of ‘‘batches”’ 
all uniform in color, no matter how accurately the propor- 
tional quantities may be weighed, or measured. It has also 
been established that, in a series of ‘‘batches,’’ if each batch 
be matched up to the batch immediately preceeding, there 
will ensue a ‘‘drift’’ away from the original color that soon 
becomes pronounced; and this occurs whoever does the 
matching. 


To minimize difficulties of this kind, it has been customary 
to match the different batches in process of production up to 
daily ‘working standards,’’ which, in turn have each been 
checked against a carefully preserved master standard, which 
is presumed to have remained practically unchanged. This 
master standard is usually a sufficiently large portion from 
some original batch whose color has been adjusted to a shade 
arbitrarily chosen as the desired standard, this portion being 
then filled into a number of small packages, hermetically 
sealed, and set aside for future use as required. 


254 Color Systems, C olorimeters, Etc. 


Such standards cannot, unfortunately, be relied upon to 
maintain their integrity for an indefinite period of time; conse- 
quently, it is highly desirable to have available some scientific 
method of measurement or specification that would positively 
identify the color of any selected standard, enabling a record 
of it to be kept in quantitative terms of fundamental physical 
units. 

Color is a psychological sensation and as such is not readily 
measurable, yet the stimulus or immediate cause of the sensa- 
tion is easily measurable, and expressible in terms of funda- 
mental physical units. The additional fact that a definite 
stimulus excites the same specific response in all individuals 
possessing normal chromatic vision enables the spectral re- 
flection curve to be employed as a sound indirect measure of 
color. 

In setting up color standards for the purpose of uniformity 
of color in any commercial commodity, the real objective de- 
sired is a fixed and definite stimulus value, this being, in fact, 
the only part of the complete process of color vision over 
which the manufacturer of the commodity can hope to exercise 
control. 


To sum up the principal points in connection with spectro- 
photometry as a method of color analysis, the recent work of 
Sub-Committee XVIII, D-1, of the American Society for Test- 
ing Materials might be referred to, the line of reasoning being 
developed as follows: 


First, when a painted surface, or other object, is suitably 
illuminated in such a manner that the character of illumina- 
tion can be specified, the incident radiant energy is reflected in 
a selective way. Second, the inherent properties of any 
sample of radiant energy which determine its capacity as a 
color stimulus are completely specified by its spectral distribu- 
tion. Third, the spectral distribution is fully exhibited in the 
spectral reflection curve; consequently, so far as the manufac- 
turer is concerned, the curve serves as a measure of the color 
of the product, and specifies the sensation that will certainly 
be produced in the eye of every observer who possesses nor- 
mal chromatic vision. 


The great value of the curve to the manufacturer of paints, 
or other objects involving similar color problems, lies in the 
fact that it may be preserved indefinitely as a permanent 


me 


Color Systems, Colorimeters, Etc. 255 
as 
record of the stimulus value of any original standard, and if 
any such standard should change in color, either from long 
storage, exposure to light, or other cause, such change can be 
detected, its extent measured, and the true color restored or 
a correct new sample prepared, without SUS comparison 
with any other sample whatever. 


PartiaL List oF Books on Couor FoR REFERENCE WorK 


Color and Its Applications. M. Luckiesh. 

Color and Methods of Color Reproduction. Martin and 
Gamble. 

Color. G. W. Thompson. Proceedings A. 8. T. M., 1923. 

Color Standards and Nomenclature. Ridgway. 

Farbenfibel. W. Ostwald. 

Die Grundlage der Messenden Farbenlehre. W. Ostwald. 

Die Farbenlehre I, I]. W. Ostwald. : 

Die Farbe. W. Ostwald. 

The Theory and Practice of Color. Snow and Froelich. 

Farben, Farbensehen. Carl Hensel. 

Traite de la Couleur. A. Rosenstiehl. 

A Handbook on the Theory of Color. G. H. Hurst. 

The Colorist. J. A. H. Hatt. 

Systems of Color Measurement. H.S. Busby. A.S. T. M. 
Proc., 1922. 3 

Problems of Color Measurement. H.S. Busby. A.S. T. M. 
Proc., 1921. 


SECONDARY REFERENCE SAMPLES FOR TINTS 
AND SHADES 


Reference is made at the beginning of this chapter on color, 
to the old type reference standard in use in paint factories. 
A request from one manufacturer for information as to the 
best method of keeping such standard samples for shades 
and tints of house paints, was submitted a few years ago by 
the Secretary of the Association to a number of technical ex- 
perts in the industry. The answers received showed a wide 
diversity of opinion on the Spares They are summarized 
below. 

(a) For the past twenty-five years all standard samples were tinted 
on a base of “Green Seal” zine ground in light colored paraffine oil in semi- 
paste form in the regular manner. 


We find that delicate colors, such as light blues and greens, in fact, any 
color, does not change its shade. The only thing is that a tinter that matches 


256 Color Systems, Colorimeters, Etc. 


the shades must allow for sample color being cleaner and clearer in tone 
than the color he gets by tinting the regular paint. 

(b) We know of no vehicle which may be used with pigments which 
will not change color on storage, whether exposed to light and air or kept 
sealed. The most satisfactory way to set a standard shade is to use raw 
materials of given specifications and make sample freshly each time color is 
to be determined. We have not carried on any extensive experiments along 
the lines suggested, but do not believe that it is feasible to use neutral 
mineral oils, as these will not allow for the difference in color between the 
dry and wet paint where drying oils are used. 

(c) Standard samples ground in corn oil to a paste consistency, using 
zine as the base for tints made from white bases, will give very satisfactory 
results. I have also used neutral oil to some extent, but believe the corn oil 
better for general work. 

(d) When making up house paints, we match them with the dry sample 
on the color card and also with a sample taken from the last batch made 
and in this way we keep the shade uniform. 

(e) We do not hesitate to say that no thoroughly satisfactory method 
has yet been devised. 

Any proposed method must depend upon factory procedure, that is, 
whether the shading is done in the liquid mixer or while the batch is m 
paste. Both ways have their advantages and disadvantages and depend on 
the plant. 

With proper care and attention coupled with a reasonable experience, 
we do not have any appreciable complaint which might justly be laid at 
the door of any improper standard, but in this connection we might ask the 
pertinent question, “Why should a properly kept standard change if the 
goods themselves hold their integrity after being filled and stocked?’ If the 
goods do not hold, without radical or pronounced change, for the indefinite 
time they may remain in stock, then high accuracy in a standard type sample 
becomes obviously an unnecessary refinement because neither the rate of 
change nor its final extent can be predicted, no matter what the starting 
point. 

There are limits, of course, but scientific accuracy in such cases is not 
to be attained by the use of a perfect type sample. 

What, for instance, is the use of a perfect type sample of a pale tint of 
Chinese Blue in lead or zine? After the goods have been in the ean a few 
weeks, or less, the shades will never again match exactly the “perfect 
sample,” although upon being painted it will “come back” more or less by 
the time the paint is dry. F 

These little problems are a part of the paint maker’s art and must usually 
be solved by each one for himself, according to his ability and environment. 

Glycerol, paraffin oil, refined linseed, poppy oil and» various other vehicles 
have been tried with varying degrees of success, but we find that after all 
it is perfectly practicable in the vast majority of cases to secure reasonable 
uniformity by working from a type sample taken from a regular commercial 
batch. The complaints arising from variations in shade, due to imperfect 
type samples, are wholly negligible when compared with the howls that 
come in because the paints in the cans do not match the color cards, and in 
both cases the complaints come almost invariably from the inexperienced 
consumer. 

(f) colors ground in water-white mineral oil will hold their color 
permanently on storage. Such colors ground up in order to maintain stand- 
ard colors should be kept in opaque or very dark colored, tightly sealed glass 
Jars, properly labeled for identification. 

(g) We use straight refined linseed oil in grinding out our standard 
shades for house paint colors. These we use for one year to shade to; then 
we regrind for new standards to be used in the future. 

(h) We have always ground our standard samples in winter strained 
lard oil and have found that this held the color very well. 

(i) Our experience is that if these samples to be retained as standards 
for matching work, are ground in pure winter strained and refined lard oil, 
there will be as little action as can be had with any oil with the added ad- 


Color Systems, Colorimeters, Etc. 257 


vantage that they will not be as likely to skin over. In removing this skin 
some of the tinting color is lost; however, on delicate blues and greens, 
there is always likely to be some fading. 

(j) We have experimented with various methods of maintaining stand- 
ard samples for shade on house paints, and find that a good grade of zinc 
oxide ground in corn oil, tinted to the standard color with pure coloring 
matter, will retain shade better than anything else we know of. 


This information was received. previous to the study of 
colorimeters and spectrophotometers which is given above. 
These instruments have just come into the industry and as 
yet but few laboratories possess them. Until laboratories are 
equipped with such instruments and with personnel to prop- 
erly operate them, they must rely on the older methods of 
keeping standards. In this connection, it is probably wise to 
again point out the fact that the eye will more readily detect 
very slight differences in a tint than will a colorimeter. For 
this reason, if secondary standards could be developed, they 
would serve a very useful purpose in the industry. 


A method which the writer has been experimenting with 
during the past summer, consists in applying to very thin, 
clear glass plates four inches square a quantity of the color 
of which a secondary standard is desired. The plate is spun 
to produce a thin, uniform film. The coating is allowed to dry. 
Previous to the spinning operation, it is absolutely essential 
that the paint be thoroughly screened to remove all specks. 
After drying for a period of one day with interior flat wall 
paints or four days for exterior oil paints, one-half of the 
surface of each panel is flow-coated with a thin nitrocellulose 
lacquer made by mixing together 100 parts by weight a 32 oz. 
solution of 14 second viscosity nitrocellulose in butyl acetate 
and 150 parts by weight of toluol. Five parts by weight of 
tricresyl phosphate is added as a plasticizer. This lacquer 
will usually dry in 15 to 20 minutes under normal conditions, 
and but little difficulty has been had with the lifting of the oil 
films over which it is applied. It is, of course, necessary that 
these films should be quite dry and firm before the lacquer is 
applied. 

These panels are kept as reference standards, and when a 
batch of paint is to be tested for color, a portion is placed 
upon an uncoated plate of the same type of glass, flowed out, 
and a comparison immediately made. The operator views the 
color in comparison with the secondary standard, looking at: 
the top surfaces and then reversing the plates and looking at. 
the under surfaces. The purpose of the lacquer is to serve as: 
a continuous film to prevent oxidation of the color due to long 


258 Color Systems, Colorimeters, Etc. 


standing. It also serves to present a type of surface which 
appears wet and therefore is useful in comparing the color 
of wet samples. 

Tests made by this method, in which the coated specimens 
were kept for a period of three months in a dark moisture 
saturated chamber to cause darkening, indicated that but little - 
darkening or change in color had taken place. 


The method, however, is not perfect by any means, and is 
simply offered as a suggestion for further research on the 
part of laboratories having this matter under consideration. 
It is not recommended for adoption. 


CHAPTER XVI 
OIL ABSORPTION TESTS 


Probably the most widely used oil absorption test is that in 
which the pigment is rubbed up with a spatula with sufficient 
oil to just form a paste. This quick and convenient method 
usually gives results which are comparable with the oil re- 
quired to grind pigments in a mill to paste form. It is out- 
lined below as a standard test and is to be preferred for most 
factory control work. There is also given below an outline 


Brown Burette for Oil With 1 cc. Pipette Graduated to 1 /10 ce. Main 
Bulb Holds 100 ce. 


FIGURE 92 


of the Gardner-Coleman method for determining oil absorp- 
tion, which, while giving valuable information regarding cer- 
tain characteristics of a pigment, is not used widely in paint 
factories. Its chief application is in pigment factories where 
close control of each batch of product is a matter of great 
importance. 

The rather extended discussion of this method which ap- 
pears in this chapter may be excused because of the desira- 
bility of presenting an explanation of the phenomena involved 
when pigments absorb oil. 


260 Oil Absorption Tests 
RR RNE SEIT 

Standard Rub-Out Test For Oil Absorption.—Take exactly 
one (1) gram, or any multiple thereof, of the pigment. Place 
upon a marble slab or glass plate, carefully weigh a dropping 
bottle containing some refined linseed oil, the bottle to be 
fitted with a ground in pipette and rubber bulb. Note the 
weight of the bottle and oil. Gradually add, drop by drop, 
the refined linseed oil to the pigment, and after the addition 
of each drop, by the use of a stiff spatula, thoroughly incorpo- 
rate the oil with the pigment. The test is complete when ex- 
actly enough oil has been incorporated with the pigment to 
produce a very stiff, putty-like paste, which does not ‘“break’’ 
or separate. Weigh the bottle and oil. The difference in 
weights equals the weight of oil used. Calculate to pounds 
of oil required to exactly ‘‘wet’’ one hundred (100) pounds 
of pigment. : 

In the writer’s laboratory the type of burette depicted above 
is used for conducting this test. The number of cubic centi- 
meters of linseed oil used is multiplied by the specifie gravity 
of the oil in order to obtain the weight of oil required to satu- 
rate the pigment. This test has been run upon a number of 
pigments found in the laboratory, with the results given below. 
Some of the pigments reported on had been in the laboratory 
for several years. Slightly different results might be obtained 
with more recent samples. 


Or ABSORPTION ON SomE PIGMENTS BY SPATULA-RUBBING 


MrrHop 


Figures show pounds of raw oil required to form a paste with 100 pounds 
of dry pigment. 
WHITE PIGMENTS 


Zine Oxide (Western Leaded). 13 China. Glay =o... tgs 29 
Zinc Oxide (Western Leaded). 12 Tale ....<. iets eee 37 
Zinc Oxide (American Process) 21.5 Asbestine (pulp)-< 234-5. scne 29 
Zine Oxide (French Process) .. 19.5 White Mineral Primer..\.....5 13 
Zine Oxide (French Process).. 16 White Mineral Primer......... 14 
Lithopone (low oil absorption) 14 Whiting: ¢Gilders) (255 eee oe 
Lithopone (light-proof) ....... 18.5 Whiting .(Gilders) sa. ..ee ae 17.5 
Zine, Carbonate acnssea eee 38 Whiting -(Wloated) tae nee 15 
Zine “Sulphide 0.46 kijeewe eee 26 Whiting. 12.20%. eee 17.5 
Titanium Oxide 2 <3. sess 45.5 Barytes «..¢.5 sas eee (es 
Titanium Oxide (pure)....... D1 Barytes «s.2, » +s ssl en ee 9.5 
Titanox (Calcium sulphate Blane Fixe .os.:45) <a 5 eee eee 15 
DSO): Gn} sale Oo cke eee cares 29 Barium Carbonate \3e2 eae 16 
Titanox (Calcium sulphate Gypsum (Hydrated) ......... 29 
DEBE)“. vend See 23 GYPSUM +... eve ele eee 20.5 
Titanox (Barium sulphate Bentonite Clay.) 225 seeeeeee 24 
DASCY Va cutee ee se ee eee Zi. Silica (Floated) (32233. a0a eee 29 
White Lead (corroded)....... 10 Silica (Crystaline) 23.5 e508. 16.5 
White Lead (basic sulfate)... 138 Diatomaceous Earth ......... 29 
Antimony Oxide. 2 7601 14 = OO la 152 


Ching Clay .-.0.6 2 see eee 30 


Oil Absorption Tests 261 


RED AND YELLOWS 


American Vermilion .......... 9.5 
Deep English Vermilion....... 10 
Eee yc. vise ce eee 11 
ie 10 
Deedee MINCrAl . 06s. .s ee ee es 11 
Tuscan Red (24% Fe203)..... 16 
Tusean Red (28.5% Fe203).... 23 
Orange Chrome Yellow........ 9.5 
Orange Chrome Yellow........ 12.5 
Orange Chrome Yellow (deep). 11 
MUMBEREES Std Ss Go ee ee eo ss 31.5 
Deep Para Red (10% Para on 
Whiting-Barytes Base)...... 16 


Maroon (10% Alphanaphthyl- 
amine in Whiting-Barytes 
I erty. oN ais 6s oes o's 20.5 

Ortho Toner (90% Orthoan- 
isidine on Lake Base)...... 54 

Ortho Red (10% Orthoanisi- 
dine on Whiting Base)...... 23.5 

Searlet Lake (35% Xylidine 
Searlet on Blanc Fixe Base) 29 

Methyl Red (2% Lithol on 
orange mineral base)....... 12 

Orange Lake (16% _ scarlet 
Manderine on Whiting-Blanc 
ROTO ore he oe eee 21.5 


TROSG oe LO ae eta e nee ace ae ee Shae 29 
Toluidine Red (50% on Blanc 
BLS OW ISHBO badectoniclarw sity: ohohen ails 30.9 
Venetia no Gel avs c.c eh mie es ola tine 21.5 
AVL S Tie PUCUGi a bs rene ce oni fe ate 13 
Indian Red (96% Fe203)..... 18.5 


Prince Mineral (34% Fee203).. 23 
Metallic Brown (61% Fee03).. 16.5 
BURDISHLOSIGG cise cent se o's 15 
Purple Oxide (82% Fe203)... 10 
Canadian Oxide (91.5% Fe203) 25 
Italian Raw Sienna 


; (G4 orb eos Siete cas ce nates 52 
Raw Sienna (American)...... 40 
Burnt italian Sienna >... ...... 28 
RUTH Ue LOT Dg ie a teases etal oa 28 
FLL OCT aie cay So erete dee, ateela oo 26 
Raw Turkey Umber 

FAG Tom Bea Os \eicre es Ghee ares 44 
Burns (MDS es ees ate gtostacs 39 
Golden Ochre ..... 1 oR RRR 16.5 
Yellow Ochre “F. A. R.”....... BH 
Ochre (American): ........... 18.5 
Ferrite Yellow (Dark Orange). 32.5 
PO elie Pitile coe etttens debates a okes 29 


GREENS AND BLUES 


fMrramerine Blue ............ 35.5 

Medium Grinding Green (30% 
green on clay Barytes base) 12 

Extra light chrome green (14% 


on Barytes-clay base)...... TS 


Medium Chrome Green (16% 


Strong Grinding Green (16% 


on Barytes-clay base)....... 17.5 
Blue Shade Green (16% on- 

Blane Fixe-clay base)....... 11 
Chromium Oxide “Pod... 3: si... 32 p bres" 


Blue Lead (Basic Sulphate)... 7.5 


on Farytes-clay base)...... 16 Blue Lead (Basic sulphate)... 12 
Dark Chrome Green (16% on 

Barytes-clay base).......... 16 

BLACKS 

SS 27 Lampblaek seit oeate se ais 107 
EE ory aig a we cos ye 4T.5 Beaampp la Chtt,sc tes eras le oa 111 
Se 39 Thermatomic: Black 2) .vao..: 31 
UMMM ACI ey oo ww 93 Keystone: Fillers. 2. ee tas 19.5 
Des OL ALOE a 99 Black Iron Oxide _ (Precipi- 
ROR Gh ee ee 114 tH CCUY Bes tha capes ore aes 33.0 


It should be pointed out, however, that there is no sharp 
line of demarcation for any given pigment between a paste 
obviously too thin and one just as obviously too stiff. It 
should also be pointed out that the wetting power of the lin- 
seed oil used is profoundly changed by oxidation, acid value, 
and all types of refining and cooking. The greater the oxida- 
tion, the greater the wetting power as arule. It might further 
be mentioned that it is sometimes difficult, when using the 


262 Oil Absorption Tests 


same grade of linseed oil, to obtain pastes having the same 
vield value or mobility with pigments of the same type from 
two different sources. 

One might reasonably suspect that if the absorption were 
expressed in terms of volume instead of weight there would 
be a closer concordance, and that perhaps it might show a 
definite relationship to specific surface. Microscopie examina- 
tion, for instance, of zine oxide shows it to be as fine or finer 
than toluidine red. While the zine requires approximately 
1.22 volumes of oil to make a good paste, toluidine red, with 
a presumably smaller specific surface, requires about 2.10 
volumes. Instances of this sort may be multiplied, and such 
discrepancies force us to the conclusion that the interfacial 
tension between pigments and oil is not only different for the 
different pigments, but with linseed oil the factors which 
govern oil absorption, may become an extremely complicated 
matter. 


OIL ABSORPTION OF PIGMENTS* 


In the following table, the figures give the percentage of 
pigment in commercial pastes made by grinding the pigments 
with reasonably fresh raw linseed oil practically free from 
foots and having an acid number between 2 and 4. 


WHITES 

Aluminum Hydroxide (Commercial Hydrate).............. 40-43% Pigment 
Asbestine 2.455 ¢5008 s 00's wie shames sweaty Cee nn 68 
Barytes 2. oie avaaes wen seen Oe ev ewe ae sete 94 
Blance Fixe .....5 600.006 ¥ ss buw oul cule be Sele 88-90 
China Clay ‘(Dry)....... ...scucsssbeee eee eee 70 
Lithopone © 2. oi... ences caus ae ne Uy eee Oot 82-86 
Silica «(Quartz)) oo ..a ii a oe de eee es ee 73 
Titaninm Dioxide’ .....42.002 22... 4 eee hale oe 35-40 
Titanox (25%. TiOe) 2. 05. cota ws eee 80-82 
Whiting 2... i ees cuba ded bone 63) 
Basic Carbonate White Lead (Dutch Ee ee he et eo 91-92 
Basic Sulphate White Lead: ....... is..:...000eeee 88-90 
Flake White Lead..........0-be0es0ss pies tl 88-89 
French Process Zine Oxide..::..42.........50 80-83 
American Process Zine. Oxide (Lead-Free) . ....: 4.20.0 seeen 80-83 

= se: (Leaded)  ....4: Seeneaeeeeee 83-86 

BLACKS 

Carbon Black (Gas) ...cc.ssvc0-4.4 enue. — 
Drop Black 3) I as er oe ete 
Ivory Black (Genuine) ......:..1,..0,1.)..., 0 3 
Lampblack os. 4i6 cs. V0. ed boa oe an ee a 28-34 (Note 4) 
Iron Oxide Black (Artificial) ...:..........2..) 00 82 


*Table furnished by.F. P. Ingalls, 


Oil Absorption Tests 263 


REDS 
EEE i S00 SP 86-87 
af “i NO pce a caatats Liss lui's c's; enue sai sng a bc 0Nb 86-87 (Note 5) 
sg a lacs ain ala eos es e's vane os 6 ets es 43 
a 40 
tn ess cio 5m 2 8 oy te et ee eee ees Rerokind i tre rene oi 40 
aca saison + < sc 6) 90 00 0-40 whe ta te vs 60 ee 70 
meeeneyvermiion, Pale and Deep............ceewecccccecs 84 


Note 3—A paste containing as high as 20% of a “long” black could be pro- 
duced, but it would be very stiff. A “short” black is quite firm at 12%. 
Carbon black is difficult to disperse in raw oil. Special vehicles are usually 
employed. 

Note 4—Some lampblacks grind shorter than others. Perhaps 380% is 
a good average figure. Even in this concentration, if too stiff, they might 
“streak” when used for tinting whites. R 


Note 5—This color is the crystalline basic chromate of lead. 


SE a cgtina ashe 35 (Note 6) 
SIGS 88 ( Note7) 
a gC cia la ty a,c ace 00s. @ae 60h 'e sista ey 0oe biapee ace 82 
Lithol a OS aera AT 
- SERIE Pe ee ree ee, Si er arr 42 
UIE A TIZATING) . 0... ws ee he cee ee ees sensens ‘40 
TE AC ec cn pe oe esc wns vices sp sineenveceus 39 
sr eee na ox 5 sien Ge bas oe bie Kaleo hbo ole be 42 
Maroon Toner (Alpha-naphthylamine).................... 30 
Paranitranilin SMI ANG ES cre oe I el Ow ale ci ome C ae 6 ow, baa a 43-47 (Note 6) 
EA LNCS iirer Pro fe aa) 6 ask ais od a(tre es Fk ke v0 30-40 
eng See cv veep en cd ced pe verssvceass 93 
pee BAKE... 66.3 ok ee eon nse hs tis coat ate & Aaale ele 71 
re oe sis pu bis Sele ale as oa be mews ba Cae a's 74 
SG O08 0S a 42-46 (Note 6) 
I RR ele ac eng ce cts ced ceed ebeyecceuas 80-82 (variable) 
Venetian Red (Government Standard)..........-esecceee. rue 
Set Fie tett COKIGC J ae eee te bg te cease 78 
“s ee TIE CEU G 0) 9 io ann ie bees c chele viesd duerele Se we ote 78 
YELLOWS 
Cadmium NITE es ANTI oe oar. hoes aie cheteaie oak Gdn ease aleve wes 79 
“ PRED TA Ae koko eS, fears ateie Ate te Ses Seo celten viet 78 
: a Lg Fer a tek A IRR ace RIN) eer tN rts oa 86 
i etree aie (GENUINE) . 00.6 cee ce coe a dae ole 5D 
“ i Med. Seater kh aoa etre cone acs Sree hte 55 
- st a Be Moc Sa ety eG Bs win hk hee to ae Pe 60 
cm Se nl 6 yon Sod GS ety cya eS opie We RRA Ee taate Sk 80 
I e520 E I o. ) i. cc ee ee we ae eectaadvulecss 78 
bi SOME Sti, she Sacha ts We Siad-whe pate aie hares 78 
8 . LL ee 213 A RR Seo ae ee a 80 
a Memes Mert ere ee Mat a Me ere ee Bae 82 
ps “ Me VE ATI osc ao ane ake hd ws occ wade oe nk 87 
NE ne i in cc bee da bee eee uaveun 70 
Merteereseriicinl OCHre) .........0.cseccenecuvecscecbcces 65 
MPT ICH IE. 2. cis. cw cc sees ew ccvudedanuvaceucs 71-73 
Yellow Lake (Genuine Persian Berry).............eeceeee 30 
Peteretiow (Basic Zinc Chromate).....5....0-..eeses000% 74 


For this reason a special grinding liquid is generally employed. Pigment 
concentration would vary according to the wetting power of the special liquid. 


Note 7—This is straight orange mineral toned up with about 1% to 144% 
of eosin. They are sometimes called French Vermillionette. 


Note 6—Dry red toner and para and toluidin reds grind short in raw oil. f 


264 Oil Absorption Tests 


GREENS 
Chrome Green, Light... 26.0 @. ccus« ns 00 6 ese + eens gee 86 
rD Medium a. sc tin oe oS One 85 
Fg - Darks) ccccls Leis whe bah nage Oe 82 
Chromium Oxide (Anhydrous) 3........%% 4. + «Sale» pee 88 


(Hydrated), also known as Emeraude 
Green, Vert de Guignet and Viridian.. 50 


Yobalt Green (Genuine, Cobalt and Zine Oxide)........... 60 
Emerald Green (Paris Green) .. 2... 00's «s+ belo 80 
Green Lake (coal tar dye precipitated by means of phos- 
pho-tungstic acid) <2... 0 .sh eve ewe nee s oe eo ee 40 
Verdigris (Basic Copper Acetate) .... ....<1.es as eee 70-75 
BLUES 
Cobalt Blue (Genuine Cobalt Aluminate).................. 40 
Prussian Blue (and Chinese)... i... 5% << « sw 5) «lhe eee 44-48 
Ultramarine «i... sev ee bclen’s © bum sw oases ictee Ge one 43 
Sublimed- Blue Lead =)... 32. eee eee oe 8 4 0 es ae eee 88 
BROWNS 
Brown, Metallic «444.75. e Lee ee er 78-80 
Sienna, Burnt ...40.. 64 0% 6 o » ce is ew © ole acai ol wl ie ee 51 
az FRO W «aie wn oes win 5 + clad ck oe utersun mW ce eee ee 50 
Umber, Burnt oi. ec ois cp Wisle ee oe wore ole ig eee 52 
Zs FRA W oo so ais is: tule 0 i Oni w wl cln'e: gimme ey lene eeataety ennn oz 
Vandyke Brown . o. o0sstess che wes 8 ccna e «1b op tol cle 53 


Or ABSORPTION OF VaRIoUS PIGMENTS* 


100 lbs. of dry pigment requires the number of pounds of 


raw linseed oil shown below to form a paste: 


Basic Lead Carbonate... 5.06.46. 00s ces ss 0k eee 11 pounds 
Basic Lead: Sulphate-icoeucank 2s oeae RP 11 
Lithopone . 2.2... ewes bas ghee se wa seu 5 noise eee 25 ni 
39% Leaded Zine... oc... 6 i sua vale 0 se Ulge lee ale lena 14 si 
American Process Lead-Free Zinc.....5 +. <..00 a eee 25 ns 
French 4 3 " fea bab ba oe ke Se 25 Ca 
Titamox is os we coe Vv hw bu one eee ee eee ee mete aI ie 
©. P. Lemon Chrome Yellow..........4 -005 ., see 40 sy 
C. P. Medium Chrome Yellow. ..:......0.... 35 . 
C. P. Deep Chrome Orange....0.....0¢...15. 02 eee yao 6 
C, P. Chinese Blue 1... ...005 S00 deen dec ces ca pee) ee 80 bs 
C. P. Prussian Blue vy 2.05 ssa. cen pues «oc geey on eee 140 s 
Ultramarine Blue . 2... 000.4405 0s sey eos Goa oe 45 = 
C.P. Chromium Oxide .....2: 0021.0) .8400 15 ie 
C. P. Light Chrome Green.......:..0.0:3+00e8 0 40 . 
C, P. Medium Chrome Green; . 2: -..,4. 0.45...) 50 we 
C. P. Deep Chrome Green... 2... ....+-50.s0c cue 60 i 
25% Light Grinders Chrome Green... .........00 ee 30 os 
25% Medium Grinders Chrome Green.......<...... ee 35 
25% Deep Grinders Chrome .Green............)) so 40 4 
C..P. Lithol Toner oso. ae eee 3a ee 120 
Madder Lake 2... .5040005 ss un wleae ee oie one cle 160 sf 
Bordeaux Maroon Lakes, ;.....¢s<<s0+sceecac se) 50 a 
C. P. Light Para Toner... ¢. ...4.4 ene. waa AO sa 


*Table furnished by A. F. Brown. 


66 ee ees . 
+ a 


Oil Absorption Tests 


265 


Lene ee ———EEEEoEo—EEEEEEEEE——==us 


SIE EM POMCT. .. 6. eee ew teeters tees ewrcnseens 150 pounds 
10% Light Para Red on Calium Carbonate................ Se eaae SOG my 
10% Deep « aa eae : ee eee Pe Vie er dese teh pith a: a one 35D i 
eT a a vise eis tie ese ce bcos ee sew eeccee Pee af 
PERMIT TTL sos ke see es RE ANE ee ET Cl ego. one ek are s-ahass fae tend) 40 * 
momrier Lakes .....25.0...5- ae ee I ROE ee Peace Nee See OU “ 
RINT TIGITIG PONCE. 2... ce ete eee eSNG Soc sa a a LOO 
PUMICE EOI SALYLCS. 0c ce ce te te eee nee eee e seers 25 a 
feminine on Calcium Oarbonate................0. eee eee . 60 " 
CPN ONTOINALG. soe ek cee wees Se Se OE 3 aes, seh ee gay eae 2-40 As 


FIGURE 93 


Apparatus Required for Determining Oil 


Absorption of Pigments 


266 Oil Absorption Tests 


Fasig Oil Absorption Number.—kK. W. Fasig of The Lowe 
Brothers Co., in commenting upon the Gardner-Coleman oil 
absorption test, states that instead of using a spatula to mix 
the pigment in oil, he puts the pigment in a mortar and grinds 
it with a pestle. The oil is dropped into the mortar by means 
of a burette. The end point is sharp. The advantage of this 
method, according to Mr. Fasig, is that the results obtained 
from the test can be used in actual mill practice. Thus, for 
instance, in the case of zine oxide, he secured an oil absorp? 
tion of 18 per cent. The same oxide, when ground to paste 
form in actual mill practice, showed the presence of 82 per 
cent of pigment and 18 per cent of oil. 


Gardner-Coleman Oil Absorption Method.—In mixing a 
pigment and a liquid a point is reached where independent of 
such mechanical forces as could be developed by actual grind- 
ing, the surface of each pigment particle is thoroughly wet 
by the liquid and the pigment mass becomes thoroughly satu- 
rated. This point represents the oil absorption property of 
the pigment, and is expressed by a factor termed the oil ab- 
sorption factor. This factor is therefore a measure of the 
quantity of a given oil or liquid, required to thoroughly wet 
all the absolute particle surface of the pigment mass. The 
factor is ascertained by determining the number of cubic 
centimeters of liquid required to saturate 20 grams of pig- 
ment. It is then expressed as the amount required for 100 
grams of pigment. 


In designing a paint the oil absorption factor is especially 
important. Thus if it is desired to increase the consistency 
of a paint without increasing the percentage of pigment, high 
oil absorbing pigments may be used. The opposite may be 
accomplished by the use of low oil absorbing pigments. In 
using high oil absorbing opaque pigments, inert pigments of 
low oil absorption may be added in order to lessen the amount 
of oil required to suspend the other pigments. When it is de- 
sired to secure maximum opacity, regardless of other quali- 
ties, a low oil absorption opaque pigment may be used. If a 


glossy enamel-like finish is desired, a pigment of high oil 
absorption is indicated. 


The amount of oil required for pigment saturation or wet- 


Oil Absorption Tests 267 


ting is directly proportional to the specific surface* of the pig- 
ment mass, existing at the point of saturation. As the specific 
surface of the mass is relative to its degree of particle sub- 
division or fineness, it also measures to a great extent the fine- 
ness of the pigment. The oil absorption factor being relative 
to the surface conditions of the pigment is independent of its 
chemical composition or specific gravity. The practical ad- 
vantages of knowing the oil absorption factor le in the infor- 
mation it gives concerning the following physical conditions 
of the pigment: 


(a) Relative amount of surface in the pigment mass. 

(b) State of sub-division of the pigment particles. 

(c) Comparative specific surface of various pigments. 

(d) Variation in fineness or particle sub-division of various 
lots of the same pigment. 


The property of absorbing a given quantity of oil is relative 
to the specific surface of the pigment mass. Thus the differ- 
ence in oil absorption and body imparting property shown by 
various pigments is due to the difference in specific surface or 
particle sub-division. From this it follows that the variation 
or difference in pigments in this respect exists up to satura- 
tion point only: Beyond this point they all become uniform 
in the amount of oil required to bring the mixtures to a cer- 
tain consistency. This fact is important in the comparative 
testing of pigments in liquid paints. The following is illus- 
trative of its application. 

If a series of pigments are ground into pastes on the basis 
of the individual oil absorptions of each, and the same amount 
of thinning mixture is then added to the same weight of each 
dry pigment in its paste form (pigment plus oil required to 
saturate), the resulting mixed paints, barring thickening due 
to any chemical action, will be of practically the same con- 
sistency. 

Considerable information is also obtained by studying the 
condition of the pastes at the oil absorption point. A very 
considerable difference will be noted in the characteristics of 


*It is believed that the oil absorption of a pigment may be reduced by 
compacting. The small particles would then form aggregates and the specific 
surface would be reduced, thus reducing the oil absorption. Similarly, by 
effecting electrical changes in the particles to cause a coalescence or by 
effecting a change in the surface tension of the particles, a reduction in oil 
absorption might be accomplished. 


268 Oil Absorption Tests 


the pastes produced by various pigments. Some pastes will be 
short and tough. Others will be long, stringy and soft. Some 
will have a high gloss. Others will present a dull appear- 
ance. Some of the pastes will be dense, requiring heavy pres- 
sure to flatten them out. Others will be soft and easily spread. 
The amount of oil absorbed does not entirely control these 
factors. In other words, two pigments of practically the same 
oil absorption may yield entirely different types of pastes. 
For example, one may be dense and the other soft. These 
physical characteristics all indicate certain pigment qualities. 


TABLE 46 
Oil Absorption Factors on Some Pigments 
Gardner-Coleman Method 


Low-Oil High-Oil Average 
Pigment. Absorption Absorption Type. 

Type. Type 
Basic Carbonate White Lead........ gs 22.0 ce 
Basic Sulfate White Lead........... 26 32 30 
Zine ONE Le ses 6 te ee eee 47.6 54.1 52 
TAtaROX i xa eG bide oe oe eee 22 28 26 
an Leaded’ Zine. 427.245 seen eee B13 36.5 ae 
Lithopoue 3. ..cc on she oe eee ya Rees . BoD 33 
Asbestine*:;.;.2.4. ts sie k saa eee ae 5O 50 
RAPTYtOS 22045. WS 44 pee eee 13 15 13.5 
Blane Wise. o:4255 4 takes ee ere 23 36 30 
(Ghina Clay's) s0 dss Jove ce eee 41.5 53 > 51 
GYDSUM. @ . Ss ei ee eee 26 eta 33.5 
Siliea: (Crystalline }>.. {3.52 eee 20 . 28 23 
Silica. (Amorphous) 2 io.0, eee ee 30 38 32 
Pele 4. saw spe haa eee . 40 65 60 
Writings 0. sig oct ote eee ee 28 35 32 


The oil absorption point varies with different pigments and 
is influenced by certain conditions. A pigment in its dry state 
consists of individual particles and agglomerates of particles. 
The particle surface and the mass particle surface combine to 
make the absolute surface existing in a given volume of the 
pigment. As the amount of oil required to saturate a certain 
amount of pigment is the amount required to wet the absolute 
particle surface, any influence which tends to change the sur- 
face content (by changing the specifie surface) varies the oil 
absorption point. Two common influences accomplishing such 
change are found in the dispersion effect of certain vehicles, 
and the effect of mixing and grinding pressure. While these 
influences are always present to some degree in all paint mak- 
ing procedure, the basis of the oil absorption factor should be 
the condition of the pigment in its dry form with the elimina- 


Oil Absorption Tests 


269 


Gardner-Coleman Oil Absorption Results 


TABLE 47 


Raw Linseed Oil 


Soya Bean Oil 


Colloidal Condition 


Oil 
aaa Oil Ab Oil Ab 
Ut AD- | Character | “1 4*°” | Character Oil Ab- | Character 
Pees of Paste naa of Paste ee of Paste 
Pipe Oxide 5. .0.::...0.. 54 Smooth. 53 Same as | 56.5 Glossy. 
Glossy. with Smeary. 
Quite Linseed Quite 
long. Oil. rubbery. 
Leaded Zinc 36.8 Soft. 35.5 Same as 39 Quite 
Oxide (35%). with glossy. 
Linseed Smeary. 
Oil Rubbery. 
Slightly 
granular. 
Lithopone (High 3135 Short. oy Same as 38 Fairly 
Oil Absorption). Chalky with glossy. 
Smooth. Linseed Long but 
Oil. not 
tough. 
Slightly 
granular 
in ap- 
pearance 
Lithopone (Low | 25.5 Soft and 23:5 Same as 26 Very soft. 
Oil Absorption). Long. with Runny 
Fair gloss. Linseed and 
Contains Oil smeary. 
large Good 
lumps. gloss. 
Lumpy. 


tion of these influences to as great an extent as may be pos- 
sible. The oil absorption factor of all pigments is changed to 
the same relative degree by the introduction of these influences 
to an equal extent. 

Certain oils and liquids, due to surface tension phenomena 
or to such colloidal conditions as effect absorption or develop- 
ment of great surface, tend to cause either a coalescence of the 
pigment particles into particle agglomerates or by their dis- 
persion effect, to break down the existing agglomerates and 
disperse the particles into an extremely fine state of sub- 
division. Hither of these conditions change the specific sur- 
face of the mass and accordingly change the oil absorption 
point. This variation in oil absorption with different oils is 


270 Oil Absorption Tests 


illustrated by the following table, which gives the oil absorp- 
tion factor of several pigments in linseed oil, in soya bean oil, 
and in a liquid having a relatively high colloidal viscosity but 
with an apparent viscosity approximately the same as the 
other two. 


Selection of Test Liquid.—In view of the results shown in 
the above chart it is important that the oil used for determin- 
ing the oil absorption factor be one that will have the minimum 
effects in causing either a dispersion or coalescence of the pig- 
ment particles. In such a vehicle the pigment tends to form a 
mechanical suspension or mixture only. Thus the degree of 
particle sub-division or agglomeration existing in the dry pig- 
ment is retained to the greatest extent. Of the common and 
available oils, raw linseed oil is the best suited for the pur- 
pose. With most pigments it has but little dispersing or coal- 
escing effect. It is therefore used as the standard vehicle for 
determining the oil absorbing property of a pigment. If, how- 
ever, it is desired to determine the oil absorption factor with 
certain other liquids, the results will be relative to the dispers- 
ing effect of the liquid used. In following the standard pro- 
cedure a well settled Raw Linseed Oil, clear and free from 
foots and having an acid value of from one to three should be 
used. An oil of this kind is readily obtainable and easily kept. 
A variation in the acid value of the oil affects the oil absorp- 
tion point; the amount of oil required increasing with an in- 
crease of the acid number. This difference is due either to a 
greater particle dispersion or to a thickening caused by the 
formation of soaps. It is important, therefore, that in mak- 
ing determinations where very accurate results or close checks 
are desired, that the oil used be always of the same acid value. 


iE fect of Moisture on Test—The moisture contained in the 
pigment, between certain limits, seems to play no important 
part in the determination, since check results may be obtained 
on portions of the same sample of pigment whether air dried, 


oven dried or even slightly moist. Therefore, the ordinary | 


air dried sample of commerce is in a satisfactory condition if 
it does not contain sufficient moisture to cause it to mat to- 
gether or cake. : 


The temperature of the relatively small amount of oil used 
during the operation is not important, because the oil is 1m- 
mediately cooled by coming in contact with the much larger 


ear an 


Oil Absorption Tests 271 


mass of pigment. This statement is made with the assumption 
that the oil is of the temperature prevailing in the ordinary 
laboratory. When, however, the pigment is quite warm, the oil 
absorption is shghtly decreased. This is due to the fact that 
that viscosity of the oil is decreased by rise in temperature 
and consequently the thickness of the. film with which it wets 
the particles would be decreased. However, the difference 
between 70° and 100° Fahrenheit, which is the average range 
of a laboratory, is very slight so that the temperature need 
not be taken into consideration except during extremes in 
either way. 


Principles to be Observed in Test.—The principle of this 
test is that of effecting the wetting of all the ‘‘particle sur- 
face’’ or ‘‘particle agglomerate surface’’ of the pigment mass 
without the application of mixing or grinding pressure. This 
is accomplished by certain oil addition and stirring procedure 
as described herewith. In all stirring operations, care must 
be taken not to cause mixing of the pigment and ‘oil by apply- 
ing pressure, as this factor will tend to vary the results. All 
stirring and mixing should be done very carefully and lightly. 
A finger and wrist motion is all that should be used, allowing 
the forearm to rest quietly. 

When the oil first comes in contact with the pigment, a cor- 
responding amount of particle surface is wetted. The par- 
ticles thus wetted then coalesce or cling together and form 
agglomerates or lumps of paste consisting of oil and pigment. 
These small lumps of paste should be kept distributed through 
the mass by stirring. As the absorption of oil by the mass in- 
creases these lumps will mat together, forming larger lumps 
or balls of paste. With further absorption of oil by the mass, 
these larger lumps or agglomerates of oil and pigment paste 
will coalesce and with most pigments will form one large ball. 
(With a certain few pigments this large ball is not formed; 
the separate smaller lumps remaining separated.) After this 
point is reached a small amount of dry pigment may still be 
left around the bottom and lower parts of the container. This 
pigment is wet by bringing it in contact with the free oil exist- 
ing on the surface of the large ball or lumps of paste. The end 
point of the determination is reached when all of this dry 
pigment has been taken up and wet. This point is indicated 
by the following condition. While any dry unsaturated pig- 


272 Oil Absorption Tests 


ment still remains, the paste will not smear on the glass. At 
the point, however, where all of the pigment particles are wet, 
the paste becomes soft and will smear on the sides and bottom 
of the container.* The balls of paste may then lose their rig- 


idity and tend to flatten out or lose their spherical form. This 


point, which is very sharp, occurs within narrow limits and 
is the end point. The apparatus required and method of test 
are given below. 

Burette.—A standardized burette should preferably be used. 
If not standardized, the determinations should always be made 
by starting with the same burette filled to the zero point. In 
this way possible differences due to variation in the burette 
graduation are largely eliminated. 

Container for Mixing Pigment and Oil.—For this purpose 
a smooth, round bottom jelly glass is very well suited. Those 


having dimensions of approximately 2144 inches diameter at 


top, and 314 inches deep are easily obtainable. Flat bottom 
glasses or those having fluted sides or bottom should not be 
used, as the pigment and paste tend to collect in the crevices, 
making accurate determinations difficult. 


Spatula—A blunt end, 4 inch, stiff blade spatula should be 
used. If the blade is too limber, excessive stirring is required 
and the results are liable to vary. 


Preparation of Sample.—The sample to be tested should 
first be placed in a suitable container (a small wide-mouth 
bottle is adaptable) and well shaken so as to assure the elimi- 
nation of any packed particles or lumps. This is especially 
important if the pigment has been packed in barrels or other- 
wise kept in a manner that is liable to cause it to pack to- 
gether. If excessively moist, the sample should then be air 
dried at room temperature. 


Procedure.—Twenty grams of the pigment are placed in the 


glass. The oil is then run in from the burette, either drop by 
drop or with successive small additions. Either of these 
methods will give check results. If the drop method is used 
the rate of flow at the start should be about one drop per sec- 
ond. If the small addition method is used, quantities of 1% ce. 
should be added. As the absorption of the oil increases, the 


*See Fig. 94. 


ee == 


Oil Absorption Tests 273 


rate of flow or quantity of the additions is decreased. This 
is fully explained later. The oil is run in so as to strike the 
dry pigment in the center. As the oil comes in contact with 
the pigment, the dry pigment that has not been wet should be 
lifted from the outer edge and placed over the oil so as to 
bring all the oil surface in contact with the pigment. This is 
best accomplished either by lifting it up on the spatula and 
dumping it off on the oil, or very lightly throwing it over the 
oil. ae 
When the pigment particles become wet with the oil they 
tend to coalesce and form small lumps of paste. These lumps 
should be kept distributed throughout the mass. This is done 
by lhghtly stirring the mixture of these paste lumps and dry 
pigment in the manner of stirring described above, being care- 
ful not to use pressure in the mixing. If the drop method of oil 
addition is used this stirring should be carried on continuously 
with the operation of bringing the dry pigment in contact with 
the oil surface. If the successive addition method is used this 
stirring should be done after each addition. As the absorption 
of oil progresses these lumps of paste, by taking up more pig- 
ment and matting together, form larger lumps which when 
stirred around form balls. When this point is reached the 
rate and quantity of the oil addition should be very much de- 
creased and only a few drops added at a time. In adding the 
oil at this point it should be allowed to strike on these lumps 
and not on the remaining dry pigment. After each oil addition 
these lumps are lightly stirred around so as to bring the oily 
surface into contact with the remaining dry pigment. | 
With further oil addition and stirring, these balls will with 
most pigments join together and form one large lump, with but 
little dry pigment remaining. With certain pigments, how- 
ever, the lumps or balls of paste do not join together but re- 
main separate and continue to collect more pigment. At this 
point, which is close to the end point, the oil is added very 
carefully, one or two drops at a time. With many pigments 
one drop is all that is necessary to establish the end point. At 
this stage, the oil should be allowed to strike on the surface of 
the lump or lumps. They should then be worked around so as 
to pick up more of the pigment. When all of the remaining 
dry pigment has been picked up and wet, the end point is 
reached. This is indicated as above explained by the paste 
lump becoming much softer and easily spread with the spatula. 


274 Oil Absorption Tests 


When stirred around it smears on the sides and bottom of the 
glass. This end point is very sharp and occurs within narrow 
limits. With most pigments only one or two drops of oil is 
required to change the relatively hard dry lumps which do not 
smear the walls of the container into a fairly soft paste which 
will smear when stirred around. If, when the end point is 
reached, the paste lumps are broken down or spread with the 
spatula, it will be noted that the oil is uniformly distributed 
throughout the mass and no dry pigment remains. 

Different pigments have certain individual characteristics in 
absorbing oil. These must be given consideration, and it is 
sometimes necessary to slightly modify the procedure in order 
to conform with these peculiarities. For example, some pig- 
ments absorb the oil readily and in a uniform manner, while 
others take up the oil slowly. The paste lumps of some are 
smooth and free from hard agglomerates and are easily kept 
uniformly mixed. Others tend to form hard lumps. With such 
it is difficult to keep the mass uniform. When the end point is 
reached with certain pigments, the paste lumps will be quite 
firm. Other pigments will be firm up to the end point and then 
suddenly become very soft; in some instances of semi-paste 
consistency. These differences are largely due to certain 
surface tension relations of the pigment and oil, a discussion — 
of which is outside the scope of this chapter. A little experi- 
ence with the various pigments will enable the operator to 


effect such modifications as will be necessary to conform with 
these conditions. 


Close checks can be obtained on the test made in accordance 
with the procedure explained above. Experienced operators 
rarely vary more than 0.1 ce. in check tests or in tests conduc- 
ted by different operators on the same sample. For ordinary 
purposes a variation of 0.2 ec. is sufficiently close. A variation 
of more than this amount on check tests can only be considered 
as an error in the operation. In testing new pigments or 
where a close determination is desired, two or more check 
tests should be made. A little experience and a consideration 
of the following previously stated precautions is sufficient to 
insure accurate results: 


(a) The pigment must not be moist. 
(b) It should be well shaken before making the test. 


_(¢) It should not be of a temperature lower than 70° or 
higher than 100° F. z 


Oil Absorption Tests 275 


(d) The oil should be well settled and of a standard acid 
value. | | 

(e) The oil should not be added too fast, nor should it be 
added slower than is necessary. 

(f) The mixture should only be stirred enough to keep the 
mass uniform and bring the pigments in contact with the oil. 

(g) Excessive stirring tends to lower the result. 

(h) The stirring should be done lightly and care taken not 
to use pressure or endeavor to mix the pigment and oil by this 
means. 


(1) When nearing the end point, the oil should be added 
slowly and in small amounts (one or two drops at a time). 


FIGuRE 94 
Pigment Mass Just Before Pigment Muss at Point of Satura- 
Point of Saturation. Mass is tion. Mass Loses Its Spherical Form 
Spherical and Does Not Mark and Smears Glass. 


Glass. 


CHAPTER XVII 
TEXTURE OF PIGMENTS 


The property which many pigments exhibit in readily dis- 
persing and becoming finely divided when mixed with a liquid, 
even without grinding, is due to a quality termed ‘‘texture.’’ 
This term is used to designate the structure of the pigment, 
and bears no relation to its fineness. As there has been some 
confusion among paint manufacturers regarding the applica- 
tion of the terms of ‘‘texture’’ and ‘‘fineness,’’ the following 
definitions and discussion are given. A comparison of them 
will serve to show their proper application and import. 


Texture —‘Texture. By extension, the peculiar disposition of the con- 
stituents parts of any body—its make, consistency, etc.; structure in gen- 
eral, as the texture of rocks, the mode of aggregation of the mineral sub- 
stances of which rocks are composed. It relates to the arrangement of their 
parts viewed on a smaller scale than that of their structure. The texture of 
rocks may be compact, earthy, granular, scaly, slaty, ete.” (Century Diction- 
ary.) And the attributes of texture: “Hard, Solid and firm to the touch; 
firm in substance and texture, so as not to be readily altered in shape, pene- 
trated, or divided; so constituted as to resist compressing, penetrating, 
dividing or abrading action; opposed to soft.” (Century Dictionary.) “Soft. 
Yielding readily to pressure ; easily penetrated ; impressible; yielding; opposed 
to hard; easily susceptible of change of form. (Century Dictionary.) 


Pinatas mae Consisting of minute particles, grains, drops, flakes, etc.” 
(Century Dictionary.) And its opposite characteristic, coarse. “Coarse- 
grained, consisting of large particles, fibres or constituent elements.” (Cen- 
tury Dictionary.) 


From the above definitions it is apparent that the terms 
‘coarse’’ and ‘‘fine’’ refer to the extent of the subdivision of 


the particles constituting a mass. They are quality terms and 
are subject to the determination of degree of either property 
by measurement of the size of the particles. 

The terms ‘‘hard’’ and ‘‘soft’’ (which are the attributes of 
texture) are quality terms and relate to the character of the 
mass or of the particles of which it consists. They are in this 
sense relative terms and as such are determined in degree by 
comparison and by such means as will indicate differences 
sharply. Fineness, then, relates to the degree to which the 
particles have been subdivided, and texture to the character 
of the particles, independent of their size. As applied to pig- 
ments, the important properties and the most desirable from 
a general paint-making standpoint are maximum fineness and 
soft texture, although there are certain exceptions to this, such 


Texture of Pigments OBA 


as the use of hard pigments in wood fillers and in small 
amounts in certain mixed paints. 

From this it will be seen that pigments of equal fineness may 
differ greatly in texture of a similar texture may vary in their 
degree of fineness. Closely related to the texture of a pigment 
are, ease of grinding, character of finish, settling and harden- 
ing in the package, and to some extent flowing and spreading 
of the paint. A pigment of soft texture disperses more read- 
ily, grinds more easily, produces a smoother finish, has less 
tendency to settle and harden, and makes a better flowing and 
spreading paint, than one of hard texture. 


The test described herewith for determining the compara- 
tive texture of pigments has been widely used by certain man- 
ufacturers and found valuable as a method for setting stand- 
ards and in investigation work. It is based on the extent to 
which pigments under certain conditions will disperse in a 
liquid having good dispersing properties. The liquid used is 
a mixture of equal parts by volume of blown linseed oil of a 
specific gravity of approximately .945 to .950 and pure turpen- 
tine. This mixture should be of slightly higher viscosity than 
raw linseed oil. If on account of age or storage in open tanks 
the blown oil has become heavy, a further addition of turpen- 
tine should be made so as to bring the mixture to the proper 
consistency. It should be strained through silk or very fine 
cloth before use. 


Apparatus Required—Ground or frosted glass plate about 
one foot square. Several clear glass plates 4” x 4” or 4” x 6”. 
Three-inch glass muller. Artist’s spatula (4” blade). Small 
spatula. 50 cc. beaker. It is important that the small glass 
plates be thoroughly washed with soap and water, and then 
with alcohol so as to remove all dirt and grease from the sur- 
face. If a soft cloth is used for drying the washed glass, it 
should be first washed in alcohol, and dried, so as to free all 
loose particles of lint. 


Method of Making Determination.—12 ce. of the liquid de- 
scribed are used with from one to two grams of pigment. The 
amount of any pigment used depends on its oil absorption. 
With high oil absorbing pigments such as zine oxide, high oil 
absorption lithopone, asbestine, china clay, and similar pig- 
ments, one gram is sufficient. With medium oil absorption 
pigments, such as low oil absorption lithopone, whiting, silica, 


278 Texture of Pigments 

ee nn ORG 
etc., one and one-half grams are used. For pigments of low 
oil absorption, such as basic carbonate or basic sulphate white 
lead, barytes, etc., two grams are used. As the test is only 
qualitative and largely comparative, a closer calculation than 
the above, based on oil absorption, is not important. 

The pigment is mixed to a thin semi-paste on the ground 
glass plate with about lec. of the liquid. This paste is then 
well rubbed out with the muller in three mulling operations 
for one minute each. This is done by mulling the paste con- 
tinually for one minute, then scraping it up to a pile on the 


FIGuRE 95 


Photomicrograph of paint of good texture flowed 
on glass. Note fine particles. 


plate. This operation is carried out for the third time. The 
purpose of this mulling is to break down the particle agglo- 
merates of the pigment and to cause each particle to become 
wet with the liquid. A light pressure in mulling, sufficient to 
thoroughly rub out the paste, is preferable to a heavy grinding 
pressure. 


It has been found that mulling to the extent stated is suffi- 
cient to practically eliminate any variation in results, although 
further mulling, even with more pressure, does not materially 


ee ee ee ee ee ey ee a 


ee ee ae 


Texture of Pigments 279 


affect the results. Between each mulling operation, a few 
drops of the liquid should be added in order to compensate 
for evaporation or thickening condition. 


After the mulling is completed, thin the paste with a further 
amount of the liquid and transfer to the beaker. Add the bal- 
ance of the liquid, and stir thoroughly. Let stand for one or 
two minutes to eliminate the air. Then pour the mixture on a 
clean glass plate, holding the plate in an almost vertical posi- 
tion and pouring the Peat across the upper portion so that it 
will flow down. Place the plate in a vertical position so that 


ae s >i - i 
Bit oiiatlon oe . 


FIGURE 96 


Photomicrograph of paint of poor texture flowed 
on glass. Note coarse particles. 


the excess will drain off. It should be left in this position un- 
til the film is dry. 

In this test the pigment particles of soft texture will become 
so finely divided that they are either collodially dispersed or 
so finely dispersed as not to be visible to the eye. The harder 
particles which have not been finely dispersed show up. As 
the mixture flows down the plate, the smaller particles remain 
at the top in the thinner part of the film while the larger par- 


280 Texture of Pigments 
a 


ticles as well as pieces of lint and dirt flow down to the lower 
part of the plate and can be easily observed in this portion of 
the film. 

~ Interpretation of Results——Some pigments disperse easily 
and to a great extent, while others contain many small and a 


few large particles which do not readily disperse. Others con- 


tain a majority of large particles. A comparison of different 
pigments or different lots of the same pigment will serve to 
show their character in this respect. 

~ Liquids also vary in their dispersing property. Some will 
disperse pigments to a greater extent than others. Certain 
liquids may with certain pigments have the opposite effect— 
that of causing some pigments to agglomerate and form large, 
hard particles. This test may therefore be used to determine 
the relative dispersing properties of paint hquids. For this 
purpose any one pigment may be tested with several liquids 
in the manner described, and comparisons made. 


CHAPTER XVIII 


MISCELLANEOUS PHYSICAL TESTING DEVICES AND 
METHODS 


There is presented below a description of some miscellane- 
ous apparatus and methods of test which have been used to 
advantage in testing various coating materials. 

Testing Printing Effects upon Films.—One of the principal 
advantages of a nitrocellulose lacquer is its property of rapid 
drying. It is difficult, however, to state how soon a laequer is 
sufficiently dry to withstand packing and shipping without 
showing printing. An apparatus used at the Parlin plant of 
the du Pont Company for this purpose is shown herewith, in 
Pip. | 


FIGURE 97 


Print Testing Device. 


It consists of a wooden base on which are mounted two fixed 
standards between which is fastened a bar which can be ad- 
justed to the thickness of the panel to be tested. The remov- 
able levers carrying weights are graduated. 

After a definite drying time the panel is placed on the base; 
any suitable coarse material such as cheesecloth or burlap is 
dampened and laid on the lacquer, and the weight adjusted to 
the desired magnitude. The test is allowed to run for a defi- 
nite length of time, generally about 6 hours at the end of which 
the panel is examined for the print or impression of the cloth. 


282 Miscellaneous Physical Testing Devices 
a ea 

Testing Impact Effects upon Films.—An instrument used at 
the Parlin plant of the du Pont Company for measuring the re- 
sistance to shock of an enamel or lacquer is shown herewith. 
This instrument has apparently proved very satisfactory for 
determining the elasticity or adhesion under the conditions 
of the impact. 


FIGuRE 98 


Impact Testing Machine. 


The apparatus consists of two parallel standards one of 
which carries a scale, and between which is a fixed anvil. 
Resting on this anvil can be seen a panel to be tested. The 
tool for impacting the panel equipped in this ease with a ball 
bearing tip, passes through a fixed rung a few inches above the 
anvil. Above the rung is a movable hammer which may be 
dropped through any desired distance using a suitable weight, 
making various types of impact depending on the position of 
the panel, and the nature of the tool employed. 


Miscellaneous Physical Testing Devices 283 

—$—S —$————— 
The photograph shows a group showing the various tools 
which may be used in getting different types of impact as 
well as a panel which has been tested with the ball bearing 
impactor. It will be noticed that impacts have been made 
from the underside of the panel as well as directly on the 
lacquer. In other words, some of the depressions are concave, 


FIGURE 99 


Impact Testing Device in Operation. 


others convex with respect to the coated side of the panel. 
The concave impacts, i. e. where the impact has been made 
directly on the coating, give, as well as resistance to shock, a 
measure of the adhesion of the enamel; while the convex 
impacts, i. e. those made on the under side of the panel, meas- 


284 Miscellaneous Physical Testing Devices 


ure the elasticity, or the ability of the enamel to stretch around 
the protrusion made by the tool under the conditions of the 
impact. 7 

The resistance to impact is measured quantatively by 
scraping off the loosened enamel with a spatula, and measur- 
ing the diameter of the exposed portion, thus facilitating com- 
parisons between products of different compositions. 


Methods of Tésting—To make an impact test, place the 
panel in the position shown in the photograph, 1. e. resting be- 
tween the anvil and the impacting tool. Raise the hammer 
through the desired distance, usually 20 inches, and release. 
Reverse the panel and follow the same procedure. When sey- 
eral tests have been made, examine as described above. 


Testing the Discoloration of Interior Whites.—The simple 
form of cabinet shown in the illustration was designed for use 
in testing the ‘‘yellowing’’ of interior paints and enamels. It 


| ZZ LLGL DDL DLA MM 

| ‘ TT UIT} Sa i 2 Ls Zs 
| eee hi ies ce i i 
lt Tl 
Hu Ltn, ts = 
LT ili 
2 HA 

Figure 100 
Dark Chamber, i 


Gardner Color Change Cabinet. 


Miscellaneous Physical Testing Devices 285 


is made of galvanized iron with a double walled air space in 
the center. The sides and tops are provided with air ducts 
and holes for thermometric readings. At the bottom of each 
chamber, a shallow pan containing several sheets of blotting 
paper is placed. An ounce and a half of water is added to 
each pan and readily absorbed by the paper. This amount 
is usually sufficient to provide high humidity of the atmos- 
phere in the white chamber for a period of 12 hours and in the 
dark chamber for 30 hours. The entire inner surface of one 
chamber is coated with flat black and the other chamber with 
flat white. The white chamber is furnished with electrical 
connections and a 75-watt blue Daylo Mazda lamp which simu- 
lates ordinary noon daylight. A 10-foot length of insulated 
wire is provided for plugging into any convenient electric 
light socket. When the lamp is lighted, the temperature in 
the white chamber will run from 48° C. (118° F.) to 56° C. 
(132° F.), at various points, whereas the black chamber will! 
show approximately 28° C. (82° F.). 


Application of Black Cabinet.—A series of metal, wood or 
other types of slats are coated with white paint, dried, and 
then exposed in the black cabinet. The warm, humid atmos- 
phere will quickly develop differences in the colors. In two 
days’ time a loss of reflection of about 6 per cent has been no- 
ticed in one type of paint, due to yellowing of the oil content. 
Marked differences in such a short period have also been no- 
ticed in various types of marketed industrial paints and ena- 
mels. In a longer period much more discernible results may 
be noticed. It is believed that these results may be compara- 
ble to what would occur to paints in a very much longer time 
when exposed on factory walls. 


The addition of a small amount (5 per cent) of ammonia 
water to the water used in the pan in this cabinet will greatly 
accelerate the yellowing of the paints. 


A pplication of White Cabinet.—Paints containing pigments 
that are easily fogged by strong sunlight may, after proper ex- 
posure to the bombardment of transmitted and reflected light 
rays, be affected to some slight extent in the white cabinet. 
The paints may be applied to panels and exposed in the eabi- 
net, or the pigment under examination can be rubbed up with 
a normal quantity of the liquid in which it is to be used in 
paint. This may then be spread upon a panel and dried. Half 


286 Miscellaneous Physical Testing Devices 


of the surface may then be covered with black paper. Daily 
examination of the panels, until a difference is noted in the 
covered and uncovered portions, will be instructive. Similar 
tests may be made on organic colors that may be easily af- 
fected by light. It should be remembered, however, that the 
light from a Daylo Mazda lamp is extremely mild as compared 
to that from an ultro-violet arc; the latter giving effects in a 
few minutes that are not obtainable over a long period of 
time by other means. ‘The white cabinet described above may, 
therefore, be of but little use when a quick test for fogging is 
desired. The writer is, however, endeavoring to arrange a 
cabinet with an extra compartment provided with an iron 
are rich in ultra-violet rays. 


Corrosion.—lither cabinet may find some application in de- 
termining the comparative corrosion resistance of metal pan- 
els. The temperature and high humidity should give notice- 
able results. Similarly it may be used for determining the 
rust-inhibitive properties of pigments. In the latter case the 
pigment is mixed to a thin paste with water and applied to a 
small area on a brightly polished steel surface. After expos- 
ure for forty-eight hours, the test plates are removed, the pig- 
ment washed off, and the area formerly covered by the pig- 
ment examined for signs of rusting or etching. 


Testing the Insulating Value of Coated Pipes.—The type of 


a aS 
ane 
Pa 


oy <0 oy <9 
th it~ 


Figure 101 


Moisture Condensing From Atmosphere Upon Surface of Coated and 
Uncoated Pipes. 


P 


Miscellaneous Physical Testing Devices 287 
a 
apparatus used by the writer to determine the insulation value 
of protective coatings upon pipes carrying water and liquids 
of low temperature, is shown in Fig 101. If such pipes are ex- 
posed in warm rooms, beads of water may appear upon the 
surface, due to condensation of moisture from the atmosphere. 
In the illustration, the large container shown is filled with ice 
water which flows down through the two lateral pipes. One 
pipe may be left bare and the other painted. After drying, 
the tests may be applied for a period of 30 minutes to deter- 
mine the relative value of the coatings. 


Testing Paints of High Luminosity to Reduce Refrigeration 
Losses.—During the summer months, surfaces painted in dark 
colors rapidly absorb heat rays and become very hot. When 
white paints are used, the painted surfaces are slow to absorb 
heat rays and consequently will be found many degrees cooler. 
An application of this principle might well be made to con- 
Serve ice and keep refrigerator cars and ships at a tempera- 
ture sufficiently low to preserve perishable foodstuffs for a 
longer period. At the present time, refrigerator cars are usu- 
ally painted an orange color, while refrigerator ships are gen- 
erally painted battleship gray. Both of these colors rapidly 
become warm and transfer their warmth to the compartments. 
Losses in ice and foodstuffs may result. White or hght tints 
of paint should be adopted for both of these carriers. 


In the test apparatus constructed by the writer, a double 
wall effect was obtained by placing a pint container inside a 
quart container. Ground cork (about 1/16 to 1/8 inch in dia- 
meter) was filled in between. The exterior surface of the 
outer container was painted in two-coat work, each with a 
different color. Several containers were thus prepared and 
filled at the same time with a low temperature refrigerating 
liquid. The hquid used was ice water in one instance, and a 
Solution of solid carbon dioxide gas in acetone in another in- 
Stance. The latter had a temperature of -40° C. Closely ecom- 
parable results were obtained with these two liquids. Cracked 
ice was also experimented with, but it was found diffeult to 
obtain uniform temperatures in each can because of the diffi- 
culty of transferring the ice in exactly equal quantities with- 
out loss of temperature. 


After placing the liquids in the inner cans, the covers, which 
were provided with stoppers and thermometers, were adjusted 


288 Miscellaneous Physical Testing Devices 

Se 
and a layer of cork spread over the upper surface. The outer 
containers were then sealed at the top. A row of the vari- 
colored containers was placed out of doors in the sun, and 
thermometric readings made every minute. At the end of 


A RES OS OS Ae ee Be ab a roe LL Lh LD 
wet “A 
7 


edn Oe ans pea 
FIGURE 102 


Inner container for refrigerating liquid. Cork 

air insulation. Outer container painted in 

various colors. Thermometer provided for low 
temperature work. 


thirty minutes, the black cans could not be handled because of 
their high temperature (140° F.)* The white cans could be 
handled comfortably, indicating a much lower temperature. 
Later experiments with white metallic pigment powders indi- 


* On the roof of laboratory at Washington, Aug. 6, 1924. 


Miscellaneous Physical Testing Devices 289 


cated that they do not give as efficient results as a white paint, 
but superior results to most tinted or colored paints. 

The rapid transfer of heat apparently took place from the 
outer can through the layer of ‘cork-and-air’? insulating 
space, and then tough the inner can into the liquid. This 
transfer of heat was very rapid, as is shown by the tempera- 
tures recorded at the end of thirty minutes. It is Ste ae 


AN 


RISE IN TEMPERATURE DEGREES CENTIGRADE 


ee 
Zon 
ales 
Paley) 
oes 
ea) 


TIME IN MINUTES 
i FIGURE 103 


Chart showing comparative rise in temperature of liquid in cans 
painted different colors. 


that much greater differences might be shown at the end of 
six or eight hours time on a freight car in a sunny yard or even 
in transit. Convection might, however, play an important 
feature in the latter instance. 

The results obtained in these tests would suggest the use of 
white or light tints of paints rather than dark colors, on re- 
frigerator cars or ships. 


Testing the Temperature of Colored Building Materials. — 
The temperature of the interior of structures in Summer 
months and of the materials of construction in general, will 
depend to a marked extent on the color of the exterior surface. 
Most uncoated structures will be warmer in the Summer 
months than structures painted in white or light tints. This. 
principle is recognized in tropical countries where structures 
are usually white. Some experiments just completed show 


290 Miscellaneous Physical Testing Devices 

[ji 
the difference in temperature of the air in metal containers 
painted with different colors. The tests also included wood 
panels about 84-inch thick, 4 inches wide and 6 inches long; 
iron panels 34-inch thick, 2 inches wide and 4 inches long. 
Thermometers were inserted deeply into the ends of these pan- 
els. In the metal containers the thermometer readings were 


TEMPERATURES OF SOME BUILDING MATERIALS 


Air in Metal Interior of Interior of 
Structure wood panel iron panel 
Not Painted ows ees ea eee 102°F. 114°F., 126°F. 
Painted ~ “White p24. akiaoatee oe 102 104 106 
Painted “Creams <faien ¢2ecee. 103 110. 110 
Painted.-Aluminuni.,..46445 0084 104 114 114 
Painted - OrdngenJe . eae. ee eee 107 118 118 
Painted Hed Tice sce eee 108 126 122 
Painted: Gray cc. a dssats secs cle aie 110 122 120 
Painted) Bites ear hs oe aia en 108 120 122 
Painted Green ei isa Coe ee 109 124 126 
Painted. Bleek. 36s oak eee ee 114 130 130 
Concrete Slabs ...s.a. tate 108°F. 
Concrete Slab Painted White 102 
Red Brick... anst6ee ee eee 114 
Red Brick Painted White..... 96 


made 14-inch from the bottoms and in the center. All panels 


were exposed on the roof of the laboratory on a day when ~ 


official temperature of the air was 82° F. The highest tem- 
perature recorded in any of the experiments was 130°. On 
one day during the Summer, the temperature of the air was 
106° F., and on that day the black panel registered 140° F. 


The wide difference in temperature of the uncoated and 
eoated red brick is of great importance and would indicate 
the advisability of painting red brick dwellings. The paint- 
ing of such buildings would not only reduce the temperature 
in Summertime, but would probably be of benefit in the Win- 
ter months, because of the possible insulating value of the 
paint in preventing the heat from getting outside. Moreover, 
painted bricks are not as porous as unpainted bricks. Driv- 
ing rain storms cause the absorption of large amounts of water 
in a brick surface. To demonstrate this, tests were made on 
unpainted and painted bricks of the same type. These were 
immersed in water for a period of one hour. The gain in 
weight in water of the two is shown below: 


Miscellaneous Physical Testing Devices 291 


Brick Before Soaking....... 1968 Grams 
itiek iter Soaking ....... 2198 
Begins Water)... 2.405. 230 Grams 
Painted Brick Before Soaking 2022 
Painted Brick After Soaking. 2032 
Perr ater .. 6c... oS. 10 Grams 


Testing Film Thickness as Affected by Speed of Withdrawal. 
When articles to be coated with japan or pigmented enamels 
and similar products are immersed in the coating medium and 
then withdrawn, the thickness of film deposited will vary with 
the speed of withdrawal. Thus, for instance, if the object is 
withdrawn rapidly, a thick film will be applied. As a rule, 
if the object is withdrawn slowly, a thin film will be applied. 


Some preliminary tests to determine the thickness of films 
applied to small sheets of glass withdrawn at different speeds 
are described below. In the experiments, a black baking 
Japan and a green baking enamel were employed. These were 
reduced to various consistencies with two different kinds 
of thinning materials, namely, mineral spirits and painters’ 
naphtha (petroleum benzine). The mineral spirits employed 
met the specifications of the Federal Specifications Board, 
Standard Specification No. 16, U. S. Government Specifica- 
tion for Volatile Mineral Spirits for Thinning Paints (Bureau 
of Standards Circular No. 98). The painters’ naphtha or ben- 
zine employed had the following boiling range: 


EE EP OEAVITG 6. os soc ns a os so cc ee ducacccccs 62° C. 
NS aA SES a a re 106° C. 

0 y Re te rt AP ia beng och oe ni dae ay 
30% ‘ RN ss aetiee eae et ony. wel Ges cx 25°C 
40% a BURR Cea any ne a EGA elie scl e 133° C 
50% ef Rr Ae het ay ets ee eae 2 oe 141° C 

0 re soca ORR A ge 3 Neat NANG 9 De a ae ea 149° C 
70% 2 tere ths i we etic ale Es Sa kk wks 157° C 
80% = MP eel ae rd clomid MOR gk kare con 166° C 
90% Zi eer. oR Ae i tans fee wie 179° C 
ee 5 PE. eke tes oboe ven ceeenc., 206.7° C 


The reductions made were as follows: 
Mineral spirits 


Green baking enamel or benzine 

75 parts by weight 25 parts by weight 
66 TS 66 66 : 83 66 6 66 
60 66 66 66 40 66 66 66 


66 6“ 66 66 6é 6e 
50 50 


292 Miscellaneous Physical Testing Devices 


18.0 
wo el LLL hve 


Ne TT 
SMoataees = 
ate NUT 
sole | NU 
Sool _| NSE 
5 ot | Me 
Sool fea A a eS] 
Soest! | 1 | SEE 
8 ole eX 
yo aoe 
5 eo foam TT 
Se 
st LLL ee 
a 
LLL 
oC LEE 

LEE 
OG ste ae 8. 10 l2 14 16 18 2OSRe ee eoee 


6 
DIPPING TIME IN SECONDS 
90 I8 9 
INCHES PER MINUTE 

| FIGURE 104 


Results On Green Baking Enamel. 


oO) 


The rates of withdrawal were: 
90 inches per minute 
18 66 os 6s 
9 6é 
6 es 
After coating and draining for one hour, the panels were 


baked at 150° C. for 8 hours. Thickness determinations were 
then made with an Ames micrometer which is calibrated in 


Miscellaneous Physical Testing Devices 293 


1/100 of amillimeter. The panels were of glass, 3 inches wide 
and 8 inches in length. Lines were drawn 34”, 114”, and 21,” 
from the side after coating. Starting one inch from the bot- 
tom of each line, the thickness was measured every successive 
inch to the top of the panel. The average of these was taken 
as the average thickness of the film. The results are plotted 
in Fig. 104. | | 


Volume and Weight Cup.—F or determining the weight of a 
gallon of paint, many laboratories use a 100 ce. flask or brass 
eup. This laboratory has found it most convenient to use the 


il 
=, 
7 rr9s 


FIGURE 105 


latter. One was made with a section of a brass tube, threaded 
at the end, and fitted with a removable threaded bottom, and 
a ground glass cover. The removable bottom makes it easy 
to clean the apparatus. The ground glass cover permits ac- 
curate filling, being used to level off the excess material. The 


294 Miscellaneous Physical Testing Devices 


net weight of the contents divided by 100 gives the specific 
gravity of the paint. Since the specific gravity of water is 1, 
and one gallon of water weighs 8.33 lbs., the weight of a gallon 
of the material under consideration is 8.33 times the specific 
gravity of the product. Thus, for example, a paint was weighed 
and found to weigh 222. grams, which divided by 100 gives a 
figure of 2.22 specific gravity. This specific gravity, namely, 
2.22 multiplied by 8.33 equals 1814, or the weight per gallon of 
the paint. 

If one of these is made up to contain one gill of liquid in- 
stead of 100 ce. of liquid, the weight of the paint in grams 
would be multiplied by 0.0705 to give the pounds per gallon, 
and by 0.00845 to give the specific gravity. 


Panel Racks for Baking Tests.—At times it is necessary to 
run a large number of baking tests on coated panels which are 


a en a SS a ae en ee : 
SRR OR 
SSS eS SSS: Ath EOI SE BENE 


een 


SR Ce EE ASR 


ea PE ER ER TER a ee 
= Se aN y SR SRC UU 
RANT OO . Poo a A a A SS a eee 

rer SS, SE, SE, WG, E.G, WE, ,G. 
eae ere Serene re rere wen icone ceca ay 


a SN RGA GASA EA SRE eR Ree eR ee 


q RES. GS SR VR OE Spoke i RR ES SR, GRR. CRG “in TE 
CAQAY RES SR SSS SSS SEES SSS 


SSS RRS TT 


\ SS SS enn ese 
SEAVER SEROUS GER, SEAS OU SUDHA, SUA SUAS 'SHA.UR,'SUNLEL.TUEL.TOnOm tone 


Jy SSS SSS SSS SSS 
SRR CP, GE, EO, NA “Hee were Ue. Se, SR 


=e 
[SSSA SSSA, SUR SSO SO WH, VOR SUN'S 'VU Wn, WON, Wana Wann UU "Oun, wun.ouneaneanea oes 


FIGURE 106 
Rack for Panels to be Baked for Kauri Gum Reduction Test. 


to be bent to determine the kauri reduction of the finish. This 
laboratory has found that a set of shelves made of quarter- 
inch mesh wire cloth is very convenient for that purpose. The 
construction of these shelves is shown in the illustration. Fig. 
106. The shelf shown will hold 24 panels. It is placed in a 


a a 


Miscellaneous Physical Testing Devices 295 


hot water oven wherein the temperature is quite uniform 
throughout. ‘The panels are baked for 5 hours, as given 
in the specifications for this test. They are then removed, 
cooled, and bent over a mandril, and examined. 


A Rack for Draining Panels.—In coating small tin panels 
in the laboratory with varnishes for the determination of 
drying time, and hot and cold water tests, it is desirable to 
have some sort of drainage pan where the excess material will 
drain off without smearing the laboratory tables. This labo- 
ratory has constructed a rack which is shown in Fig. 107. The 
size of the pan is 6x18x2 inches. Supported by the sides of 
the pan are four small racks in which the coated panels are 
placed, leaning against wire frames or supports. As the ex- 
cess material drains off the panels, it drips down into the bot- 
tom of the pan through openings. By the use of this pan, 


FIGURE 107 


Drip Pan for Drying Panels. 


the panels can be all kept in one place of fairly constant 
temperature. If desired, the pan with a set of coated panels 
may be carried to any room where constant temperature or 
humidity prevails. 


Brush Cleaning Device.—A simple type of brush cleaning 
device is shown in the illustration below. It consists of a 
metal pan over which is stretched quarter-inch mesh wire. 
Brushes may be given a rapid preliminary ‘‘wiping off’’ upon 


296 Miscellaneous Physical Testing Devices 


this apparatus. It has been found quite useful in the paint 
testing room. 


Wat 
Stas 


RATS OS 
\, LS 


FIGgurRE 108 


Brush Wiping Device. 


Papers on Physical Testing.—The following list of techni- 
cal papers relating to the physical testing of paint and varnish 
products is submitted for those who care to make a complete 
study of the subject. 


Optical Properties and Theory of Color of Pigments and Paints—H. BE. 
Merwin. Proc. Amer. Soc. Test. Mater. XVII—Part II, 494. 

Determination of Absolute Viscosity by the Saybolt Universal and Engler 
Viscosimeters—Winslow H. Herschel. J] bid., 551. 

The Standard Saybolt Universal Viscosimeter—Winslow H. Herschel. 
Ibid., XVIII—Part II, 363. 

The Variable Pressure Method for the Measurement of Viscosity—E. C. 
Bingham. Jbid., 373. 


Miscellaneous Physical Testing Devices 297 


Paint, a Plastic Material and aa a Viscous Liquid: the Measurement of 
its Mobility and Yield Value—E. C, Bingham and Henry Green. Jbid., XIX— 
Part II, 640. 

An Instrument for Measuring the Hiding Power of Paints—R. L. Hallett. 
Ibid., XX—Part II, 426. 

a New Colorimeter for White Pigments and Some Results Obtained by 
Its Use—A. H. Pfund. Jbid., 440. 

Further Development of the Plastometer and its Practical Application 
to Research and Routine Problems—H. Green. Jbid., 451. 

Stress-Strain Measurements on Films of Drying Oils, Paints and Var- 
nishes—H. A. Nelson. Jbid., XXI, 1111. 

The Use of Secondary Reference Standards in Process Problems of Color 
Measurement—H. S. Busby. Jbid., 1139. 

Relation of Yield Value and Mobility of Paints to Their so-called Painting 
Consistency—J. EH. Booge, E. C. Bingham, and H. D. Bruce. Jbid., XXII. 

Some Physical Properties of Paints—P. H. Walker and J. G. Thompson. 
Ibid., XXII. 

Accelerated Weathering of Paints on Wood and Metal Surfaces—Harley 
A, Nelson. Jbid., XXII—Part II, 485. 

An Analysis and Comparison of Systems of Color Measurement and Some 
Notes on Interchangeability in Color Measurement—H. S. Busby. Jbid., XXII. 

An Application of the Pfund Colorimeter.to the Determination of Tinting 
Strength—J. A. Calbeck. Jbid., XXII. a 

Hiding Power of Paints—R. L. Hallett. Jbid.. XXII. Jbid., X XVI, 538. 

The Study of Nitrocellulose Lacquers by the Stress-strain Method—G. W. 
Rundle and W. C. Norris. Jbid., XX VI—Part II, 546. 

Mechanical Testing and Recording of the Drying of Paints and Var- 
nishes—John Mc. Sanderson. Jbid., XXVI—Part II, 556. 

Accelerated Weathering: Further Development of Apparatus and Exposure 
Cycles—H. A. Nelson, F. C. Schmutz and D. L. Gamble. Jbid.,. XXVI—Part 
IT, 563. 

Further Studies of the Physical Properties of Drving-Oil. Paint and Var- 
nish Films—H. A. Nelson and G. W. Rundle. Jbid., XXIII—Part IT, 356. 

Some Optical Properties of White Paint Pigments in the Ultra-violet Spec- 
trum—A. H. Pfund. J/bid., XXIII—Part II, 369. 

The Effect of Certain Paint Films on Ultra-violet: Light—R. L. Hallett. 
Ibid., XXITI—Part II, 379. 

Color—G. W. Thompson. Jbid., XXIII—Part IT, 396. 

Symposium on Consistency. Jbid., XXIII—Part II, 482. 

Further Study of Accelerated Weathering Effect of Variations in Exposure 
Cycle Combinations on Common Types of Varnishes—H. A. Nelson and F. C. 
Schmutz. Jbid.. XX1IV—Part II, 920. 

A Relative Method for Determining Particle Size of Pigments—G. Be Ac 
Stutz and A. H. Pfund. Ind. and Eng. Chem. 19, 51. (1927.) 

The Relation of Yield Value to Particle Size—Henry Green and George 
S. Haslam. Ind. and Eng. Chem. 19, 53. (1927.) 

Particle Size and Distribution by Sedimentation Method—J. H. Calbeck 
and H. R. Harner. Ind. and Eng. Chem. 19, 58. (1927.) 

The Testing of Paint Pigments for Transparency to Ultra-violet Radia- 
tion—G. F. A. Stutz, Jour. Frank. Inst. 203, p. 89. (1926.) 

A Photometric Method for Measuring the Hiding Power of Paints—H. D. 
Bruce. Tech. Paper of the U. S. Bureau of Standards No. 306. 

Reflection Curve in Color Specification—F. P. Ingalls. J. W. Masury & Son, 
‘Brooklyn, N. Y. Paint, Oil and Chemical Review, October 21, 1926. 

Report of Sub-Committee XVIII on Physical Properties of Paint—F. P. 
Ingalls and M. Rea Paul. Paint Manufacturers’ Association of the U. 8S. 
Special Circular, Scientific Section, Educational Bureau, September, 1926. 

Color Measurement: A Method Giving Direct Reading of Color Inde- 
pendent of Color Vision of the Observer—Carl W. Keuffel, Keuffel & Esser Co. 
Paint, Oil and Chem. Review, Vol. 82. No. 5, July 29, 1926. 

Notes on Color Measurement— Carl W. Keuffel, Keuffel & Esser Co. Official 
“a Federation of Paint and Varnish Production Clubs, Vol. 47, Janu- 
ary 


298 Conversion Tables 


Conversion Tables 


Note.—The figures in bold-face type refer to the quantity 
which it is desired to convert from one system to the other 
system. If converting from the system in the right-hand 
column, the equivalent in the other system will be found in 
the left-hand column, while if converting from the system in 
the left-hand column, the equivalent in the other system will 
be found in the right-hand column. For example, 1 inch = 
2.040 em. and 1 em. = 0.3937 inches. 


Cm. Inches Inch 
2.540 1 0.3937 1000 Microns 
5.080 2 0.7874 0.03937 1 25.4 
7.620 3 1.1811 _ 0.07874 2 50.8 
10.160 4 1.5748 0.11811 3 76.2 
12.700 5 1.9685 0.15748 4 101.6 
15.240 6 2.3622 0.19685 5 127.0 
17.780 y | 2.7559 0.23622 6 152.4 
20.320 8 3.1496 0.27559 | 177.8 
22.860 9 3.5433 0.31496 8 203.2 
25.400 10 3.937 0.35433 9 228.6 
27.940 11 4.724 0.3937 10 254.0 
30.480 12 5.512 
Ounces Grams 0S in: C. C. 
0.03527 ah 28.350 0.06102 1 16.387 
0.07055 Pe 56.699 0.12204 2 32.774 
0.10582 3 85.049 0.18306 3 49.161 
0.14110 4 113.398 0.24408 4 65.548 
0.17637 5 141.748 0.30510 5 81.935 
0.21161 6 170.097 0.36612 6 98.322 
0.24692 4 198.447 0.42714 q 114.709 
0.28219 8 226.796 0.48816 8 131.096 
0.31747 9 255.146 0.54918 9 147.483 
0.35274 10 283.50 0.61023 10 163.872 
0.38801 11 311.85 
0.42328 12 340.20 
0.45855 13 368.55 
0.493882 14 396.90 
0.52909 15 425 25 
0.56430 16 453.60 
Pints Liters Gallons Liters 
2A18 1 0.47317 0.2642 1 3.785 
4.226 2 0.94634 0.5283 2 rRiyel 
6.339 3 1.41951 0.7925 3 11.356 
8.452 4 1.89268 1.0567 4 15.141 
10.565 5 2.36585 1.3209 5 18.927 
12.678 6 2.83902 1.5850 6 Pa te B 
14.791 7 3.31219 1.8492 y | 26.497 
16.904 8 3.78536 2.1134 8 30.262 
19.017 9 4.25853 2OiG 9 34.068 
21.134 10 Apa Len 2.6417 10 37.853 


eg 


Ce ae : 
bey 2 poll Sart ey Ral, 4 
a eae hh 


Conversion Tables 299 


sq. in. Cm?, 

0.1550 1 6.452 

0.3100 2 12.903 

046003. ~-°719.355 

0.6200 4 25.806 

0.7750 5 32.258 

0.9300 6 38.710 

1.0845 7 45.161 

TiZoue~ 82 01.615 

1.3949 9 58.064 

1.5499 10 64.516 

TEMPERATURE 
C. F. C. F. cot  ghs Ge F. 
—17.8 Oeeaeioc.co 38° 100.4| 24.4 76 168.8)110 230 446 
—17.2 T 38-8| 3.89 39 102.2) 25.0 Tie 110.6116 240 464 
—16.7 2 35.6) 4.44 40 104.0) 25.6 78 172.4121 250 482 
—16.1 Brat.4\°>.00 41 ~ 105.8) 26.1 79 = 174.2|127 260 500 
—15.6 Beeede.2ib.06.° 42. 107.6} 26.7 80 176.0/132 270 518 
—15.0 Seas 06.11 43 . 109.4) 27.2 81 177.8/138 280 536 
—14.4 Weepae.s) 0.07, 44. 111.2) 27.8 82 179.6143 290 554 
—13.9 fees. Cl 1.22 45° 113.0) 28.3 83 181.4/149 300 Biz 
—13.3 8 46.4) 7.78 46 114.8) 28.9 84 183.2/154 310 590 
—12.8 Gee4as.c| S.00 47 116.6) 29.4 85 185.0/160 320 608 
—12.2 10 50.0) 8.89 48 118.4} 30.0 86 186.8/166 330 626 
—11.7 Bigpor.5) 9.44 49 120.2) 30.6 87 188.6)171 340 644 
—11.1 12 58.6/10.0 50 = 122.0} 31.1 88 190.4|177 350 662 
—10.6 13. 55.4/10.6 Bite 23.3) Olt 89 192.2/182 360 680 
—10.0 04 57.2111. 52 125.6/'32.2 90 194.0)188 370 698 
9.445 15 59.0/11.7 540! 127 A|- 32:8 91  195.8])193 380 716 
6.59. 16° 60.8/12.2 54 129.2) 33.3 92 197.6/199 390 734 
— 6.59 17 62.6/12.8 Sho 151.0) 33.9 93 199.4|204 400 752 
7.15 18> .64.4/13.3 56 =. 1182.8} 34.4 94 201.2/210 410 770 
s=722 19 66.2/13.9 57 «134.6. 35.0 95 203.0/216 420 788 
== 6.67 20 68.0/14.4 58 1386.4) 35.6 96 204.8/221 430 806 
== 0.11. 21 69.8/15.0 59> 2138.2) 36.1 97 206.6|227 440 824 
98-56. 22)! 71.6/15.6 60 140.0) 36.7 98 208.4/232 450 842 
== p.00 23  73.4|16.1 61 141.8} 37.2 99 210.2/238 460 860 
= 444° 24° 75.2/16.7 62 148.6) 37.8 100 212.0)2438 470 878 
epee 25° 77.0117.2 63 145.4) 43 110 2380 |249 480 896 
= 8.06 26 78.8/17.8 64 147.2) 49 120 248 |254 490 914 
ite 27. 80,6118.3 65 149.0] 54 130 266 |260 500 932 
=—2.22. 28 82.4/18.9 66 150.8] 60 140 284 |266 510 950 
e—1i-01 29  84,2/19.4 67 152.6} 66 150 302 |271 520 968 
ott. 30. 86.0/20.0 68 154.4] 71 160 320 (277 530 986 
— 0.56 31 87.8/20.6 69 156.2] 77 170, 3381282 540 1004 
0 32° 89.6/21.1 70 =158.0} 82 180 356 |288 550 1022 
Woo as 91.4/21.7 71 = 159.8) 88 190 374 |293 560 1040 
eb 34.198 2122 2 T2- 21.61 -61.938 200 392 |299 570 1058 
1.67 35 95.0/22.8 73 163.4] 99 210 410 |304 580 1076 
2.22 36 96.8/23.3 74 165.2/100 WAZ Als 1310 590 1094 
2.78 37 98.6/23.9 75 167.0}104 220 428 /|316 600 1112 


CHAPTER XIX 


TESTING WHITE OPAQUE PIGMENTS FOR SOME PHYSICAL 
PROPERTIES (ROUTINE METHODS) 


Color.*—Approximately 5 grams of the sample shall be 
thoroughly mixed with the smallest quantity of bleached lin- 
seed oil that will produce a smooth paste. This paste shall 
be spread on a palette of colorless plate-glass in a smooth and 
even layer, that will not transmit light and is at least 1 inch 
by 3 inches in area. 

An equal amount of the standard (or each of the standards) 
shall be prepared in the same way, care being taken to bring 
the paste to the same consistency as the sample being tested. 
This paste shall be spread in a similar manner on the palette 
beside the sample, touching it, and the two compared in dif- 
fused daylight. In doing so, the palette shall be titled so that 
the light will strike the surface of the pastes at different 
angles and the under surfaces shall also be observed through 
the glass. 3 

In doubtful cases, only the sample and one standard may be 
spread on the palette at the same time, and their edges must 
touch. paaye 

To be on-grade, the sample must be as white as the standard. 


Brightness.*—Five grams of the sample and 1.20 grams of 
bleached linseed oil shall be mixed to a smooth, uniform paste. 
The oil used may be determined by dropping from a point 
which has been standardized by counting the number of drops 
necessary to weigh 1.20 grams. The dropping shall be at a 
rate not greater than 70 drops per minute. All the sample and 
all the oil must be thoroughly incorporated. This paste shall 
be spread on a palette of colorless paste-glass in a smooth and 
even layer that will not transmit light and is at least 1 inch 
by 3 inches in area. 

When the nature of the pigment requires more oil than 
above noted, more shall be used but comparisons shall be made 
only between samples which have a like oil-vehicle ratio. 

An equal amount of the standard shall be prepared in the 
same way. This paste shall be spread in a similar manner on 


* Palmerton Laboratory Method. 


Testing White Opaque Pigments 301 


the palette beside the sample, touching it, and the two com- 
pared by observing in diffused daylight the two samples by 
looking through the glass. 
In doubtful cases, only the sample and one standard may be 
spread on the palette at the same time, and their edges must 
touch. | 

To be on-grade, the sample must be equal to or better than 
the standard in brightness or brilliancy. 


Smoothness and Freedom from Specks.—Approximately 5 
grams of the sample shall be thoroughly mixed with the small- 
est quantity of bleached linseed oil that will produce a smooth 
paste. This paste shall be spread on a palette of colorless 
plate-glass in a smooth and even layer that will not transmit 
light and is at least 1 inch by 3 inches in area. 

An equal amount of the standard shall be prepared in the 
same way, care being taken to bring the paste to the same 
consistency as the sample being tested. This paste shall be 
spread in a similar manner on the palette beside the sample, 
touching it, and the two compared in diffused daylight. In 
doing so, the palette shall be tilted so that the light will strike 
the surface of the pastes at different angles. 


In doubtful cases, only the sample and one standard may be 
spread on the palette at the same time, and their edges must 
touch. 7 

To be on-grade, the sample must contain no more granular 
or foreign matter than the standard. This is to be determined 
by the feel under the knife and the amount of noise made in 
rubbing down and by observation of the surfaces after the 
pastes have been spread on the palette. 


Tinting Strength.—F ive grams of the sample, 0.5 grams of 
ultramarine blue and 1.20 grams of bleached linseed oil shall 
be mixed to a smooth, uniform paste of uniform color through- 
out. ‘The oil used may be determined by dropping from a 
point which has been standardized by counting the number 
of drops necessary to weigh 1.20 grams. The dropping shall 
be at a rate not greater than 70 drops per minute. The mixing 
shall be done by rubbing lightly with a spatula whose blade 
is not over 5 inches long. All the sample, blue and oil must 
be thoroughly incorporated. This paste shall be spread on 
a palette of colorless plate-glass in a layer that will not trans- 
mit light. 


302 Testing White Opaque Pigments 


The standard shall be prepared in the same way and spread 
in a similar manner on the palette beside the sample, touching 
it. : 

Another standard paste shall be prepared by mixing 9.5 
grams of the standard, 0.5 grams of ultramarine blue and 1.82 
grams of bleached linseed oil in the same way and spread in a 
similar manner on the palette beside the sample, touching it. 

In doubtful cases, only the sample and the two standards 
may be spread on the palette at the same time and the sample 
must be in contact with both standards at the edges. 7 

To be on-grade, the sample must not be darker than the 
first standard and not lighter than the second standard when 
observed through the glass. 


Palmerton Test for Settling of White Pigments in Water.— 
This test shall be made in a flat-bottomed glass tube of 11/16 
inch diameter, 6 inches height and uniform bore. ‘T'wenty- 
seven cc. of water should fill it to a height of 434 inches with 
an allowable plus or minus variation of 1/16 inch. 

Five grams of the sample shall be put into the tube after 
the latter is half filled with water. The product and water 
shall be well mixed with a piece of wire about 14 or 12 gauge 
and the tube filled with water to a height of 484 inches. The 
wire is to be removed and washed off in the process of adding 
this water. ‘The tube shall then be shaken vigorously 80 times, 
the thumb being held over the opening in the top. After shak- 
ing, it shall be placed in a rack so that it stands vertically and 
the height of the column of the product measured at the end of 
1, 2, 3 and 24 hours. 

An equal amount of the standard shall be treated in the 
same way. 

To be on-grade, the height of column of the sample must be 
within 10 per cent plus or minus of the height of column of 
the standard at the end of 24 hours. 


Croll Method for Grading Tinting Strength of White Pig- 
ments.—Weigh from one to five grams of the official sample 
of white pigment and for each gram of white pigment, weigh 
twenty milligrams of C. P. Chrome Green. Transfer to a 
clean, smooth glass or stone plate and add a measured amount 
of Refined Linseed Oil in sufficient quantity to produce a stiff 
paste, when oil and pigment are thoroughly mixed with a flat 
glass muller or with steel spatula. After thoroughly mixing 


Testing White Opaque Pigments 303 


to a stiff paste, add several more drops of Refined Oil and 
mix thoroughly to a smooth paste, which can be readily spread 
on a glass plate in a liberal ‘‘smear.’’ Treat standard sample 
and shipment sample identically alike in this test; that is, use 
the same equipment, size of sample and amount of oil, and 
spread standard sample on a palette in a smooth ‘“smear,”’ 
sufficiently thick to cut off transmitting light. Have standard 
‘‘smear’’ and shipment sample spread out side by side in 
actual contact on glass palette. In grading for tinting 
strength, examine the sample in bright diffused day light (not 
direct sunlight) and accept shipment for tinting strength if 
the shipment sample is as light or lighter in color than the 
standard sample. If the standard sample is lighter in color 
than the shipment sample, the material does not meet the 
specification. | 


TINTING STRENGTH (Barton Method) * 


Preparation of Special Lampblack.—Mix thoroughly by 
milling in a dry state in a porcelain Jar mill 6 parts precipi- 
tated calcium carbonate with 1 part lampblack. 
___ General Method.—Mix the sample and the indicated amount 

of tinting pigment with refined linseed oil by rubbing for three 
minutes with a spatula on a glass plate, using such a quantity 
of oil as required to make a stiff plastic paste which adheres 
well to the glass and works easily without breaking. Then 
add enough more oil to make a mixture containing 80 to 90 
per cent by volume of oil, and rub for two minutes. 

Compare the tinting effect with that of a standard tint, 
made by similarly mixing a standard pigment and tinting pig- 
ment with oil to paste form and then reducing to 80 to 90 per 
cent oil by volume. The tinting strengths are practically 


proportional to the amounts of black required to give identical 
tints. 


Determination of Tinting Strength of Titanium Oxide— 
Weigh one gram of Standard Titanox (labeled ‘‘Titanox Tint- 
ing Strength Standard, Niagara Falls, August 7, 1920 Pint 
ing Strength 350’) and .1225 gram of Special Lampblack 
onto an 8’’x8’’ ground glass plate. Add .25 gram (12 drops 
from special burette) of refined linseed oil, and mix for three 


*L. E. Barton, Titanium Pigment Co., Niagara Falls, N. Y. 


304 Testing White Opaque Pigments 


minutes with a flexible spatula. Make a further addition of , 
1.25 grams of oil (60 drops from special burette) and mix for 
two minutes longer. The standard, thus prepared, has a tint- 
ing strength of 350 as compared to a Standard White Lead 


taken as 100. 

The sample of Titanium Oxide to be compared with the 
Titanox is prepared by similarly mixing one gram of pigment 
and the estimated quantity of Special Lampblack (usually 
about .35 gram, corresponding to 1000 tinting strength) with 
88 gram (42 drops from special burette) of refined linseed 
oil and then reducing the resulting paste by the further addi- 
tion of .77 gram (37 drops from special burette) of oil. 

The sample is now compared with the Standard by placing 
portions of the paint side by side and in contact with each 
other on a microscope slide. The samples are placed upon the 
slide by allowing one drop of each to flow from the spatula 
and fall upon the slide so that the drops will flow together. 
This method of applying the sample gives a uniform spread 
which is judged by turning the slide over and viewing through 
the glass. | 

If the sample is found to be of lighter tint than that of the 
Standard, add a greater weight of Special Lampblack to a 
new sample. If it is darker, add a lesser weight of Lampblack 
until the tint matches that of the Standard. Always prepare 
a fresh sample for each trial, mixing in the regular way. 


Determination of Tinting Strength of Titanox and “*C’™* 
Pigments.—The determination of tinting strength of Titanox 
and ‘‘C’’? Pigments is made as described for Titanium Oxide, 
except that the oil additions are as shown in the following 
tabulation: 


1st Oil Eq. Drops 2nd Oil Eq. Drops 
Addition from Spec. Addition. from Spec. Total Oil 


grams Burette grams Burette grams 
Titanium Oxide... =. 88 42 ef if 4 37 1.65 
Titanexe oa. as Ce ae 145 12 1.25 GOs, 1.50 
CP SPIO Men Sie ae 4 16 1.66 79 2.00 


* Calcium Sulfate Base Titanox. 


CHAPTER XX 


TESTING COLORS FOR TONE AND STRENGTH 


Generally speaking pigment colors are bought on physical 
tests rather than chemical analysis. While it is true that the 
knowledge of the exact chemical composition of a color may be 
desirable for certain uses nevertheless the value and suit- 
ability of colors for most purposes can be quickly determined 
by physical tests for overtone and strength, and while making 
these tests, the relative oil absorption, texture, etc., can be 
noted. Suggestions made by A. F. Brown are included below. 


In testing for overtone and strength it is absolutely essen- 
tial that certain fundamental principles be observed, other- 
wise, the tests of two given samples will be misleading. The 
common practice of weighing roughly a given amount of color, 
then adding a certain number of drops of oil and rubbing an 
indefinite length of time with a spatula is likely to result in 
erroneous conclusions. Not only is it necessary that the dry 
color be accurately weighed, but the vehicle should also be 
weighed. Two colors ground in different vehicles should never 
be compared, as different vehicles produce different effects 
with the same color. Sufficient vehicle should always be used 
so that when the color has been rubbed and applied to a strip 
of glass, or tin, the surface’ has a high gloss. In comparing 
the overtones of two colors, if it so happens that one sample 
has higher oil absorption than the other, sufficient additional 
oil should be used with the color having the higher oil absorp- 
tion to produce a paste of about the same consistency, other- 
wise the comparison will be misleading. 


The amount of dry color used in making tests depends upon 
the type of color and the oil absorption. For C. P. Blues and 
C. P. Para and Toluidine Toners 0.5 grams of color is suffi- 
cient, while for C. P. Chrome Greens, C. P. Chrome Yellows, C. 
P. Oranges and all reduced colors, one gram of dry color is 
not too much. The proper amount of vehicle is dependent 
upon the oil absorption and the type of vehicle used. Experi- 
ence has shown that where colors are to be used for certain 
purposes such as enamels, tests are more comparable to fac- 
tory practice if rubbed in a viscous non-volatile medium such 
as a polymerized linseed oil about the consistency of 00 htho 


306 Testing Colors for Tone and Strength 


varnish, instead of raw or refined linseed oil. Ina general way 
the proper proportion of dry color to vehicle is as follows: 


TABLE 48 


Polymerized Linseed Oil 
Raw Linseed Oil (00 litho varnish ) 
Gram color Gram oil Gram color Gram oil 


Cte Tron. Biies cc agutes eee ao i acy 6 
CAP Para: Toner, vee cae are eae ma) 8 b 8 
GUE -Toluidine yponet ye. .-wa es oo 6 na) 8 
C.P. Chrome Green Light..... 1.0 i 1.0 3 
C.P. Chrome Green Medium.... 1.0 6 1.0 + 
C.P. Chrome Green Deep...... LO or 1.0 5 
iP. Chrome Yellow. ick ees as 1.0 4 1.0 4 
C.P Chrome -Orangesivignc ss seu 1.0 oe 1.0 3 
teduced Chrome Greens....... 1.0 “ou 1.0 3 


In weighing, it is desirable to use balanced watch glasses 
counterbalancing the sample against the standard with which 
it is to be compared; the dry colors being first weighed and 
then the vehicle which is placed shghtly away from the color. 
With a little care, no trouble will be had in transferring the 
mass to the rubbing slab. Some operators prefer to add the 
oil from a burette, each drop of raw oil being assigned a defi- 
nite weight. Bodied oils, however, could not be accurately 
weighed by such a method. The Brown burette (see page 259) 
for use in oil absorptions is suitable for delivering raw linseed 
oil in exact amounts. 


The materials should be very carefully transferred to the 
rubbing slab. Plate glass about 24 inchs by 24 inches that has 
been lightly sandblasted (such as can now be obtained from 
any chemical glassware supply house) serves very well as a 
rubbing slab, and a glass muller with a 214 inch face is about 
the right size. The color and vehicle are first mixed with a 
spatula until there are no dry particles of color, then the re- 
sultant paste rubbed with the glass muller a definite number 
of times, care being taken to exert the same pressure on both 
samples so that the relative development will be exactly the 
same. 


The number of times a color should be rubbed depends upon 
the type of color and the actual factory practice as regards 
development. In some factories colors are well ground, but in 
many ostensibly efficient plants it is surprising how little at- 
tention is given to securing the maximum money value by 
complete development. In a general way the number of 


Testing Colors for Tone and Strength 307 


‘rubs’? necessary to secure development equivalent to aver- 
age factory practice is as follows: 


TOT IES. 6. oc ens ce ete te eect e serene 300 times 
Mt ara PONCTS. 6. oc nc epee sete tener eee e ns 300 times 
Were oliiminie “TONCTS. 2. sew ee ee ee ee eens 300 times 
@, P. Chrome Greens... 1... - cece cece ese eeees 150: times 
er wohrome YellOwWS.......2.0.0ssccc ces eceeees 50 times 
Reduced Colors, all kindS.............eseeeeeeees 50 times 


rE Ss sale ts ale igisle nob ose cee Fess oss 200 times 


In rubbing, the muller should traverse a space about three 
‘nehes wide and twelve inches long, the operator pushing the 
muller up one side and down the other side of this strip so that 
all the color particles receive the same amount of attrition 
every rub. By one rub is meant one complete movement up 
and down. In testing a color which requires twenty-five rubs 
the color should be scraped up after fifteen rubs and then 
rubbed another ten times; when testing a color requiring more 
than twenty-five rubs the color should be scraped up with a 
spatula after each twenty-five rubs. After the rubbing 1s 
completed the comparison for overtone should be made by ap- 
plying liberal portions of each color to glass.or tin in juxta- 
position. The larger daub of color the better, but in any event 
each daub should not be smaller than a half-dollar and they 
should be placed in juxtaposition, care being taken that the 
edges just touch but do not overlap and that there is a well de- 
- fined line of demarcation. After being so placed and before 
comparing, a wide spatula should be lightly drawn over both 
at the same time to produce a color surface that will be smooth 
and free from ridges. In comparing for overtone, the colors 
should not be examined through the glass. For this reason 
strips of tin are preferable to glass as it effectively prevents 
this practice. If the colors are to be used for inks, this test 
may be made upon bond paper. Observation of the stained 
paper when held to the light will show whether the color is 
clear, bright or muddy. 

For making strength tests, it is well to have a stock paste 
of zinc oxide in oil. Such a paste can be made by grinding 185 
parts of zine oxide and 115 parts of OO litho oil several times 
through a roller mill. A strength test can then be quickly 
made by taking a small amount of the paste color made as 
outlined above for comparing the overtone and adding the 
proper amount of zinc oxide paste. 


308 Testing Colors for Tone and Strength 


For reduced colors a reduction of 20 to 1, i. e., 20 parts zine 
oxide paste to 1 part paste color, is usually sufficient but for 
C. P. colors a 100 to 1 reduction is necessary to get the proper 
idea of relative strengths. Very often two C. P. colors which 
apparently are about the same strength on a 20 to 1 reduction 
are very far apart on a 100 to 1 reduction. In making the re- 
duction test the best way is to counterbalance 100 milligrams 
of the two paste colors to be tested and then add to each, two 
grams of the paste zine oxide. Before removing from the 
counterbalanced watch glasses mix the color with the zinc 
oxide, using a small spatula thus minimizing the loss on trans- 
ferring, then remove from watch glass to a smooth piece of 
glass and mix with a spatula until the color no longer streaks, 
which indicates that it is thoroughly incorporated. Never make 
a strength test on a rough glass and do not rub with a muller, | 
as this develops strength that is not secured in factory prac- 
tice. In the event that a 100 to 1 reduction is desired, take 500 
milligrams of the first reduction, add 2 grams of zine oxide 
paste and proceed as before. 

If it is desired to express quantitatively the tinting strength 
of the color, consider the standard color as having a tinting 
strength of 100, and then vary the amount of the standard 
color until the tints are matched. | 


For example, let the amount of standard color for 100 strength test be 
0,029.) (= "47, Vary this amounts in units of 5 per cent, thus 0.019 or 
0.021. Let the amount taken to match a given strength = B, then 


A . 
— 100 
RB’ 


equals the tinting Strength of the sample to be tested. 
If the tone varies it may be difficult to make this measurement. 


The comparison for overtone should be made as soon as the 
colors have been applied to the strip of glass or tin, otherwise 
‘‘flooding’’ may result in one or both samples and there will © 
be no basis for comparison. 

Generally speaking, it is good practice to have separate rub- 
bing glasses for each of the four general classes of color— 
greens, yellows, blues and reds to avoid contamination of one 
color with another. If one glass is used for all colors, great 
care must be exercised to insure absolute cleanliness. It is 
surprising, for instance, how little chrome green is required 
to off-shade a primrose yellow. Benzol 90° is probably the 
best liquid for cleaning the rubbing glasses. 


CHAPTER XXI 
ACCELERATED TESTING CABINETS 


Accelerated tests on paint and varnish films, through the 
use of ultra-violet light, artificial rainstorms, and low and 
high temperatures, have received much attention during the 
past three years. The importance of securing in three weeks’ 


lh 


: 


| 
| 


i 


FicgurE 109—Cabinet recently designed and installed at writer’s laboratory. 


310 Accelerated Testing Cabinets 


time information that might require a year in ordinary roof 
exposure tests can readily be appreciated. Even though the 
results of such accelerated tests may not follow exactly those 
obtained by exterior exposure tests, they may guide the in- 
vestigator in determining the comparative life of certain coat- 
ings. Probably the first cabinet built to make tests on panels 
of fair size, that would afford means of a real study of the 
problem, was that designed by H. A. Nelson, who has kindly 
prepared a highly instructive resume of his important work, 
which appears on page 326. 


FIGURE 110 


Photographic view of Cabinet showing size as compared to observer. 


The writer and H. C. Parks recently designed and installed — 
an apparatus which subjects panels to four cycles: Heat, eold, 
rain spray and ultra-violet light. The entire apparatus is 
made of 16 gauge heavily galvanized iron. It consists of a — 
revolving drum five feet in diameter with a fourteen-inch face — 
upon which the test panels are fastened. The drum accommo- ~ 
dates 31 panels 6 inches by 12 inches and 1 inch thick. Such | 
panels are of greater size than used in most testing cabinets — 


Pay ee “ 


Accelerated Testing Cabinets Sid 


previously constructed. They afford sufficient surface for 
brushing or spraying a coating under test. The drum re- 
volves on bearings fastened to the sides of a tank 3 feet deep, 
arranged for holding ice water or refrigerating pipes. The 
drum is operated by a Ye H. P. 110 volt A. C. motor which, 
revolving at a speed of 1725 r. p. m., operates a pulley with 
a 64% to 1 reduction. The pulley is fastened to two worm 
gear units which give a further reduction of 8281 to 1, thus 
reducing the speed of the drum to 1 revolution per half hour 
(total reduction 51,750 to 1). 


The panels first pass in front of a rain spray furnished by a 
Schutte-Koerting spray nozzle No. 622-B, then pass below an 
ultra-violet ight furnished by a mercury quartz tube of the 
Cooper-Hewitt type No. BW-040. The panels then pass in 
front of a battery of twelve 100 watt electric bulbs which give 
the desired heating effect and some efficiency from the stand- 
point of light source. They then pass into ice water or over a 
series of refrigerating pipes to secure the desired cooling 
effect. The last two cycles may duplicate the strains developed 
on automobile finishes when a motor ear is driven from a 
heated garage (70° F.) into the open air on a cold morning 
(20° F. or lower). The rain spray and the ultra-violet light 
might be considered equivalent to alternate exposure to thun- 
der storms and strong sunlight in the summer months. The 
ozone produced by the Mereury Are Light may also greatly 
stimulate the breakdown of finishes. 


This apparatus has been in almost continuous use for a 
period of two years and has given much information regard- 
ing the durability of lacquer coatings. Exposure for 200 hours 
often gives the same type of chalking and surface decay that 
is observed upon roof tests conducted in the summer months 
for a period of from 60 to 90 days. The results, however, upon 
this type of accelerated testing cabinet do not approximate 
those obtained upon roof exposure tests with paints and var- 
nishes of the oil type, as will be shown on pages 312 and 313. 


One of the defects of this type cabinet is the fact that the 
panels are only submitted to the effects of ight during part 
of the revolution of the wheel. If the light had been placed 
in the middle of the wheel so that the panels would at all 
times have received exposure to the light, much more rapid 
results would doubtless have been obtained. A cabinet based 


Accelerated Testing Cabinets 


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Accelerated Testing Cabinets 


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Accelerated Testing Cabinets 


FIGURE 111 


Photo Micrograph X 50 of Pigmented Nitrate Dope 
on Accelerated Wheel 219 hours. 


FIGURE 112 


Photo Micrograph X 50 of Clear Lacquer (12-ounce 
solution of Cellulose Nitrate with Resin) on 
Roof 744 weeks. 


~ canal 


Accelerated Testing Cabinets 315 


FIGurRE 113 


Photo Micrograph X 50 of Pigmented Dope on 
Roof 7144 weeks. 


FIGuRE 114 


Photo Micrograph X 50 of Pigmented Dope in 
Ammonium Carbonate Cabinet 212 hours, 


316 Accelerated Testing Cabinets 


FIGURE 115 


Photo Micrograph X 50 of Pigmented Auto Lacquer 
on Roof 7% weeks. Surface roughness is due to 
chalking. No checking or other film defects. 


FIGURE 116 


Photo Micrograph X 50 of Outside White Paint on 

Accelerated Test Wheel 290 hours. Film scratched 

with Sapphire Needle Tester to show effect of ultra- 
violet light ‘on making film chalky. 


Accelerated Testing Cabinets 317 


upon such a design is now under construction. A description 
of it will probably appear in a scientific circular to be issued in 
November, 1927. 


Walker-Hickson Cabinet. A type of accelerated cabinet 
devised by P. H. Walker and E. F. Hickson of the Bureau of 
Standards has been in service at the Bureau for several 
months, with apparently satisfactory results. Much smaller 
panels are used in this apparatus than with the other types 
described in this chapter. There are shown herewith two 
views of the apparatus as described by Walker in his paper 
entitled ‘‘Some Methods of Testing Paint and Varnish Ma- 
terials,’’ presented before the International Congress of Test- 
ing Materials, at Amsterdam, Holland, September, 1927. 


FIGURE 117 


Ozone apparatus used by Walker and Hickson. 


318 Accelerated Testing Cabinets 


Figure 118 


Walker-Hickson tank with ultraviolet light equipment. 


Figure 118 shows carbon are equipment with lamp raised 
out of cylinder. When in use it is lowered so that the are 
is at the level of the center of the 7.5x15 em. test. panels 


Accelerated Testing Cabinets 319 


held in the slots on the inside of the cylinder, which is 76 em. 
in diameter, 38 cm. high, open at both ends and suspended 
with its lower edge 5 em. above the edges of a pan containing 
water. <A circular perforated tube serves to apply oceasion- 
ally a light shower of water to the panels while exposed to 
hght. 


Figure 117 shows cabinet for exposing panels to ozonized 
air. Air is forced by means of the small motor-driven fan, 
shown in the lower left corner, through a silica gel dehy- 
drator, then through a calcium chloride bottle, which serves 
to indicate that the silica gel is working efficiently, to the 
ozonizing aparatus and thence to the glass chamber on the 
right for holding the panels. Some water is placed on the 
bottom of this glass chamber to moisten the ozonized air. 
This equipment delivers about 660 liters per hour of air con- 
taining 0.56 liter of ozone, equivalent to about 0.08 per cent 
of ozone by volume. 


For the vigorous spraying with water the panels are trans- 
ferred to another cabinet, of which no picture is available or 
necessary. 


In the course of a week the panels are 112 hours in the light 
eabinet, 21 hours in the ozonized air cabinet and 32 hours in 
the rain cabinet. This leaves 3 hours for inspection. 


Hopkins-Murphy Cabinet.—An accelerated test apparatus 
used by F. W. Hopkins of the Murphy Varnish Co. is de- 
seribed below by Mr. Hopkins. 


Our apparatus consists of three tanks reproducing light, 
water and refrigeration. The light and water tanks are of 
wood, 31 inches high, 42 inches in diameter and are lined with 
galvanized iron. A 6-inch Cooper-Hewitt U V Arc Lamp is 
centered in the light tank as a source of ultra-violet radiation. 
The tank is also equipped with an automatic electric heat 
control, an atomizer and a circulating fan on the side which 
keeps the lamp cool. The air circulating system has a water 
jacket so that in summer the same temperature can be main- 
tained as in winter. The average temperature in the light 
tank is 140 to 150° Fahrenheit, and the relative humidity 75 
to 80 per cent. The water tank is equipped with an ordinary 
revolving lawn sprinkler which has three arms. 


The refrigeration unit consists of a brine tank and an inner 
compartment which is 24 inches in length, width and depth. 
These tanks are insulated with six inches of cork board and a 
¥z inch siding, also a double cover. A small Frididaire ice 
cream compressor 1s used to compress the sulphur dioxide 


320 Accelerated Testing Cabinets 


which circulates through a coil in the brine tank. The mini- 
mum temperature obtained is 20° below zero. 

The present cycle consists of 56.1 per cent light, 26.7 per 
cent water and 17.2 per cent refrigeration. 

Because of the high degree of distensibility of varnish, a 
change of panels from water to light, and water to refrigera- 
tion are more effective than the same changes when lacquer 
is being tested. In the case of lacquer, a light to refrigera- 
tion change effects a quicker breakdown. By the use of tem- 
peratures below 0 Fahrenheit, it is not necessary to use a fan 
to cool the panels in the refrigerator, as the sudden change 
from over 100° Fahrenheit to 0 Fahrenheit, a period of two 
hours, is sufficient time for the refrigeration exposure, the 
eycle having one change from light to refrigeration every day. 

A microscopical examination with a binocular microscope, 
using a magnification of 30X, is made of the panels once a 
week. In interpreting results, change of color, loss of lustre, 
chalking, peeling and cracking are considered. The change of 
color is determined whether due to the breaking down of the 
nitro cellulose, or a fading or darkening of the pigment used. 
The loss of lustre begins with the first signs of chalking, which 
takes approximately 150 hours’ exposure in the eyele. The 
amount of chalking is determined by rubbing the panel with 
a small piece of felt once a week, excess chalking being due 
to either an excess of pigment or lack of a binder. Under- 
eoats which do not properly adhere to the surface applied 
cause peeling. Cracks are caused by undry underecoats or 
an improper balance between the primer, surfacer and finish- 
ing coat. Crowfeet cracks are found only in the finishing 
coat. When a pigmented lacquer is tested over bare metal, 
a pinhead crack is formed, which in time causes the finish 
to peel from the metal, leaving small pits in the surface. A 
very interesting crack, hard to describe, is caused by an excess 
of plasticizer in proportion to the amount of nitro cellulose 
used. 

By increasing the oxygen content of the air in the light 
tank, the Research Division of the New Jersey Zine Company 
has found that they have increased the ratio of outside ex- 
_ posures in comparison to accelerated exposures from one to 
seven to one to fifteen. In comparison with roof exposures, 
we think that with the present cycle, a ratio of one to eight 
is established. With the data, which we have obtained from 
the New Jersey Zine Company, in mind, we have found that 
by the introduction of the ozone into the light tank by means 
of connecting the ozinator to the air circulating system, it is 
possible to produce the same cracking in approximately one- 


Accelerated Testing Cabinets 321 


third of the time that it takes without the use of ozone. The 
amount of ozone used is approximated at 0.25 grams per 
hour. 


Figure 119 


Weather-O-Meter for accelerated tests on protective coatings. 


322 Accelerated Testing Cabinets 


Atlas Weatherometer Cabinet.—An apparatus built by the 
Atlas Electric Devices Co. of Chicago has been in successful 
use in several paint laboratories. It is described below: 


The Weather-O-Meter is a new scientific instrument that 
shortens the weathering period of on-the-roof tests from 
months and years to days and weeks, and gives the plant 
equipped with a Weather-Ometer years of advantage over 
plants that are not equipped with an accelerated weathering 
machine. In this instrument the elements of sunlight, rain, 
and wind can be controlled to suit the requirements of the 
test that. is being run. This instrument predetermines the. 
weather resisting qualities of paint, varnish, lacquer, roofing 
material, rust-proof iron, alloy, and any material subject to 
outdoor weather conditions. 

In this instrument the samples to be tested rotate continu- 
ously, completing one cycle in twelve or twenty-four hours, 
depending upon the gearing arrangement, whether it is geared 
for two twelve-hour periods and one twenty four-hour period. 
The eighteen samples, which are usually 3 x 8 inches, are sub- 
jected to the elements of sun, rain, and wind in the following 
relationship : 

(1) Sunhght falls on the samples for sixteen consecutive 
hours. 

(2) Samples are now cooled to near 5 degrees below room 
temperature for a period of four hours. | 3 

(3) From the period of cooling the samples are subjected 
to four hours of rain, approximate temperature is 5° F.. below 
room temperature. 

(4) They are now turned back into the period of sunlight, 
which has its greatest destructive power here just as in the 
out-of-doors after a rain. All these periods may be varied 
according to the needs of the individual plants. 

(5) A temperature range can be adjusted through the ther- 
mostat so that the maximum and minimum ranges are variable. 
However, the usual range would be from 100° F. to 150° F., 
with control elements of 5 to 15°. However, without the 
blower, the temperature easily rises to 190°, which greatly 
accelerates the weathering test. 

Special features, such as thermostatically controlled shut- 
ter, which maintains a constant temperature, four thermo- 
meters, humidifier, blower, and other special apparatus, are 
included. 

The violet flaming carbon arc is the lamp used in this instru- 
ment, due to the fact that its spectrum so closely resembles 
that of sunlight and is the nearest possible reproduction of 


Accelerated Testing Cabinets ead 


sunlight in the out-of-doors. The big advantage of the carbon 
are lamp is that it is not easily breakable nor does it change 
in its constancy of ultraviolet rays as the lamp is used. 

The entire machine is made out of Monel non-rusting alloy, 
copper, brass, and machined steel. The meta] parts in contact 
with the water are all of rust-proof material. The instrument 
is finished in lacquer on those parts that do not already have 
a natural finish. : 

The instrument operates on a 220 volt, direct or alternating 
current circuit, the current consumed is 24 amperes. When 
operated on 110 volt A. C. circuit, a transformer is added to 
the cireuit to bring the voltage up to 220 volts. The instrn- 
ment does not operate on 110 volts direct current or an alter- 
nating current under 40 cycles or over 133. 


Croll-Jenkins Cabinet.—The accelerated exposure equip- 
ment used at the Milwaukee Laboratories of the Pittsburgh 
Plate Glass Co. (Paint Division) comprises a refrigeration 
room and a light and moisture tank. The refrigeration room 
proper is 9 ft. by 12 ft. by 8 ft. high. It is insulated by a two- 
inch layer of cork, and provided with a double window and a 
refrigerator door. Within this room is a tank 5 feet high 
and 6 feet in diameter, supplied by an individual air duct from 
the refrigeration equipment. The hight and water tank jis 
also 5 feet high by 6 feet in diameter. 

Both tanks are provided with hexagonal racks rotated by 
motors operating through speed reducers and bevel-gears and 
so arranged as to rotate once every ten seconds. 

The panels are exposed in panel holders. They hold three 
6° by 12” panels, bolted with brass bolts, one above another 
and spaced out from the holders by strips of 4% inch square 
beading at the top and bottom of each panel. This spacing 
provides drainage and air circulation behind the panels. The 
holders are hung vertically from the top bar of the hexago- 
nal rack by means of two small hooks on the back of the 
holder. The tanks are fitted with covers and the light tank 
is equipped with three Spray nozzles set one foot apart on a 
vertical pipe and adjusted to Spray evenly on the three rows 
of 6° by 12” panels from a distance of two feet. 


A 30° quartz mercury arc is suspended in the center of the 
tank through a 6” hole in the top. It is so hung that its center 
is on a level with the center of the middle panel. 


It may be assumed that over a relatively large number of 


324 Accelerated Testing Cabinets 

changes, from the water-light tank to the refrigerator tank 
and back, the law of chance will cause any one panel holder 
to oceupy each of the five possible positions an equal number 
of times. Consequently, the variation of intensity between 
the middle position for the panel holders and the outside posi- 
tions will be offset. 

The top and bottom panels, however, will always get less 
light than the corresponding center panel, about 90% for the 
top and bottom as compared to 100% for the center, and this 
can only be eliminated by changing the panels around. 

Most of the work with this equipment during the last nine 
months has been with lacquer base materials. Here it has 
been found very useful for comparative tests between rela- 
tively similar materials. Attempts to correlate the results 
of these tests with outside exposure panels, however, have 
been less fruitful. The reasons for this are fairly obvious. 


In the first place, the normal manner of failure of such 
finishes as automobile enamels and clear lacquers is by chalk- 
ing or disintegration by light. However, the variation in the 
amount of sunlight and its content of the active short wave 
lengths, or ultraviolet light, is very marked between summer 
and winter. As a result, lacquers will be much longer liyed 
during the winter than during the summer months on exterior 
exposure. 


In products which fail by cracking or checking, the type 
of failure can usually be approximated, but the time ratio 
of accelerated to normal exposure varies somewhat. 


McMullin Accelerated Cabinet.—E. W. MeMullin, Chemist 
of the Simmons Company, Kenosha, Wis., at a recent meet- 
ing of Committee D-1 of the American Society for Testing 
Materials, stated that he had devised an apparatus for test- 
ing finishes upon metal beds and similar material, by expos- 
ing the coated panels in a cabinet containing vapors of a 
dilute aqueous solution of ammonium carbonate. In a sub- 
sequent communication to the writer, he stated that the 
cabinet was 30” by 20” by 14”, made of a wooden frame with 
back, top and bottom of tongue-and-groove boards, and with 
glass doors on front and back. He used a graniteware dish 
having a capacity of about 2000 ce. kept supplied with a one- 
half of one per cent (0.5%) solution of ammonium carbonate. 
Wooden racks upon which to expose panels were placed above 


Accelerated Testing Cabinets 325 
 _____._.._.____.._._— 
the pan. Air vents were supplied at the bottom and top of 
the cabinet, and a gas burner for heating the solution. Using 
a wet and dry bulb thermometer, and by regulating the flame, 
the temperature was kept about 95° F. and the humidity 
about 90%. He stated that while he has not sufficient data 


=== 
———— = 


9 GOA 


Figure 120 


Accelerated Test Cabinet for Metal Finishes. 


to compare the length of time a finish stands up in this cabinet 
to its outdoor or even indoor exposure, he can obtain some 
idea of the practical life of a finish and get a very close com- 


326 Accelerated Testing Cabinets 


parison of the value of any two finishes when exposed simul- 
taneously in the cabinet. 


Based on the above, the present writer has designed a some- 
what similar cabinet as shown in the attached Figs 12a 
It is made of heavily coated galvanized iron of 18 gauge, two 
and a half feet square, three feet high, and provided with a 
metal cover. An electrical heating device is used instead of 
a gas flame. A somewhat different arrangement of the pan- 
els is made, suspending them rather than placing them upon 
racks. The cabinet has a cover supplied with air vents. Tests 
made with this cabinet apparently do not check with the results 
obtained with cabinets in which there is exposure of the panels 
to cycles of ultraviolet light and water spray or with exterior 
exposure tests. Nevertheless, the results may be compara- 
tive and thus afford some information when studying the 
possibilities of a number of different finishes for one specific 
purpose. 


Palmerton Cabinet.—More work has probably been done 
by Nelson and Breyer of the New J ersey Zine Co. laboratories 


Atomizing 
7 Sproy nozzles. 


FIGURE 121 


Type of apparatus that has been successfully used in accelerated 
weathering experiments. (Nelson. ) 


Accelerated Testing Cabinets aya 


than by any other investigators in this country on the subject 
of accelerated tests involving ultraviolet light. The work of 
these investigators covers a period of several years. The 
importance of their work is so great that there has been pre- 
sented below an article on the subject, describing their appa- 
ratus and the developments to date. This article, which 
has been prepared by H. A. Nelson and F. C. Schmutz, is 
presented in full, together with a number of illustrations. 


March Apr Ma JUure July A 


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FIGURE 122 


Comparison of gloss depreciation curves on typical single pig- 
ment paints under outdoor and accelerated weathering condi- 
tions. (Nelson.) 


328 Accelerated Testing Cabinets 


Valuable beginnings of experimental work with accelerated 
tests were made by Gardner’ and by Muckenfuss?. The lat- 
ter developed an exposure scheme which was designed to take 
advantage of the changes in permeability of paint and var- 
nish films, applied on fine mesh screen or hardened paper, to 
moisture as a measure of deterioration under artificial expos- 
ure conditions. The exposure involved lght (mereury are 
and tungsten), moisture (revolving spray) and cool weather 
(outdoor night exposures). 

Other, more recent, investigations*® were directed toward a 
possible simplification of the application of the idea of accel- 
erated weathering. The ideal would, of course, be artificial 
accelerated reproduction on painted wood and metal surfaces 
of the normal failures that are observed under outdoor expo- 
sure conditions. The first laboratory evidence that this might 
be possible was the fact that an ordinary 100% Basie Car- 
bonate White Lead—linseed oil paint film could be made to 
chalk heavily by exposure for about 13 hours under an ordi- 
nary 220-volt mereury are lamp. The particular importance 
of the radiations from the ultraviolet portion of the spectrum 
(below A = 3800 A. U.) was then demonstrated by the fact that 
only some loss of gloss could be obtained by exposing similar 


Section 8 
Latches 
4 


pa 


Revolving Spray 


Fig. 1 
Section A 


A-Exposure Tank J- Humidifier 
B-Mercury Arc K- Steam Jacket 
C- Oxygen Inlets L-Water Drain 
O- Rubber Seal M-Air Pump max. cap. 20cu.ft per min. 
E- Psychrometer (Wet & Dry Bulb)- N-Silica gel Dehydrator 
F~ Air Circulating Fan O-Compressed Air 
G- Paint Panels (Cap. 50- 9"«12’) P-Heater 
H- Peep Hole Q-Air Cooler 
I- Gas Inlet R-Water Inlet 
FIGURE 123 


Plan of accelerated testing equipment at New Jersey Zine Compuny’s Research 
Laboratory at Palmerton, Pa. 


Accelerated Testing Cabinets 329 


films for about 300 hours at a short distance from an ordinary 
glass blue-printing lamp (mercury arc). 

For further experiments, a special vertical quartz burner, 
30° long, was developed so that panels in large numbers and 
of appreciable surface area (6°x12") might be used. Only 
light and moisture were extensively used in the first experi- 
ments and the following results were obtained with paints 
and varnishes on wood and metal panels: 

(1) Loss of gloss and subsequent chalking were easily re- 
produced by exposure to ultra-violet radiations in and below 
the region 4 = 3600 A. U. 

(2) Loss of gloss and chalking were hastened by periodic 
saturation of the paint film, or by maintaining a saturated 
atmosphere in the apparatus during the period of ultraviolet 
exposure. | 

(5) Paints made with pigments which chalk readily upon 
normal outdoor exposure were the ones which chalked readily 
under the ultraviolet light. Those pigments which normally 
retard loss of gloss and chalking under outdoor exposure 
conditions were found to act similarly under the accelerated 
conditions. 

(4) Comparisons made with results from outdoor exposures 
showed a ratio of approximately 1 to 30 for loss of gloss and 
initial chalking. For this the accelerated exposure scheme 
was 24 hours light-cool-24 hours water spray. This approxi- 
mate ratio was then found to exist for’a number of paint 
combinations representing both chalking and non-chalking 
pigments. (It should be noted, however, that low tempera- 
ture exposures were not generally included in these experi- 
ments, and that the conditions of the exposure were what are 
ie to be very severe for producing a chalking fail- 
ure. 

(5) Chalking, onee started by exposure to light, was ac- 
eelerated by exposure to low (freezing) temperatures, espe- 
cially when the film had been previously saturated with mois- 
ture. 

(6) Cracking was then reproduced to a limited extent on 
certain paints and varnishes, but only with marked success 
when some variations of temperature were introduced (out- 
door exposures in winter were used). 

The above results went far toward proving the practica- 
bility of the method, and the experiments were continued after 
the installation of a refrigerating equipment which made low 
temperatures available down to about —16° C. 


Effect of Variations in Exposure Cycle.—The possible ef- 


330 Accelerated Testing Cabinets 
I 


fective variables which could then be introduced with the 
equipment at hand were: 

(1) Light and heat (50° C. to 60° C.) at comparatively low 
humidities. (Air taken in at outdoor temperatures.) 

(2) Light and heat with saturated atmospheres. 

(3) Water spray (washing action of rains). 

(4) Low temperatures (down to —16° C.). 


FIGURE 124 


Accelerated Weathering Equipment—Unit for exposure to light and water 
under controlled conditions (see Figure 123). Capacity 50 panels, 6” x 12”. 


Early in the work it was evident that the ratios between 
outdoor and accelerated weathering would vary with the 
nature of the exposure cycle used. That great variations in 
the rates of outdoor deterioration are introduced by climatic 
differences is also common knowledge. Obviously, then, the 
next important step was to begin a study of the relative deteri- 
orating effectiveness of each weathering factor (alone and in 
combinations) as it might be used in an accelerated weath- 
ering cycle. 

A comprehensive series of tests with this object in view was 
made on a group of representative varnishes, of which the 
detailed results can be found in the literature.t It is im- 
portant to note that very great variations are observed in the 
degree and type of deterioration, depending what factors are 


Re 4 ca foe 


Accelerated Testing Cabinets aieM! 
NN eS SSS Sess} 
included in the exposure cycle and the frequency of change 
from one kind of exposure to another. Briefly, the following 
conclusions were arrived at as to the apparent relative deteri- 
orating effectiveness of the exposure factors. 

(1) Most effective (especially in deadening or reducing 
the distensibility of the film) was a water exposure followed 
by light. | 

(2) Second and almost as effective was the water exposure 
followed by refrigeration. This apparently not only helped 
take the elastic life out of the film, but also acted as a factor 


in revealing the deterioration brought about under hght and 
water, ete. 


OUTDOOR RESULTS 
Paint No. 1 Paint No. 2 Paint No. 3 


Paint No. 1 Paint No, 2 Paint No. 3 
ACCELERATED RESULTS. 
FIGURE 125 


Photomicrographs of typical paints, showing failures produced by accelerated 
and outdoors exposures. 


(3) Next in effectiveness was light (warm and dry) fol- 
lowed by refrigeration. This combination apparently served 
largely as a factor which brought out, or revealed weaknesses 
in the film which might be inherent with the original material 
or introduced by other exposures. 

(4) Considerably lower in effectiveness was the action of 
light alone. (This refers to the ‘‘deadening”’ action of light 


332 Accelerated Testing Cabinets 


after the excess absorbed water has passed off and the film 
‘is fairly dry. The lower the moisture in the film the slower 
is the action of light.) 

(5) Next was water alone which, in itself, appeared to have 
a deteriorating effect. 

(6) Continued refrigeration, after the film had attained 
equilibrium at the low temperature, had no appreciable de- 
teriorating effect. 

Exposure cycles involving moisture and light were most 
effective when changes were made frequently. Thus the 
film was practically always in a saturated state and the light 
did most damage. Light-refrigeration cycles brought about 
eracking most quickly with frequent changes, but the final 
deterioration was greatest under longer periods of exposures 
when the light deterioration became proportionately greater. 
Water-refrigeration was most effective with moderately fre- 
quent changes. 


More Recent Development of Apparatus—Oaygen and 
Ozone Atmospheres.—Up to this stage of the investigations, 
difficulty had been encountered in reproducing common check- 
ing types of failures such as commonly appear on ordinary 
paint surfaces. Consideration of the possible causes of this 
type of failure lead to the conclusion that it is induced to a 
large extent through excessive hardening or contraction of 
the paint film at the surface. To test this, an apparatus was 
so designed that the oxygen content of the atmosphere could 
be increased at will. A concentration of 30% by volume of 
oxygen was used. The results were gratifying, checking types 
of failures being reproduced. Another result was that the 
general deterioration rate for paint films was practically 
doubled so that the whole testing process was speeded up. 


It was then suggested that ozone be tried instead of oxygen. 
However, its activity proved so great and the mechanical dif- 
ficulties in providing exact control of the quantities of ozone 
introduced were such that the results in these experiments 
were not encouraging. One effect noted, even when very 
small proportions of ozone were used, was the extreme ten- 
dency of lead bearing paints to darken due to the formation 
of a reddish brown surface film of lead oxides. 


Conditioning of the Atmosphere in the Light Exposure 
Chamber.—The desirabilitv of having periodic exposures 
under dry atmospheric conditions is evident when we consider 
the effect of absorbed moisture on the physical pronerties of 
oleo-resinous films, in particular, and on nitrocellulose films 
where appreciable amounts of more or less hygroscopic gums, 


Accelerated Testing Cabinets S33 


etc., have been incorporated. For testing work of this kind, 
there is no obvious reason why we should be particularly in- 
terested in reproducing any conditions except the two ex- 
tremes—saturated and dry. A great forward step in main- 
taining these conditions in an easy and practical way was 
accomplished by substituting a simple silica gel dehydrator 
(‘““N”’ Figure 123) for air conditioning by refrigeration. This 
necessitated apparatus so designed’ that the air could be re- 
circulated through the dehydrator. In order to relieve the 
silica gel dehydrator of excessive load, a condensing coil 
(“‘Q”’ Figure 123) is provided in the cireuit, which removes 
part of the moisture. In this manner the conditions in the 
exposure chamber can be changed from saturated to approxi- 


Accelerated ; Outdoor 
FIGURE 126 


Comparative results on two white outside house paints, one of which tends 
to crack and the other to chalk away uniformly in service. 


: ‘ 
ay ens . 


334 Accelerated Testing Cabinets 


Accelerated 


(with auxiliary exposure to SO,, CO, and air mixture) 


en ee 


ee aes 


Outdoor (45° angle, facing south) 


FIGURE 127 


Comparing results of industrial accelerated and outdoor exposures r 
of paint on steel sash bars. 4 
& 


mately 5% relative humidity in times ranging from 10 to 30 
minutes, depending on the size of the unit. 

The exposure unit shown in Figures 123 and 124 represents 
equipment designed to enable the operator to reproduce any 
of the following conditions at will: 

(1) Light (Mercury or Carbon Are) 

a. At controlled temperatures. 
b. With 100% relative humidity. 


Accelerated Testing Cabinets 335 


e. With less than 5% relative humidity. 
d. In atmospheres charged with active gases, as, for 
example, oxygen. 


(2) Water Spray (by removing the Light and Substituting 
the Revolving Spray). 

This unit, constructed of galvanized iron and, using ordi- 
nary pipe fittings throughout, complete with pump, dehy- 
drators, spray equipment, 20” quartz mercury are, control 
equipment, etc., cost between $550 and $600. Obviously, the 
use of Monel metal and brass for many parts would be good 
economy, although it might increase the cost by $50 to $100. 


Aualiary Exposures to Corrosive Gases (SO2 and COz)— 
Such an auxiliary test® has been inserted with considerable 
success in the regular weathering cycle for testing metal pre- 
servative paints, in particular. This part of the test is con- 
ducted in a,dark chamber with a high humidity and a tempera- 
ture of about 100° F. (These gases seem to have very little 
effect on a paint film while it is being exposed to light.) The 
gases have been used in proportions such as 1000 parts of air’ 
to 12 parts carbon dioxide and 1 part sulfur dioxide. Higher 
gas concentrations had better be avoided in order to keep the 
formation of water soluble reaction products from becoming 
too much of a factor in the deterioration process. 


Comparison with Outdoor ,Exposure Results.—As pre- 
viously stated, in the early experiments a certain approximate 
relation was established between outdoor and accelerated 
weathering results, especially in so far as chalking types of 
failures were concerned, when moisture and hght were the 
major factors involved. It was also subsequently pointed 
out that this ratio did not hold when the exposure cycle was - 
modified to any appreciable extent, as, for example, by adding 
low temperature exposures. 

Figure 122 illustrates how deterioration of outdoor expos- 
ures, as measured by loss of gloss and chalking, compares 
with an arbitrarily selected accelerated exposure cycle in 
which light, moisture and refrigeration have the same aver- 
age ratio as observed for sunshine, rain and low tempera- 
tures at Palmerton, Pa., for a period of one year. The curves 
are plotted on a 1.7 ratio (outdoor exposure March to August, 
inclusive — 1924). But experiments also showed that this 
1.7 ratio may not hold if the outdoor exposure is begun at 
another season, nor have we any reason to expect that it 
would. Hssentially, then, all that these curves tell is that 
the reactions of the films to the weathering agents as they 


336 Accelerated Testing Cabinets 


were used in this experiment are very similar even with 
paints made with pigments that differ so radically in their 
known properties, but this in itself is very significant. 

Until oxygen was added to the atmosphere in the light 
exposure chamber and effective means were provided for in- 
troducing humidity changes as mentioned above, checking — 
and cracking types of failures were not reproduced in a very 
representative manner. This was the case with paints, es- 
pecially. Figure 125 shows photomicrographs of three repre- 
sentative exterior paints on steel which illustrate the results 
obtained when the full combination of weathering agents was 
used, as compared with exterior exposures of the same 
paints. The exposure ratio when the photographs were taken 
was 1:19. Other tests have indicated a ratio of from 1:14 
to 1:16 for the beginning of chalking or checking. Con- 
sidering the large number of variables involved, these results 
have shown a fair degree of concordance. , 

The additional use of auxiliary exposures to dilute SOs, 
CO. and air mixtures (see above) in testing the corrosion 
resistance of industrial paints on iron and steel does not ma- 
terially upset this ratio, as demonstrated by the photographs 
shown in Figure 127 of a series painted steel sash bars. The 
ratio of exposure of the samples as shown was approximately 
1:12. It is important to note the excellent agreement of the 
relative results attained by the two tests on individual sam- 
ples. | 

The problem of establishing an exact ratio is complicated 
by the variations in atmospheric conditions. It would be 
surprising, indeed, if the ratios found for Eastern Pennsyl- 
vania, for example, would agree with the same exposure cycle 
when compared with exposures in the South or Middle West; 
that is, the accelerated cycle will have to be modified to suit 
the exposure conditions that are to be simulated. Possibly 
climates can be classified according to characteristic types 
and a series of standard cycles designed to meet the require 
ments of any particular class of climate. 

Light Sources.—Practically all of the work so far reported 
on accelerated weathering of paint and varnish products has 
been done with the mercury are. Convenience in handling 
and the fact that the long tubes permit uniform exposure of 
large test surface areas have undoubtedly encouraged their 
use. But essentially, there is no reason why other sources 
of ultraviolet energy should not be used if they can be made 
mechanically adaptable to the other requirements of the test- 
ing scheme. Treated carbon electrodes” that closely simu- 
late sunlight are now commercially available. (Such as the 


Accelerated Testing Cabinets 337 


National Carbon Company’s Therapeutic ‘‘A’’ electrodes.) 
However, such treated carbon ares are more difficult to handle 
within an enclosing globe because of the rapidity with which 
the products of combustion from the electrodes cloud the sur- 
face of the globe. Experiments are now under way with 
apparatus designed to overcome this difficulty, but no results 
can be reported. 

The mercury are does have a serious weakness in the fact 
that the ultraviolet transmission of the quartz tube drops as 
the burner is used. Flynn’ reports an interesting way to 
compensate for this. He found it desirable to mellow the 
burners for about 500 hours. This was accomplished with a 
220-volt burner by starting it at 160 volts drop in the are 
proper and increasing the voltage drop at the rate of 2 volts 
for every 100 hours of operation for the first 500 hours. After 
this, he claims, no change is necessary during the remaining 
several thousand hours of the life of the burner for dye test- 
ing. 

Whether or not the radiations in the ultraviolet have a 
selective action on linseed oil and other organic binders, or 
if the deteriorating effect merely increases directly as the 
wave lengths of the ultraviolet radiations are decreased, is a 
question that has caused much concern among those interested 
in this problem. The experience of the dye industry, as 
shown by Harrison* and Flynn® is that for certain dyes, which 
are faded by reducing reactions, the radiations below about 
4 = 2900 A. U. must be filtered out to obtain results compara- 
ble with sunlight exposures. This is especially true on cotton 
which, Flynn concludes, becomes very actively reducing under 
the action of radiations much below 4 = 2900 A. U. Aceord- 
ingly, for such dyes, the are was tempered by interposing thin 
sheets of crown glass. It is possible that such side-reactions 
might also take place in paint and varnish films, but the indi- 
cations are that under the experimental conditions these are 
not an important factor, if they take place at all. For ex- 
ample, preliminary experiments (28 inches from a 220-volt 
D. C. 30” tube, operated at 9 amperes) on paints with a series 
of special glass filters, which cut out the ultraviolet step by 
step, show that all of the gloss reduction curves under the dif- 
ferent filters are quite similar in form, the main difference 
being in the rate at which the gloss falls off and surface chalk- 
ing takes place. That is, filtering out the shorter wave lengths 
of ultraviolet light merely lowers the rate at which the deteri- 
orating reactions progress. 

Recent spectrograms, reported by Stutz,’° of tungsten spec- 
tra (which are practically continuous) taken through films 


338 Accelerated Testing Cabinets 


of linseed oil throw further light on this subject. These 
spectra show no absorption bands within the range covered 
by the mercury are, which would indicate that no selective 
action on linseed oil, at least, is to be expected. However, in 
this same work, it is shown that the short wave lengths are 
largely absorbed at the surface where their action would be 
concentrated. This would account for the excessive chalk- 
ing observed when samples are exposed under an are that has 
a very large percentage of energy in the ultraviolet, as the 
6° clear quartz high pressure mercury are. 


It should be noted that the results shown in Figure 122 are 
from panels exposed without interposing any light filter. 
Properly speaking, however, this light source (30° are) is 
tempered when we consider the distance from the are (28 
inches) and the fact that the quartz used in these burners is 
not of the highly transparent grade. (The so-called Thermal 
Syndicate Stock quartz is used.) The results in this labora’ 
tory in favor of using burners of this type, which can now be 
obtained in 30", 20” and 10” lengths, have been quite convincing 
and they are recommended for use in accelerated weathering 
tests where the mercury are is to be used. 


Hxposure Cycles.—The development of suitable exposure 


eycles is in itself a subject that cannot be adequately dis- 
cussed here and the reader is referred to the literature on the 
subject.’,° A great deal of work remains to be done on this 
subject. However, a typical cycle, that has met with a rea- 
sonable degree of success when used i in testing paints intended 
to meet industr ial exposure conditions, as encountered about 


the industrial plants at Palmerton, Pa, i is as follows: 


TENTATIVE CYCLE FOR INDUSTRIAL EXPOSURE CONDITIONS.* 


Refrigeration......... 2 hrs. 
Water oa sini ieee 2 hrs. 
MONnGAY 7 oh. ee eas Industrial Gage. sca 1% hr. 
| Bates 5! dep: acnaar onan Y% hr. 

Light. .4invs a cate Cee ee 18 hrs. (16 hrs. dry, 2 hrs. wet) 
Water core i aves eee 2 hrs. 
Industrial Gas........ 1% hr. 
Tudsdayins «+ vviais™ | WADEES Avie le oa tee % hr. 
Refrigeration........<. 2 hrs. 

| Tights AP ERA TAL 18 hrs. (16 hrs. wet, 2 hrs. dry) 
( Refrigeration......... 2 hrs, 

Wednesday...... ae Was) ser Pee Ges 4S oes DS DIS. Cre 

LAY Otel oy cocaie keer 16 hrs. 


* For non-industrial exposure conditions, omit the industrial gas exposures 
and substitute water exposure during these periods. 


vp enn ial 


Accelerated Testing Cabinets 339 


. Retrigeration.....:..- 2 hrs. 
EO Sia be paced Aad ace ee 2 hrs. 
MRMTSOAY:...>>+- POOUStrisl Gas...-5-.. 1% hr. 
ti PD UL y epic shi = Dpiinceie'e ce 1%, hr. 
ALE Sa og ae pare osha, 9 oar 20 hrs. (dry) 
( Refrigeration......... 2 hrs 
Merve sc gie'a vetwie b 8 6.08 2 hrs. 
SE oy industrial Gas.......«. Y% hr. 
IE ERNE aha ia Pianos tae oe tw ¢ IN sh 
oo ne! a aa cai erat te ae 18 hrs. (wet) 
PRetrieceration.: 2.0. 2 hrs. 
| We Maes vee ov o.5°s.0 m9 2 hrs. 
CUE) Industrial Gas........ Y% hr. 
ea Y% hr. 
OC i Eo 15 hrs. (wet) 
Sunday to 
MONGAY. 24+... ; RNA a: nin’ 9's 635 6 27 hrs. (24 hrs. wet, 3 hrs. dry) 


Finally, a word of warning might not be out of order to 
those who begin using accelerated weathering tests, for the 
problem is a complicated one, at best, and many important 
questions still remain to be answered. For example, the ad- 
herence of lacquers is so affected by temperature changes 
that this exposure factor must be handled more cautiously 
when such materials are under test in order to avoid accen- 
tuating adherence failures. Additional experimental work 
is needed to learn where the line should be drawn. It can be 
said with entire confidence, however, that once some experi- 
ence has been gained in making observations and handling 
the equipment, the results will be invaluable to anyone inter- 
ested in a rapid estimation of the weathering qualities of pro- 
tective coatings. 


REFERENCES. 


1. H. A. Gardner—Paint Technology and Tests—1911, also Physical 
Testing of Paint and Varnish, Circular No. 122, Ed. Bureau, Paint Manufac- 
turers’ Association of U. S. 

2. A. M. Muckerfuss—Preliminary Report upon a Practical Accelerated 
Test for Paints and Varnishes—Journal Industrial and Engineering Chemistry, 
Vol. 5, No. 7, July, 1913. 

3. HH. A. Nelson—Accelerated Weathering of Paints on Wood and Metal 
Surfaces—Proe. A.S.T.M., Vol. 22, Part II, 1922. 


4. Nelson and Schmutz—Further Study of Accelerated Weathering—Proc. 
A.S.T.M., Vol. 24, 1924. 

» HH. A. Nelson, F. C. Schmutz and D. L. Gamble—Accelerated Weather- 
ing; Further Development of Apparatus and Exposure Cycles—Proc. A.S.T.M., 
Vol. 26, Part II, 1926. 

} 6. i. A. Nelson and F. C. Schmutz—Accelerated Weathering—A Con- 
sideration of Some Fundamentals Governing its Application—J.I.B.C., Vol. 18, 
No. 12, p. 1222, Dec. 1926. 


340 Accelerated Testing Cabinets 


6a. W. W. Coblentz, M. J. Doreas and C. W. Hughes—“Radiometric 
Measurements on the Carbon Are. ete.”—U. S. Bureau of Standards Scientific 
Paper No. 539, Nov. 19, 1926. 

7. Oscar R. Flynn—How the Mercury Are was Made to Imitate Sunlight— 
American Dyestuffs Reporter, Vol. XII, pp. 837-43, Nov. 19, 1923. 

8. William Harrison—Journal of the Society of Dyers and Colorists, 
July, 1912. 

9. Oscar R. Flynn—Am. Dyestuffs Reporter, Vol. XII, pp. 887-43, Nov. 
19, 1923. 

10. G. F. A. Stutz—The Absorption of Ultraviolet Light by Paint Vehicles 
—Paper presented before Division of Paint and Varnish Chemistry, A.C.S. at 
Richmond, Va., April, 1927. 

11. C. A. Knauss and J. G. Smull—Reaction of Bromine and Linseed Oil 
in the presence of Ultraviolet Light. Paper presented before A.C.S. at Rich- 
mond, Va. April 1927. 


all al tet 5 a 


CHAPTER XXII 


EXPOSURE TESTS 


The usual purpose of exposure tests is to secure information 
on the durability of paint products in comparison with those on 


ROOFING 


FIGURE 128 


New Type Test in Washington. 


which durability tests have already been made. Thus, for 
instance, if a new formula is suggested to replace an existing 
one, which for many years has been standard, it is to be ex- 
pected that exposure tests will give some indication of the 
relative differences which might exist between the two types. 
The purpose for which a test is proposed should, therefore, 
be given consideration in designing the test. In this connec- 


342 Exposure Tests 

a 
tion. it is well to point out that tests made upon small panels 
seldom give the length of life which is observed with the same 
paint in actual house painting practice. This may be due to 
the fact that paint is applied to small panels with a small brush 
dnd a fairly thin film results, whereas paint applied to the 
side of a house is usually applied with a large brush and a 
thicker film is obtained which will naturally have a greater 
durability than a thin one. This condition also accounts for 
the greater spreading rates that are recorded in paint testing 
on a small scale as compared to actual spreading rates ob- 
tained when paint is used on a large job in a practical manner. 
There are many other variables which enter into the testing 
of paints on a small scale, and it is doubtful whether such 
tests can be made the basis of positive statements as to the 
durability of paints over long time exposures on large struc- 
tures. 


Wood Panels—In exposing exterior paints upon wooden 
surfaces, the type of wood selected for the panels should be 
given careful consideration. It has already been shown by 
extensive tests now being conducted in sixteen different parts 
of the United States that the character of wood has a very 
pronounced influence upon the durability of the coating. These 
tests have also indicated that different results may be obtained 
with the same paint upon panels of flat and of edge grain. 
Whereas a paint may give satisfactory service on the edge 
erain, it may in some instances show longitudinal cracking 
upon the flat grain. Tests have also indicated that while 
paint may give satisfactory service upon a soft, uniform 
species of wood like white pine or poplar, inferior results may 
be obtained upon some species of yellow pine; and that red 
cedar, if not saturated with moisture, may constitute one of 
the best painting woods. For that reason red cedar panels 
might to advantage be adopted for exposure tests, since this 
wood.is now in wide use throughout the country as siding for 
dwellings. If the object of testing is to show the relative 
value of various paints, elimination: of faulty lumber is the 
most important consideration. Red cedar, cypress, white pine 
and poplar are woods which are obtainable with fairly uni- 
form grain and all of these different species have been recom- 
mended by various paint experts. In the writer’s opinion, 


el 


Exposure Tests 343 


FIGURE 129 


Newer Type Paint Exposures on Roof of Washington Laboratory. 


344 Exposure Tests 


however, red cedar is preferable to the other species men- 
tioned, provided it is used in a fairly dry condition. 


It would appear that one of the chief causes for failure of 
many types of paint exposed under severe conditions is the 
contraction and expansion of the wood panels, caused by 
moisture absorption and elimination through the unprotected 
backs of the panels. Under such conditions, the changes in 
volume of the wood are so great that many paint coatings are 
not sufficiently elastic after exposure for a year to withstand 
the stresses developed. Consequently, the films erack or scale. 
These defects are generally observed when panels are put out 
without any priming coat on the back or when a single priming 
coat is used without any additional protection. Wind driven 
rain striking the back of a panel gradually works through 
causing volume changes which are soon evidenced on the 
surface films. This condition is quite clearly depicted in 
some of the illustrations presented herewith. 


To guard against the conditions referred to above and for — 
large size tests that are to be continued in one locality for 
several vears without the necessity of bringing the panels 
back to the laboratory for examination, the type of construc- 
tion depicted in Figs. 128 and 129 is suggested. This type of 
test fence simulates very closely that used in actual house 
construction, the sheathing applied to the uprights being insu- 
lated with a sheet of asphalt-saturated felt roofing paper over 
which the weather-boarding is attached. One exception is 
that the panels applied as shown in the illustration are all 
primed on the backs as well as the faces. The type of primer 
used is discussed later on. The wood used in the test fence 
referred to is high quality red cedar siding 10 inches wide and 
6 feet long. 


After carefully selected siding is dried in the laboratory 
under normal conditions for a period of two weeks to eliminate 
any excess moisture, the sections are primed all over (front, 
back and edges), allowed to dry overnight, and then placed 
out of doors for a week to secure firm, hard dried films. They 
are then nailed in place upon the test frame, the nail holes 
puttied and two coats of the white or tinted paint under test 
is applied, allowing a period of at least five days for drying 
between coats. 


345 


Exposure Tests 


pesn 


spouvd 


‘UoTpnpoider dTYdBiso.oTMoJoyd PUB UOTJVUTMBxXd IoJ L10}RIOGB]T 0} PoeuINjal puw peAomer ATYonD aq ABU 
‘BPHOLA ‘a[[TASouTey UL SeAOIH [IO Suny, Iv YISue, Ul Joey perpuny [VsaAes VvoUT So} JuTed Jo UOTeEg 


OSL aNnDI 


546 Exposure Tests 


It is possible that two coats of paint applied over the spe- 
cial primer used will be much more durable than three coats 
applied direct to the surface of unprimed wood. Moreover, 
the use of the special primer which is of pronounced color, 
affords a surface which only white paints of good opacity 
will hide perfectly in two coat work. Thus, an idea may be 
gained of the comparative hiding power of the various test 
paints being applied. If paints are tested, which chalk with 
extreme rapidity, or which wash readily, the dark pink color 
of the primer will soon be evidenced and aid the inspector in 
judging the life of the test paint. 


Another type of panel (only three feet long) which the 
writer has recently adopted for panels which are to be exposed 
in different parts of the country and sent back to the labora- 
tory occasionally for microscopic examination, is shown in 
Figs. 130 and 131. This consists of the same type of red cedar 
siding referred to above treated in the same way, and primed 
in the same fashion. The difference, however, consists in 
applying the paints in the laboratory to avoid dust retention 
or rain spotting during the initial drying period. Hach coat 
is dried in the laboratory overnight, and the panels are then 
exposed out of doors between coats for a period of at least 
five days. After finishing the panels, they are exposed upon 
a type of frame construction shown in Fig. 130. They are 
fastened to the longitudinal board with two galvanized iron 
screws which are later touched up with the special priming 
paint to prevent corrosion. These screws may be readily re- 
moved at any time and the panels shipped back to the labora- 
tory for examination and then returned to the place of expos- 
ure for further test. 


There exists a wide difference of opinion among experts 
as to whether test paints should be applied out of doors or 
within the laboratory. If applied inside and no exterior ex- 
posure is given between coats, the unhardened undercoats 
will often cause. checking of the top coats. Moreover, if such 
panels are exposed out of doors during a winter month when ~ 
frost and moisture prevail, or in an industrial community 
where acid gases are prevalent, the semi-soft films will rap- 
idly take up moisture and washing troubles will ensue. At 
the same time, it should be mentioned that paints applied to 
the outside of dwellings in similar months and under similar 


Exposure Tests 347 


conditions may also show washing, due to the fact that the 
films do not receive the hardening which takes place when 
there is strong sunlight and good drying conditions. It is, 
therefore, necessary that the time and place of exposure of 
test panels be considered most carefully. Houses are painted 
under many kinds of weather conditions in widely scattered 


FHiaurE 131 
Detail of New Type Test in Florida. 


sections of the country. It would seem hopeless to attempt 
to standardize upon exact methods of exposure, as they could 
not always correspond to the conditions which prevail 
throughout: the country. 


Spreading Rate.—In conducting a paint test, it is usual to 
determine the weight per gallon of the product under test. A 
sample of the thoroughly mixed paint is first placed in a wide 
pint cup and this is weighed together with the brush. After 


348 Exposure Tests 


application of the paint, the cup with the remaining paint and 
the brush are reweighed to determine the amount of paint 
actually applied to the panel. From the weight of paint ap- 
plied, the spreading rate can be calculated, based on the num- 


FIGURE 132 
Paint Failure on Panel Not Properly Protected at the Back. 


ber of square feet of panel surface covered. In some special 
tests, paints are applied to a definite spreading rate by pour- 
ing upon the panel a definite volume of paint and brushing it 
out over the desired area, regardless of thickness or thinness 
of film. The customary procedure, however, is to apply the 
amount of paint that is required by the surface and then esti- 
mate the spreading rate obtained. : 


Angle of Exposure.—It would appear from tests conducted 
by the writer that if a paint gives good service in an upright 


SA Stew 


:? 
~ 


ae as gael ie 
BR Mee Se 


Exposure Tests 349 


position upon weather boarding for a period of four years, 
the exposure required to present the same condition when 
exposed at an angle of 45° to the vertical, facing south, would 
be two years. Thus the period of exposure required to deter- 
mine the life of a paint coating is cut in half by using this type 
of exposure. If there is added a cycle of water spray between 
12 and 1 o’clock every day during the summer months, say, 
for instance, from April 1 to October 1, the time required 
to give the same results may possibly be cut down with some 
classes of paint to a period of from 15 to 18 months. This 
would then constitute a semi-accelerated test of a practical 
type. 


— Colors.—If a white paint of a new formula is being tested, 
it should be applied not only in white but in light tints as well. 
Light tints, such as pea green, sky blue and light cream, are 
suggested. Incipient chalking of a white paint is not readily 
noticed, but chalking of the same paint tinted causes an accu- 
mulation of the white chalked pigment on the surface, which 
obscures the tint and gives a faded appearance. The real 
reason for this ‘‘fading’’ is due to a change in optical proper- 
ties, such as refractive index, caused by the destruction of the 
linseed oil at the surface. Thus, for instance, it is well known 
that a dry white pigment tinted with dry color has a soft, dull 
appearance compared to the same product wet with linseed 
oil, which develops a brighter and more distinct color. A 
white paint base, to be entirely satisfactory, must be one which 
will tolerate tinting without showing marked fading upon 
exposure. 


Effect of Climatic Conditions.—If possible, the tests should 
be exposed under two or more different climatic conditions. 
Thus, for instance, some paints which may weather quite well 
in the southern part of the country where high humidity and 
high temperature prevail might show cracking due to lack of 
distensibility, in the drier northern section of the country 
where rapid changes in temperature occur in winter months. 
Similarly, some paints which wear well in the northern region 
might chalk too rapidly in the southern region, due to the 
effects of continued strong sunlight. When ultraviolet light 
strikes a film, part of it may be transmitted, part may be 
absorbed, and part may be reflected. If 100 per cent of the 
ultraviolet light is transmitted, the film should remain in 


Exposure Tests 


et 


FIGuRE 133 


Experimental Paints Exposed in Florida for less than 2 years upon boards 4 
unprotected on the backs except for 1 thin coat of White Paint such as was — 
used upon the face of the boards. Admittance of water from back causéd crack- 
ing and sealing 


¢ 
<s 
such as would not occur upon the frame siding of a dw elling, + 


po: ree Aa 


' Es 


Exposure Tests 351 


excellent condition for a long period of time. If, however, 
part of the ultraviolet light is absorbed, it is changed into 
ehemical energy and results in reactions in the film, which 
cause early decay. If a paint contains a pigment which is 
transparent to ultraviolet light, the hght may either pass 
through the film entirely or be partially absorbed in the form 
of chemical energy which may disrupt the film. If the paint 
contains a pigment which is opaque to ultraviolet light the 
light does not affect the liquid in which the pigment is ground, 
and the pigment therefore acts as a protective of the liquid. 
It has been suggested that zine oxide, for instance, because of 
its high opacity to ultraviolet light, acts as a protective to 
paint films in this manner. 


Number of Panels—Wherever possible, panels should be 
exposed in duplicate, or, as an alternative, boards should be 
used which would: be of sufficient size to show differing char- 
acteristics in the same species of wood. If the test is to be 
a very thorough one, flat grain and edge grain wood might be 
selected. One method which has been used to advantage in 
exposing metallic paints might be adopted upon wooden 
panels. Thus, for instance, a large metal surface is marked 
off into two surfaces of equal area. Upon one side the stand- 
ard paint is always applied and upon the adjoining section the 
paint under test is applied. Thus, the two paints, being upon 
the same specimen, should give results which can easily be 
compared. Similarly, a board of sufficient width or a panel 
of sufficient length to show the irregularities or abnormalities 
of wood, might be used. Upon one side the standard. paint 
could be applied, while the adjoining area could be coated 
with the test paint. This could be done without a special 
primer if the object is to show the ability of a paint to wear 
well over any species or grade of lumber. 


Inspections.—Examination of the tests should preferably 
be made every three months. <A record of the results on a 
blank form should be made at least every year, and preferably 
every six months. The inspection can be made in accordance 
with the standards of the American Society for Testing Ma- 
terials, which are given below. The method of rating gloss, 
which heretofore has been largely based upon visual examina- 
tion, can be determined on removable panels with the Inger- 
soll glarimeter. 


wie Exposure Tests 


Primer Paint for Tests——As has been referred to above, 
the failure of many paints upon wooden surfaces is very often 
due to the character of the wood, the moisture content, and 
to the absorption and elimination of moisture by unprimed 
or poorly primed surfaces. These conditions can be very 
largely prevented by the use of a metallic primer. Some of 
the primers that have given excellent service for this purpose 
are given below: 


RED LEAD PRIMER NO. 1 


Red Leadie. icc uc. eels wees «suo on eile Oe 100 ~—s lbs 
Raw Linseed Oil... 6... coe a ce oo a eeleere ore ae 15. Ths 
Turpentine: 0.26 6.5000 6 swols «us wb 0 olla een 2 Ibs 
0) ol :) ern RP i Sib, 


Zine Dust ». 2... cewh wake ecb cle wae ule cree 45. Ibs. 


Bin OXIde os cc. oceis ss 5 ee ule «a le) ene 20 sibs. 
Boiled Linseed Oil ........ 5020.0 bos seen 25 Ibs. - 
Turpentine foci sce cwe coves ude 5 5ie oie een 6 Ibs. 
| Oe (:) EPP 4 Ibs. 


ALUMINUM PRIMER NO. 3 


Tung Oil Spar Varnish (Long Oj!) 7..72..90 ee 5 - Tbs, 
Boiled Linseed. Oil. i. 60.4... 0 os os bee 17th 
Turpentine ©. 0... << ssw us ulna ee tn eee 1 AB. 
Aluminum Powder ... 0.01.0. sces «sks See 1% Ibs. 


Red Lead ...6..0se.000c enced eos onus Otten 12 Ibs: 
Aine “Dust 3... ssG sce eee Seb ww te ce eee Eee ee 2 Ths 
Aluminum Powder ..........<0% © 2s pagers | 
Linseed Of] ...% .neeces vs cen sy 6 5lpnel eee enn 2 = ats. 
Boiled Linseed Oil .....:...%.<. «5 «20 ble 1 ee 
Turpentine 2666 sean i see a ewe oe nies eee ee 1: pS 
Turpentine Liquid Drier ......2..455 252 % gill 


Of these primers, the writer prefers the last one, inasmuch 
as it produces an extremely flexible film of the desired degree 
of hardness and water resisting properties. While it is true 
that an aluminum primer alone has given satisfactory service, 
this product is generally made with spar varnish which tends 
to become brittle after a number of years. If boiled linseed 
oil or heat-treated oils are used in such paints, the drying 
time is so retarded by the aluminum powder that it may be- 
come unsatisfactory as a primer. The use of red lead with 
the linseed oil-aluminum powder mixture gives to the film a 
quick drying characteristic, soundness, and pore-filling prop- 
erty that seems to be extremely desirable. The addition of 


Exposure Tests whi! 


the zine dust, which can be added to a paint in concentration 
without greatly increasing the body, has also proved desir- 
able. It would also appear from the results of some storage 
tests upon this tri-metal type of primer paint that it will re- 
main in usable form for several months, without showing 
hardening. Thus, for instance, a comparison was made over 
a period of four months of a stored red lead paint containing 
30 pounds of red lead per gallon of linseed oil and Formula 
No. 4 as shown above. The straight red lead paint in the 
period referred to had become stiff and almost unusable, 
whereas Formula No. 4 remained soft and easily brushable. 
This might suggest experiments in the direction of the pro- 
duction of a red lead primer of this character, which could be 
kept in prepared form for long periods and used not only 
upon wooden surfaces but also upon all metal surfaces where 
it has extremely desirable properties as a rust preventive. — 


In order to secure information as to the relative absorp- 
tion of moisture by panels primed with aluminum and with 
the tri-metal type of primer, a series of tests were made upon 
one foot square panels of red cedar siding which had been 
brought to a uniform condition. Some of the panels were 
exposed without primers. Others had one coat of aluminum 
paint No. 3 and others had one coat of primer No. 4. After. 
exposure on the roof for 24 hours, during which there was 
a rain storm lasting two hours, the plain panel absorbed 8%, 
the aluminum panel 1.7%, and the panel primed with the tri- 
metal primer No. 4, 1.4% of moisture. After drying the 
panels upon the roof for a period of two days, they were 
sprayed with water for a period of 8 hours. The plain panels 
absorbed from 13% to 18% of water. Those coated with 
Primers Nos. 3 and 4 absorbed less than 3%. It can readily 
be seen from the above that by limiting the amount of water 
that can get into a panel to as low as 3%, it is possible to pre- 
vent great volume changes in the wood. It is also apparent 
that the tri-metal primer is quite as effective as the aluminum 
primer. | 


A. 8. T. M. Method for Reporting Condition of Exposure Tests—It is im- 
portant that uniform, precise and relatively accurate methods for describing: 
or measuring the character and amount of disintegration of paint coats be 
adopted. Unless such standards are evolved, reports made on the wearing: 
yalues of paints by different investigators or observers cannot be intelligently 
or accurately compared. 


354 Exposure Tests 


In considering the adoption of definitions for terms generally used in report- 
ing condition of painted surfaces, descriptive words now in common use have 
been adhered to. In addition, an effort has been made to assign numerical 
values to these descriptive terms with the idea of ultimately working out some 
scheme whereby paint tests may be given a definite rating. A great deal of 
study is still required in order to assign values to the descriptive terms, so 
that the final rating may not only be an accurate one, but that it may really 
represent some well-balanced and understandable relative measure of service 
value. 


Checking.—Checking describes slight breaks in the paint coat which do not 
extend through to the surface painted. This is reported and rated as: 


ADSONE og 5c bs doe Sou soaie’ e's be picasa ate Saree os ete 10.0 

Very Slight oo. occas ce eco ay 0s om aillele oe 9.9 to 8.0 
Slight . i.'6.40 ks e's oe w hae © ok eo ee 7.9 to 6.0 
Considerable | ...c:66 6 + a0 .o-4 ms ecnus a9 sole sien 5.9 to 4.0 
1$1:1) Ere eS here $9200 20 
Very Bad asic acs oon bes asco shales 0's anes aie eee 1.9 to 0.0 


Alligatoring.—Alligatoring describes an aggravated form of checking. The 
breaks in the paint coat are wider than in checking and usually extend almost 
through to the surface painted. While the condition is seldom observed, it is 
advisable to include the term “Alligatoring” in the list of definitions. This 
condition is reported and rated same as for “checking.” 


Cracking.—Cracking describes a break which extends down to the surface 
painted. It may be a break which immediately extends down to the surface 
painted or it may be the development of what was first checking or 
alligatoring. 

On wood, cracking is usually parallel with the grain, although sometimes 
it is at right angles to the grain. This condition is reported and rated same 
as for ‘‘checking.” 


Flaking.—Flaking describes the falling away of small pieces of the paint 
coat. This type of disintegration is generally the result of checking which 
gradually develops into cracking, ending in the crumbling of the paint coat. 
This condition is reported and rated same as for “checking.” 

Scaling —Scaling describes the breaking away of pieces of paint of con- 
siderable size. This condition is generally the result of long cracks, on wood, 
usually parallel with the grain. This condition is reported and rated same 
as for “checking.” 

Blistering.—Blistering describes a condition where the paint coat is de 
tached and raised from the surface over which it is applied, due to the forma- 
tion of gases beneath the coating, influenced generally by moisture behind the 
coating. 

The breaking of the blister results in peeling of the paint coat. 

Peeling.—Peeling describes the pulling away or falling away of large pieces 
of the paint coat from the surface to which it was applied. 

Peeling of paint is not the result of natural wear, but is due to improper 
application or to adverse conditions at the time of painting, such as moisture 
behind the paint coat or a faulty application of the priming coat. 

Gtoss.—Although much depends upon the nature of the coat, it is not advis- 
able to report condition of gloss after a paint has weathered for more than @ 


Exposure Tests OS 


year. The gloss which a paint had shortly after its application disappears 
in proportion to the chalking of the paint, and while it is possible to restore 
a gloss to a surface in some cases, by rubbing, the gloss restored is the result 
of abnormal treatment. Gloss may be reported as: 


MRT Otero Winey odio sis\e cd ue eas ves ceeess 10.0 ; 
eta. Sipla c's cc. ¢ eves 04 008 Une es 0 0 9.9 to 8.0 
EE are eet, 6 a0e Bice oo ois plas Se els eye oe 8% 7.9 to 6.0 
te ig alu crsia bic clas «sis'é vo se aenscceae 5.9 to 4.0 
TI fine ayes. 5s ce Hew sb 3 tok 06 eed eee es 3.9 to 2.0 
ee i cass se fee ce ees lseveweases 1.9 to 0.0 


Chalking.—Chalking describes the reduction of the outer surface of the 
paint coat to a powdery substance, which may be removed by rubbing the 
coating with the dry finger, or a piece of soft, dark colored cloth, preferably 
black velvet. This condition is reported as follows: 


Absent Considerable 
/ Very Slight Heavy 
Slight Very Heavy 


It is a difficult matter to assign uniformly satisfactory ratings to the quali- 
fying terms and, therefore, while the report should include the item of 
“chalking,” it is considered advisable to eliminate ratings. 

Hiding.—Hiding is judged entirely by the degree of concealment of the 
surface painted. This property is frequently referred to as “covering” which 
more correctly applies to the area over which a given amount of paint will 
spread. Hiding is reported as follows: 


SOU yee lays t bp sone vie soa 0ve 00 60 tse 6 06 400 10.0 

MEI ae ac so sia ss cee s cs ces cede swede 9.9 to 8.0 
EN eS Fi aa oie e's do ois oleic eo vee bwecteees 7.9 to 6.0 
eS 5 Sle eG. u wb 6b bela ele aie ecm 5.9 to 4.0 
RM ee Sets ok ee ee a vis ee tee eee ees 3.0 to 2.0 
MINUET Eee 2. lg is cole ese te Ce eae dea oe Mos 1.9 to 0.0 


Color.—Paints are divided into three classes, whites, tints, and colors. 
The degree of whiteness determines the character of report for the first class. 
Two things generally influence color; first, the hiding power, and second, 
chalking. Invariably a paint that chalks presents a better color than one 
that does not. The impression gained through the eye serves as the basis for 
report regarding the color of paint. The original appearance need not be 
considered. While all colors show a natural fading out, some retain a pleas- 
ing tone while others appear distinctly muddy or lack the brilliance shown 
when first applied. The terms used for reporting color are: 


Very Good Poor 
Good Very Poor 
Medium 


It is not considered advisable to assign rating to the descriptive terms. 

General Appearance.—The general appearance of painted surfaces can 
really be determined only by viewing them from a distance of twenty or thirty 
feet, with the idea of forming an opinion as to whether the appearance is 
good, which will be influenced by such conditions as cracking, scaling, chalk- 
ing, and other conditions usually found in paint wear. 


356 Exposure Tests 


Forest Products Laboratory Tests on Painting Lumber.— — 
Extensive exposure tests have been conducted by the Forest 
Products Laboratory in practically all climates represented — 
in the United States. In these tests eighteen different kinds — 
of soft woods in edge grain and flat grain were exposed at — 


ai et Sige ea iets Meares rt 5: 


pioneers pebben naar 


FIGurRE 134 


An early stage in the development of paint slits. 
(Magnification about 2 diam.) 


eleven different exposure stations. They were painted with — 
two different types of paint, including pure white lead and a 
paint containing 60% white lead, 30% zine oxide, and 10% 
inert pigment, Some of the results of these exposure tests — 


JOT 


Exposure Tests 


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Lt 9S 66 VS 61 09 SP” "Conofren} DONSjopNasd) AY Se[snod 
SL 66 LI TP OL 62 SF ttt ts (40209U00 sa1gyV) AQ 2M 
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5 GG G S&S 0 6 2 ee wae (DUDIqAIQUD] SNu_) 2UId IBsNg 
at && OT LY as pe OL 98 (Vsosapuod sniig) ould MOT[eA U1981S9A4 
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358 


Exposure Tests 359 
denne ee ee 
are shown in Figures 134 to 136. For a detailed consideration 
of these tests, reference should be made to the original re- 
port.* Two of the interesting charts appearing in this origi- 
nal report are presented as Tables 48 and 49. 


FIGuRE 135 


Discoloration of a paint coating at Gainesville, Fla., due to the growth 
of lichen and sooty mold. It is claimed that by using less linseed oil and 
more turpentine in the third coat paint for such climates the danger of 
) 9 alee ia of this kind can be very greatly reduced. (Magnification about 

diam. ) 


* “Painting Characteristics of Woods,” by F. L. Browne. Scien. Sec. 
Cire. No. 219. 


360 Exposure Tests 


by 
FER NRE 


FIGURE 136 = 


The paint coating tearing loose from the wood in long shreds in the veryia 
dry climate of Tucson, Ariz. The long slivers appearing in the photograph 
are pieces of the paint film, not of the wood. . ie 


one 


Exposure Tests 361 


FIGURE 137 


Section of the Forest Products Test Fence at Gainesville. Panels on left 
coated with white lead show more fungus growth than those of Lead-Zinc 
Paint on right. This test shows importance of conducting tests in various 
localities in order to subject paints to local conditions. 


362 Exposure Tests 


Service Tests on Varnishes.—During the past few years, a 
committee, of which the writer has been chairman, has con- 
ducted a series of exposure tests on varnishes. ‘These are 
fully outlined in the Proceedings of the American Society for 
Testing Materials for 1925 and 1926. Included in these tests 
were maple panels, black japanned panels, plain black iron 
panels, and glass panels. The black japan used for priming 
the panels was an automobile fender enamel baked for 46 
minutes at 450° F. After application it was rubbed with 
pumice stone and water. It was believed that one might ob- 
tain the maximum life of long or short oil varnishes upon such 
japanned panels up to the time of the first cracking of the 
varnish. It was found as a result of these tests, which were 
exposed under the same conditions and for the same period 
of time in different parts of the country, that the reports 
were all in agreement in so far as the elimination of wood 
and glass panels was concerned. These did not give uniform 
results. The black japanned and black iron panels, however, 
gave fairly consistent results. The exposures over some of 
the black japanned panels showed a lack of adhesion between 
the japan and the varnish, which might possibly have been 
overcome by baking the japan at a lower temperature. On long 
time exposure, the plain unsurfaced black iron panels showed 
a tendency to rust, which interfered with the inspection. As 
a result of these tests, however, further tests were conducted 
during the past year, in which more permanent types of 
panels (relatively rust-free) were included. These included 
cold rolled steel as well as black iron (having a smooth, ad- 


herent blue mill scale). Similar panels which were finished © 


with a black tung oil spar varnish, subsequently baked, were 
also used. There were also included cold rolled steel and 
black iron panels which were plated in the following manner: 

Nickel film .001 inches. 

Copper film .005 inches, then nickel .0005 inches. 

Chromium film .0004 inches. 

Nickel film .0908 inches, then chromium .0002 inches. 

While results are not available as yet on these panels, the 

indications are that varnishes which crack upon the plated 
panels are more apt to show peeling at the same time than 
varnishes applied to black iron or japanned iron panels. It 
is felt therefore that the latter types of panels are best suited 
for varnish exposures. 


363 


Exposure Tests 


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Exposure Tests 


364 


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AyBoTpVld “ystuy Jo Jaj~varvyo 0} onp ‘Yydeasosorm0.0Yd 
ul UMOYS WIZ jo Suljealays Jusieddy ‘“yvoorspun urdef 
MO][9A ASAO USTUIBA TIO Sun} Burzy[[Vyss19 Jo yoo vuO 


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-I9yIp ‘S[vuvo pepunor ‘deap soytquiesel yeyM YIM ps0B194 
“UT doBjINS aU “ywooTepun uvdef MoT[ef AVAO Jenbovy 
SUTYSIUY aSO[N[[900AI1U AJDOTISBIA MO] ABaTD Jo s71BOD OMT, 


OFT TAOS 


65 


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Exposure Tests 


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m[y YSluIvaA Sutpunoains jo 
JU0) 91R possodxes JusewIsId JO sraar 
MOT[OZ SUTYIIYD I[QBVAIPISUOD “3B0d 


AO YSIUIBA IOL19}X9 JO BOD JUD 


CEL BNO 


FIGURE 144 


Photomicrograph of surface of 
an interior rubbing varnish. Sur- 
face was scratched with a needle. 
Note clean cut effect due to hard 


film. 


FIGurE 146 
Photomicrograph of surface of 
exterior spar varnish. Surface was 
scratched with a needle. Elastic 
and comparatively soft nature of 
film indicated. Also note dark 
spots due to particles of  poly- 
merized oil that have become in- 
soluble. These particles are often 
the cause of a “sandy” surface. 


Exposure Tests 


FIGURE 145 

Photomicrograph of surface o 
an exterior spar varnish. White, 
cloudy effect caused by immersion 
in cold water. Water has not 
abraded or injured film but has 


possibly formed an emulsion with 
the outer layer. 


FIGURE 147 


Photomicrograph of surface of — 
an interior oil coating showing — 
effect of boiling water which has — 
caused the film to “creep” or pull — 
away from the surface, leaving — 
crater-like bare spots. To the | 
naked eye a white and rough sur- 
face is indicated. 


Exposure Tests 367 


FIGURE 148 


Photomicrograph of surface of 
an oil coating that has shown 
peculiar crinkling, probably due to 
surface tension effects. 


FIGURE 150 


Photomicrograph of a drawn 
metal article. Note abraded effect 
of metal. Rapid corrosion would 
follow unless protected with paint 
or varnish. 


FIGuRE 149 


Photomicrograph of a paint 
coating. Thinner used in the paint 
was too volatile. Upon evapora- 
tion from film, it caused formation 
of small craters. 


Figure 151 


Photomicrograph of a paint coat- 
ing. Paint was not properly ground 
in mill. Note rough, granular sur- 
face of unground pigment particles. 


368 Exposure Tests 


FIGURE 153 


FIGURE 152 
Photomicrograph of a wall coat- Photomicrograph of an experi- 
ing. Drying in a dusty room mental flat coating. Paint con- 
caused adherence of dust particles. 
a darkened 


tained too much volatile matter, 
These gave surface Scratch made with a metal point 
shows dry nature of film. 


appearance. 


FIGURE 154 


Photomicrograph of a cross-sec- 
tion of an enamel coating on oil- 
cloth. Note warp and filling 
threads of cotton fabric, filled sur- 
face, and smooth outer’ white 
enamel film. 


Exposure Tests 369 


Testing the Rust Inhibitive Value of Pigments for Metal 
Paints.—In some fairly comprehensive tests carried out by 
the writer in 1908 in Atlantic City, under the auspices of the 
A. S. T. M., several hundred steel and iron panels 18 x 36 
inches and of 18 gauge were employed. In this test the 
specific gravity of the pigments was determined, and a defi- 
nite formula for the grinding was then decided upon, so that 
the same amount by volume of each pigment would be used 
with the same quantity of oil, viz., specific gravity of pigment 
X 3 = lbs. of pigment to gallon of oil. The pigments were 
ground separately in a mixture of two-thirds raw and one- 
third boiled linseed oil, no drier or thinners being added, be- 


CONDITION OF PAINTS. AFTER FOUR YEARS’ EXPOSURE. 
Rating 


1913 

Panel Pigment 
MEV CTINIION ook ecg cee ce ce ete ve ch tee veateneas 9.8 
Demeromemie edd CHTOMUte 26.6. we ec ccc cee ee ete 8.3 
TON Q UG oo ae vce ee cc ew sce ve wes a eeecuveses 8.0 
CS AFCOAL, fs... so cp ka ee ec eek eevee ete e es tuewess 7.9 
Been tarium Chromate ....... 2.2.02. ese een eee etes 7.8 
Rete gC XING on. ee cca b eee eee w ed cuuduceteucs 7.8 
4] eT et LIE TOTLC). 6... ccc cee eek oo e bulee eee ecauss 7.6 
5)  Sublimed Blue Lead (Basic Sulfate—-Blue Lead)............ 2 
eee orpeneeiack (natural barytes) ...........0..00.00 een ae 6.8 
SV. ac ee bcs Po be Wee tdewbeeeecuereaie 6.7 
Ne ON PY, oo ewe cle cw ee cece eee ewe ceuuedubaces 6.3 
MIE ITG ee ccs wine Bee vee ct te tedeweties Es 
SunrrarectmeeMetallic: BOW ......- 2. cee ee ewe eee cee eceeeses 6.1 
IPMN MMICTIM AVI TCA oo... es ln wc cw eee cece cen sccescsecaswe 5.9 
Ge elljw. OCHKC. ..... 00. cece cde e nce eevee etue wentwoee De 
eee Tirome. YELLOW ...-.... 00s decccpceecewawevneedue n2 
ET Dh ks ccs a ck vieen rsp ce edueg gen daeeuawes 5.1 
ME ee, cok. dw taney cy wc wees ae bole aewaat 5.0 
SS 6 iy rr rr re 4.5 
DEIR TC OAEVECS) 0. ic ce esc cee ceed eaebccdwavauives 4.2 
Peewee Qranze Mineral—980% Pb,O, ....2..-.0-.use cnc ees 4.0 
IN AE ls eek es ce ced caucelevieectious Bio 
IEE EQUIPO wo heck co Wace casceheavega vasckuncds 2.6 
1 Semester OCeee eV Hite Lead. oo .2. ec ec ce ce etl bn veces cen nes Lo 
meme reece White LOA)... .....- ec cc cccscee ceseceucevcce ‘bee 
I SSVI)... 0 ose lec cs oct cde ccwecsvccciacaat Ne: 
memaevedine (magnesium silicate) .............cececccccccucccs A Mee 
MR ro he esos kd selec b A ve ve ba ede k eels 0.8 
IT es sg cine sin bok ek Queled vale lon cdelaweas 0.4 
ME MINCE POUL ELATVLOS oc, 0. fs caia wc bse a bicndaevbaecebiccsonennun 0.2 
MITER ACO) 2s os cs eine wn vod Sb els wow baa ee Obece 0.2 
MEMEMISIUEAPVIPS 0. ws. cin ace enss cc ccs eavictlbacccleecsecene 0.1 
Seater Carbonate (whiting)  ........c....cene vec caventeccn 0.0 
meeeetcinm Carbonate (precipitated) ......s.0+.c.cscacececccce 0.0 
MINER TRIO BUC. bos k hci > ove eos bs baba vcvldavcdhadhen 0.0 


* Contained about 7 parts Barytes to 1 part Black by weight. 


370 Exposure Tests 


cause of the unknown factors which would be introduced by 
the drier content.* 


The paints were all applied at a definite spreading rate of 
900 square feet per gallon on three types of iron or steel. 


At the end of four years, certain definite results were 4 
shown, the report of the committee as of the fourth annual — 
inspection being presented below, 10 being the highest rating, 
zero the lowest. 


FIGURE 155 


Members of Educational Bureau and Inspection Committee at 
Atlantic City Panel Tests during spring of 1910. In these tests 300 
steel and iron panels 18” x 36” in size were used. The use of panels 
of such large size affords a more practical “brush-out” test than 


where small panels are used. For details of test see Scientific Section 
Circular No. 202. 


* The above method gave satisfactory paints in almost all instances. With 
zine oxide, however, the paste was so thick that it was necessary to add 170 
grams of turpentine to 1000 grams of paint to bring the paint to working ~ 
consistency. This feature, together with the low oil content of the paint, 
was no doubt responsible for the relatively poor showing of this pigment 
which requires a long oil reduction in order to obtain satisfactory service. 
Similarly with bright red oxide, the addition of turpentine was required. 


Exposure Tests 371 


FIGURE 156 


Type of construction used in Atlantic City, Pittsburgh and North 
Dakota tests made several years ago. Modern tests should have panels 
at 45° to the vertical to accelerate exposure. 


FicurE 157 


Old panel exposure tests back of laboratory. 


Preparing Metal for Painting —Sub-Committee XIV on 
Preparation of Iron and Steel Surfaces for Painting, of the 
American Society for Testing Materials, exposed a series of 
panels during February 1917, to determine the difference in 
wearing properties of paints upon steel surfaces prepared by 
different methods. The tests were exposed at Altoona, Pa., 
and Brooklyn, N. Y. <A preliminary report of the Committee, 
presented in the 1921 Proceedings of the Society, contained 
the following statements: 


372 


Exposure Tests 


‘‘While the tests are not completed and final concly- 
sions are not offered at this time, there are certain in- 


dications that are matters of such importance that it | 


seems desirable to report them. These are the follow- 
ing 

“1. The thorough methods of preparation, 7. e., sand 
blasting and pickling, show no superiority in general over 


ordinary methods of cleaning the surface by scraping, — 


wire brushing and wiping, where corrosion has not com- 
menced or has only moderately advanced. This applies 
to both new steel and old steel which has been in service. 
Test No. 10 indicates that where corrosion has advanced 
greatly, ordinary methods do not give satisfactory re- 
sults. 

‘*2. Weathering to permit loosening ‘and partial re- 
moving of mill scale, with ordinary methods of cleaning 
before painting, is detrimental to preservation. 

“3. Painting in a cold dry atmosphere results in pres- 
ervation as good as painting in warm dry atmosphere, or 
on heated steel. (This may be due to the greater thick- 
hess of coatings applied in the cold atmosphere. See 
spreading record of coatings.) The appearance of the 
coating may be impaired by shriveling and wrinkling. 

‘4, That sand blast cleaning may give better results 
than pickling is indicated by the panels exposed at Brook- 
lyn. There is no appreciable difference observable in 
the panels treated by the two methods and exposed at 
Altoona. | | 

‘‘o. The exposure of sand blasted and pickled surfaces 
for the development of incipient rusting before painting 
may be detrimental rather than beneficial, as indicated 
by the results of test of pickled plate at Brooklyn. 

‘6. The preparation of old painted steel surfaces 


which have bare rusted spots, by brush coating with ben- — 


zine over and around the rust spots, burning the benzine 
off and then scraping and wire brushing, gives better re- 
sults than scraping and wire brushing without the benzine 
treatment. Where any considerable amount of surface 
requires treatment, the comparative cost of the method 
and of sand blasting should be considered. 

“7. There is no difference observable in the results of 
the application of the same methods to old and to new 
steel.’’ 


Apparently more positive results were obtained at Brook- 
lyn than at Altoona, the report of the fifth inspection, as of 


Oe eer 


Exposure Tests 373 


Noy. 25, 1922, being appended hereto. While no positive 
conclusions have been drawn in connection with these tests, 
the information presented will doubtless be of interest to those 
having to do with the application of protective coatings. 


TEST ON NEW STEEL, BROOKLYN 
Description 


Rating 
Panel No. 1. Clean ‘surface, mill BOLIGIINT ACL hs BAeea teeta taut. 60 per cent 
“No. 2. Mill scale broken; some rust; hand cleaned...... 40 %: 
_ No, 3. Sand blasted } 50 re 
“No. 4. Sand blasted | Various conditions of atmosphere | 25 a 
“No. 5. Sand blasted and temperature at time 40 re 
“No. 6. Sand blasted of painting 80 ke 
| 2 $0... 7.* Sand blasted | 60 Ke 
Panel No. 16. Incompletely sand blasted.............. hannah 65 per cent 
ree SS, Pickled, hot water rinsed, neutralized, water 
TS ya i ee a Rg 60 % 
~~ Mo, Qo* Pickled, cleaned as for Panel NOMS awe ae Eon 2 
olen ae Pickled, washed with cold water under pressure. 25 a 
TEST ON OLD STEEL, BROOKLYN 
Description Rating 
Panel No. 12. Cleaned with ‘idle 2S ELV IRE eae le cae (Re 40 per cent 
“ No. 13. Cleaned with benzine, scraper and wire brush. He ot) - 
No. 14. Benzine applied and burned with torch; cleaned 
with scraper and wire brush................ 80 ¢ 
See etd blasted 2... tt 40 3 


In the 1926 report of this Committee, the ratings of the 
panels were given. Among these ratings were the following 
which were obtained upon new steel panels, surface treated 
in various fashions. A rating of 100 is highest, a rating of 0 
being complete failure. 


CONDITION 

RATING 

PER CENT 

OCTOBER 

PANEL SURFACE CONDITION oR TREATMENT BEFORE PAINTING 15, 1925 


NEW STEEL PANELS. 


No.1 Clean surface, mill scale intact, painted in warm dry room 10 
No. 2. Mill seale broken, some rust, hand cleaned, painted in warm 
MEM s ee he i ee ene pa 
No. 3 Sand-blasted, painted immediately after in warm dry room . 80 
No. 4 Sand-blasted, heated in oven to 225° F. and then painted.. 35 
No. 5  Sand-blasted, placed in cool damp room 40 minutes and 
MME ee rete Gh coi. Spy Sh he Wee eee: 84 
No. 6  Sand-:blasted, placed outdoors and painted there at a 
ReemeerrresOt: Ob ety O77 We le ie 84 
No. 7 Sand-blasted, exposed out of doors for 7 days, painted over 
Meme ar ITY TOO) |. m4 oc Sas bck cen oo ks 55 
No. 8 Pickled, painted in’ warm ODWr SOOM elt Cnete teeta ere ee 84 
No. 9 Pickled, exposed out of doors 7 days, painted over rust in 
REM OO on girly nga cus hgh oalhe edie ive c ek waa hy ees 50 


*Seven days’ exposure to weather before painting. 


374 Exposure Tests 


Testing Metals With an Accelerated Roof Exposure Tank.— 
A type of test devised by the writer for determining the re- 
sistance of plain, galvanized, and painted iron conductor 
pipes such as are used for rain spouts and leaders upon build- 
ings, is shown in Fig. 158. It consists of a large metal tank, 
96° long, 25" wide, and 9” high, constructed of galvanized 
iron and thickly coated on the inside and outside with a heavy 
coating of acid resisting bituminous paint. On one side of 
the inner surface is placed a wooden rack eut out to serve as 
a support for the pipe or other test specimens. This rack is 
so arranged that when the specimens are placed in the tanks 


FIGURE 158 


View of tank tests on roof, showing painted pipes semi-submerged 
at angle in corrosive liquids. 


and the tanks filled with liquid within an inch of the top, one- 
half the inside and one-half the outside of each pipe will be 
submerged at an angle, the other half being exposed to the 
air. To accelerate this test, cut-up sections of asphalt shin- 
gles of various kinds and a series of red cedar and cypress 
shingle splinters about 6” long and %” wide, are submerged in 


Expcsure Tests 375 


bundles. Continuous leaching action of the water upon these 
splinters will to some extent duplicate the formation of sub- 
stances which would be evolved from roofs by rain water. 
Metals exposed under these conditions, especially when salt 
water is used in the tank, corrode with great rapidity. A 
few of the specimens exposed, together with a chart of some 
of the results obtained, are shown below: 


FIGURE 159 


View of exterior of No. 1 Unpainted and Nos. 2, 8 and 9 Painted pipes that 

were in accelerated salt water test. Note how corrosion has occured mostly 

at the water line where air is absorbed by the salt water and greatly stimu- 
lates its corrosive nature. Note that uncoated specimen is most affected. 


376 Exposure Tests 
TE 
TABLE 50 


THIS GROUP WAS IN SALT WATER FROM MAY 19 TO AUG. 19. 

Ses innnevunir tres cn smc ents 
Pipe 

Section Inspection Report 
No. 

nnn earn enema 

N-1 Very badly pitted and corroded at water 
junction. Most severe corrosion on 
exterior surface. Zine gone from sub- 
merged section. 

B-1 Same as N-l. 

N-2 Very slight rust at a few small spots on 

Black Asphaltum—Tung exterior. Inside in excellent genera! 

Oil Paint condition, 

B-2. Same as N-2. 

N-3 Several round rust spots developed at 
water line junction and considerable 
scaling. Metal, however, is in gen- 
erally sound condition. Inside, some 


Treatment 


No Paint 


Aluminum Coal Tar Bitu- failure of paint at water line junc 
mastie Solution tion, but generally sound, excellent con- 
dition. 


B-3 Same as N-3, except slightly more rust 
on exterior than on N-3. 


a aN nee eh 
N-4 Marked corrosion at water line. Other- 


Black Pigmented Spar wise sound. Only moderate corrosion 
Varnish on inside at water line junction. 
B-4 Same as N-4. 


aaa NNN TI Ties innccnr crc 

N-5 A few slight corrosion spots at water 

Aluminum Spar Varnish line. Otherwise sound. Same condi- 
tion inside. 

B-5 Same as N-5. 

N-6 Sharply defined corrosion spots at water 

Red Lead line junction. Slight corrosion on in- 
side. Marked blistering. 

B-6 Same as N-6. 

N-7 A few comparatively slight corrosion 
spots at water line. Considerable blis- 
tering of paint. Otherwise sound. 

Zine Chromate Practically no corrosion inside but much 
blistering of paint. 

B-7 Same as N-7 but conditions more pro- 
nounced. 


N-S Considerable corrosion at water line junc- 
tion on exterior. Inside, moderate cor- 


Zine Dust Primer rosion. Some blistering of film. 
B-8 Same condition as N-8 but slightly more 
pronounced. 


N-9 Well defined corrosion on outside at water 

line. Comparatively no corrosion on 

1 Coat Red Lead and 1 inside. Considerable blistering of film. 

Coat Aluminum Varnish B-9 Same conditions as N-9 but slightly more 
pronounced corrosion. 


N-10 Moderate corrosion on outside at water 
line. Inside, corrosion and slight blis- 
Iron Oxide Paint tering. 
B-10 Same condition as N-10, possibly more 
pronounced. 


Ee, ee 


Exposure Tests S74 


—— Sess 


Testing Toxic Compositions to Prevent Fouling of Steel 
Ships and to Preserve Wood Bottoms.—A resume of four 
years’ research in tests of this character and which included 


FIGURE 160 


View of a very small section of test racks in Beaufort harbor. Members of 
inspection committee pulling up panels and examining them. 


FIGURE 161 


Painting “patch” tests on destroyer. If good results are obtained 

in panel tests, the composition may warrant a “patch” test on a 

small craft before conducting a large size service test upon a 
battleship. 


378 Exposure Tests 

nearly two thousand panels is given in Scientific Section Cir- 
cular No, 259. Briefly stated, the test compositions were usu- 
ally applied to steed panels 12” wide and 18” long, with a 
large hole at the top, through which was placed a ‘‘sister 
hook’? and a rope for suspension. ‘Two holes were made at 
the bottom corners, through which to place wires to suspend 
bricks to act as weights to keep the panels from swaying in 
the water during rough periods. These panels were generally 
submerged to such depths that at ebb tide the surfaces would 
be about two feet below the surface of the water. The type 
of racks from which the panels were suspended is shown in 
Fig. 160. In general, the start of such tests should be made 
early in the spring when the barnacles are just starting to 
run. If the panels are exposed late in the fall, no erowths 
may be obtained in many waters, and the only results indicated 
will be the effect of the salt water upon the coatings and the 
underlying metal surfaces. An exposure of two months in 
June and July in many waters will produce growths which 
could not be developed during the other ten months of the 
year. In making tests of this. character, it is well to select 
exposure locations at widely separated points. ‘Thus in the 
United States, exposure stations where our tests have been 
made have ranged from Atlantic City, N. J., to Beaufort, N. C., 
south to Key West, Fla., on the Atlantic, west to Los Angeles, 
and north to Puget Sound on the Pacific. A chart such as was 
used by the writer for reporting results is given below: 


SPECIMEN REPORT 
SHIP BOTTOM PAINT TESTS 


Number of test plate, C-3. Formula of 

Submerged at Beaufort, N. C. composition 

Date submerged, 8/1/22. 

Weight of liquid paint applied to 2 coats A, C. No, 14. 
standard panel 12/18”: 1st coat, 18 grams | 1 coat A. F. No. 2. 


2d coat, 19 grams | Formula No. 576. 
3d coat, 27 grams | Shellac Paints. 


INSPECTION REPORT 


Date, Nov. 17, 1922 >) Date. comes 1atesscucees Dates nae 

HispeClotinsc. ecu Inspectori....: Inspectot...... Inspectot...... 

Foulitigs< a6 2a Slight, «fs etaduhaecsbecerneenenie anni seen tec ea 
COTTOSIOTE <.ke. Slight, «= - |  _ Pikcaaseosentoneree nt gel ahha a a 
Film condition..| Fair, © _ Pasevecvecyneeteepy cnc ligating en 
Remarks: Light slime, few bar- | Lost, © JoecbecteccceneesssPesseseuspeseeanesn senna 


nacles, rust spots, 
A. F. off few spots, 
soft, washes easily. 


ane, Nn aes NN tele eee ar Sent nove en Dare ne 


Exposure Tests 379 


Conditions to report on fouling and corrosion: None 

Cee Shght 
Moderate 
Cons.derable 
Heavy 

On film condition: Excellent 
Good 
Fair 
Poor 


Bad 


‘BEAUFORT. N.C. MAR. 1923 


FIGURE 162 


478—Rosin-rubber compound. 484—Rosin-rubber 

compound containing arsenic, copper, and mercury 

toxics and Titanox and zine oxide exposed one 

year. 442—Rubber latex coating exposed four 

months. 475—Hot plastic green soap compound 
exposed one year 


380 Exposure Tests 


Testing Copper Paints.—In determining the toxic value of 
copper paints to be used as preservatives for wooden ships 
and for wooden piling, slats 34" thick, 12 feet long and 3” 
wide, may be selected. The wood may be given two coats of 
the toxic preparation, and be submerged so that one-half of 


FIGURE 163 


First series of teredo test panels after exposure. 


the panel is exposed to the air. By this type of exposure, 
very Severe results may be obtained at the water line. After 
exposure for a few months, the panels may be removed and 
sawed in sections to determine whether teredo or limnoria 
have been admitted. 


aM 


Exposure Tests 381 


FIGURE 164 


Cross-sections of first series of teredo panels after test. 


Testing Protective Coatings Upon Aluminum Alloy Sur- 
faces—In Figures 165 and 166 are shown a few of the test 
racks exposed by the writer at Washington, D. C., and at 
Hampton Roads, Va., for determining the durability of vari- 
ous protective coatings upon steel and upon aluminum and 
magnesium alloys. It will be noted that the panels, which 
are 6 x 12 in size and approximately 18 gauge, were placed in 
wooden racks with wooden flanges at top and bottom to pre- 
vent any contact with other metals. In the Hampton Roads 
exposure, the panels were tied to metal I-beams and exposed 
at an angle of 45° to the vertical, approximately six feet above 
flood tide. It was thought that this exposure would be an 
extremely severe one on account of the salt spray dashed 
against the panels in rough weather. The results on some 
of these panels are indicated in the photographs. It was 
found that while as a rule paints which give adequate pro- 
tection to steel surfaces are also useful upon aluminum and 
other light alloys, the coatings to use on the latter metals 
should be extremely elastic. Coatings made with nitrocellu- 


382 Exposure Tests 


lose lacquers (applied directly to the metal) or with varnishes 
do not withstand the tremendous stresses set up by the expan- 
sion and contraction of these alloys, whereas linseed oil coat- 
ings have proved entirely watiaranioue 


It will be noted in these tests that there were included a 
series of tensile strength specimens upon which physical tests 
had been made previous to exposure. These specimens can 
be removed from the rack every three months and the tensile 
strength and elongation again determined. It is considered 
that such a method of test is an important one where light 


FIGURE 165 


Exposure tests on coated duralumin panels over surface of ocean at Hampton 
Roads, Va. 


alloys are coneerned, as it has been indicated that exposure 
to salt water, while not apparently affecting the surface at 
first, may cause intererystalline embrittlement of a very seri- 
ous nature. Such embrittlement is not usually indicated by 
the surface appearance of the specimens. Photomicrographie 
examination and. X-ray tests are important where” a Com pIER 
study of the subject is considered. 


383 


Exposure Tests 


‘UOJSUIYSVAA JB S80} JOOr poiedofaoV AOT[V wUNUTUIN]B IOJ YowVs 4sSay, 


QOT TINO 


384 Exposure Tests 


SOA OG SOE A I NG: AION: Na 8 A IT 


' 
; 
E 


FIGURE 167 
Panels from Washington tests. 


16 Steel—Aluminum Paint A. Very good. 

17 Steel—Aluminum Paint B. Considerable rust. 

18 Steel Aluminum Paint C—Very heavy alligatoring and dark 
surface. 

23 Duralumin—Coal Tar Varnish Paint. Very heavy scaling. 

23 Steel—Coal Tar Varnish Paint. Sound. This indicates the fact 
that varnish paints upon steel may be durable, but when ap- 
plied to duralumin they rapidly flake off. 


BD 18 Duralumin—<Aluminum Paint C. Heavy alligatoring. Dark. 


Exposure Tests 385 


FIGURE 168 


Panels from Washington tests. 


19 Duralumin. Red Lead Primer. Excellent. 

20 Duralumin. Zine Chromate Primer. Excellent. 
21 Duralumin. Zine Dust Primer. Excellent. 

22 Duralumin. Titanox-Zine Primer. Excellent. 


All these four paints, made with linseed oil, have given excellent 
adherence and show no flaking. 


5 Duralumin. Green Nitro-Lacquer. Dull; good except for tiny 
scales. 
7 Duralumin. Black Asphaltum Varnish. Scaled; rusty. 
9 Duralumin. Air Drying Japan. Checking; dull. Some rust. 
23 Duralumin. Coal Tar Varnish Paint. Heavy scaling. 
These latter four panels, being coated with more brittle paints, 


have not shown the adherence that was given by the linseed oil 
paints. 


er 


386 Exposure Tests | 
Dennen aes, 
TENSILE PROPERTIES OF PANELS TESTED. 

Tensile Properties 
Ultimate Tensile Strength Hlongation (2”) 


Specimen No. lbs. sq. in. per cent 

A l 61,880 22.5 

A:2 61,670 22.0 

As 60,420 a 

A 4 60.620 25 

BJ 58.160 20.5 

pe 58.160 22.0 

B 3 59,740 ; 21.5 : n 
STEEL 

Ald 60,000 19.0 

Pee 65,710 175 

ae 50,430 30.5 

$62 51,280 31.5 


A—Danels from ‘Aircraft Factory. 
B—Tlanels from Bellevue Laboratory. 


Testing Nitrocellulose Lacquers on Metal.—The largest use 
for nitrocellulose lacquers at the present time is upon the 


FIGURE 169 


Roof tests of lacquers and varnishes on writer’s laboratory, showing panels 
45° to the vertical, which nearly doubles the speed of disintegration. Also note 
apparatus for daily spraying panels with water, which also greatly increases 
speed of failure, thus making such tests accelerated roof exposure tests. 


Exposure Tests 387 


metal bodies of automobiles. It is usual, therefore, to employ 
metal panels in testing these lacquers. Automobile fender 
stock panels of any suitable size may be used. The lacquer 
may be sprayed, flowed or spun upon the panel to the desired 
thickness and the panel exposed on the type of rack shown in 
Figure 169. 


Since some lacquers do not adhere tenaciously to metal 
without proper undercoats, it is the procedure in laboratories 
of some lacquer plants to. have made up a large number of 
panels primed and surfaced ready to receive the test lacquer. 
The lacquer is then usually sprayed on under conditions 
closely similating those which obtain in actual shop practice 
where automobiles are finished. Usually, the first defects 
noted on lacquer exposures are chalking, which sometimes 
obseures the color. Small portions of the panels may be 
rubbed from time to time to remove the chalked surface and 
to determine whether the film below is in good condition. 
Observations should also be made to determine whether any 
water ‘‘Spotting’’ is shown. Wherever these tests are made 
there should be included control tests of a standard lacquer 
of the desired color upon which to judge the value of the 
sample under test. (See also chapter 36.) 


Exterior Exposure of Lacquered Wood Panels.—In deter- 
mining the durability of lacquers which have been proposed 
for use upon exterior surfaces, it is generally advisable to 
apply them not only to wooden panels which are unprimed, 
but to panels which have been primed with moisture resisting 
primers which will tend to seal up the surfaces and prevent 
expansion and contraction due to moisture absorption or 
elimination. It is also advisable to apply the lacquers to 
wickerware panels such as are used in the construction of 
porch furniture. Lacquers which may prove useful upon cer- 
tain types of surfaces often scale off wickerware because of 
the great changes in volume of the wicker during moist peri- 
ods. The comparative value of special elastic sealers and 
primers for wickerware may be indicated by such tests. Pan- 
els of this type are shown in Fig. 170. 


Testing Paints for Cement Surfaces ‘by an Accelerated 
Method.—In order to determine in a short period of time the 
relative resistance of paints to the effects of the strongly al- 
kaline surfaces of damp, freshly laid cement and plaster, a 


388 Exposure Tests 


; aN 


(iy {iil 


FIGuRE 170 
Testing Lacquers on Wicker Panels. 


test was designed of a most severe character. It is probably 
several times as severe as the conditions that would obtain in 
actual practice, and therefore may not be termed a normal 
test. Apparently, however, it gives considerable informa- 


Exposure Tests 389 


tion regarding the efficiency of various priming liquids and 
subsequently appled paint coatings. ~The tests are fully de- 
seribed below, .and.the results are charted in detail. The. 
tests were made with painted panels of both Portland cement 
and plaster. 


Making Panels.—The cement panels were made with one 
part Portland cement mixed with two parts of dry sand and 
the usual amount of water. The mixture was poured into 
cake tins approximately 12 x 9, to a depth of 114 inches. The 
tins contained sheets of chicken wire the size of the pan to 
act as reinforcing. After setting for six days, the panels 
were removed from the tins. 


In making the plaster panels, the procedure was to first 
make up cement panels one inch thick of the Portland cement 
sand mixture reinforced with wire. During the drying period, 
the top surface of each was scratched so that good bona’ 
ing properties with the white finish coat could be obtained. 
The white coat was made with ‘‘lime putty’’ prepared by add- 
ing water to hydrate of lime tg produce a paste of medium 
consistency and allowing it to stand over night. To 2 parts 
by volume of this lime putty there was added one part of 
gypsum gauging plaster (hard wall gypsum plaster). This 
was applied to the base panels to a thickness of about 3/8”. 
The making of all panels was done at the laboratory by an 
expert plasterer who had spent about twenty years in the 
trade. 


Priming and Painting Panels—After the manufacture of 
the panels, they were allowed to dry under normal conditions 
for a period of two weeks. The primers (Nos. 2 to 16) were 
then applied in one coat work. After allowing the primers 
one week for drying, the paints (A to H) were applied, in two 
coat work, allowing a period of one week between the drying 
of each coat. A strip about one inch wide at the top of each 
panel was then coated with chrome green paint which is 
rapidly bleached out when in contact with lime compounds 
from cement. The panels were then stencilled with designat- 
ing numbers, dried the usual period and placed in a series 
of pans made of galvanized iron, 126” long, 26” wide, and 1%” 
deep. Hight pans were required to hold the total of 256 
panels in the test. After placing the panels in the pans, 


390 Exposure Tests 


sufficient water was added to each pan so that the water 
would come up to about two-thirds the height of the panels. 


FIGURE 171 
View showing plasterer and assistants preparing plaster panels for the paint tests. 


Heat, Cold and Absorption Tests on Painted Cement.— 
The results of tests such as are outlined above, upon many 
paint compositions, 1s given in Scientific Section Cireular No. 
299. In general this test is extremely severe and causes the 
type of failures shown in the illustrations. Other tests may 


Exposure Tests 391 


be employed, such as a test to determine the water resistance 
of the primed surface. In a test of this sort, the writer has 
used small circular pans filled with the same type of plaster 
described above. Pans about 3” in diameter and %%" deep 
are employed. After ;priming, four days are allowed for 
drying. Upon the surface of each is placed 2 cc. of water 


FIGURE 172 
SUPER-ACCELERATED ALKALI-WATER TESTS 


View of basement laboratory floor with 8 long pans filled with 255 painted 

panels semi-submerged in water. Dark spots on some panels indicate water 

that has come through panel affecting the oil and bringing the saponified 
yellow product to the surface. 


and a watch glass placed over the water to prevent evapora- 
tion. If the water is absorbed, an additional quantity is 
added. After a period of three hours, the excess moisture is 
wiped off and the panels re-weighed. The increase in weight 
is the water absorbed, which is then calculated in per cent, 


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Exposure Tests 


. . 
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392 


393 


Exposure Tests 


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ratory are indicated 


ight of the plaster panels 


based upon the we 


labo 


The writer has also conducted tests w 


referred to on page 


ined in this 


. 


obta 


below, some results 


anels such as are 


th p 


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389, 


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394 Exposure Tests 


ished with white lacquer coat- 


Plaster panels primed with No. 11 or No. 13 Primer and fin 


the panels, they are immediately placed in a large cabinet, 
cooled to a temperature of 40° F. by an ice making equip- 
ment, or placed in a chamber saturated with water vapor and 
heated to the desired degree. 


Testing the Durability of Airplane Doping Systems.—One 
of the requisites for a doping system is lowness in weight. 
Since standard cotton airplane cloth weighs about 4% oz. per 
sq. yd., it is desirable that the total doping system should not 


wv 
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Exposure Tests 395 


— Ela, 


% Water 


No. Primer Absorbed 
ee Ste cis cain oes vinlel ore Ge vie oe e's oa towels eens ae 54.0 
SINCE ES 2 Bap 
8 Magnesium Fluosilicate H-T Solution ..........-e-e eevee, 45.0 
Peeters TOU woaiuim Silicate (20° Be.) 200 .....ccecccesesves 21 
5 Cold Water Paint—Glue Base Type .............ceevcceeves 54.6 
Peeiiesdipnate (2 1bs, per gal. of water) ........ceenesceeons 48.9 
7 Tung Oil White Flat Wall Paint, not thinned..........%... 0.1 
8 Tung Oil White Flat Wall Paint plus 1 pint Raw Tung Oil per 

eM aieic ly cae elas ee a he ee bs ers eee ew ee a 

9 Tung Oil—Ester Gum Spar Varnish 100, Mineral Spirits 25.. 0.0 

Mumm Mineral Spirits GO . 0... cece ce emer eect ena neees 16.3 

MIM VATUICN LAQUIC .. 1. se eee ct eee re eee tweet esac wenns 0.1 

12 Lead Linoleate 15, Zinc Linoleate 15, Toluol 70 ........... pie 

Pee erminiiny ptearace 15, Turpentine 70 .........02.0ececceee Oct 

EE Oy ee gab rev ols sie ease ows won ore eae 1338 

Benen SOlltion OU, Rosin 50 20... cece eves e ee sere sewcenees 0.0 


16 32 oz. Cotton Solution 100, Ester Gum 50, Toluol 70, Lindol 10 = 1.0 


add more than 3% oz. per sq. yd., making a total of approxi- 
mately 8 oz. The addition of an ounce per sq. yd. to a fabric, 
through the protective coating system, may add tremendously 
to the weight carried by a plane, due to the very large yardage 
used. Lower speed and greater fuel consumption might re- 
sult from such added weight. Another requisite is tautening 
power. Tautening is probably developed by the shrinkage of 
the cellulose compound as it emerges from solution in the 
solvent. The type, character, and amount of solvent used in 
dopes has a very pronounced influence upon the degree of 
tautness developed. The grade of cellulose compound used 
is also of importance. For instance, in nitrate dopes the type 
usually applied is ‘‘dope’’ cotton, and the degree of nitration 
is such that the viscosity is very high; a solution containing 
as much as eight ounces of nitrocellulose per gallon being 
quite viscous. The tensile strength of the doped fabric is 
also a matter of great importance; the application of the dope 
usually increasing the tensile strength to a very marked ex- 
tent. If, however, the dope breaks up during exposure to 
sunlight and develops free acid compounds,, the cloth is 

attacked, and very rapid lowering of strength is observed. It 
should be borne in mind, however, that the usual period dur- 
ing which a plane is flown is 200 hours. After that period it 
is customary to rip all the fabric off the wings to examine the 
structural parts for any signs of weakening. For this reason, 
doping systems that will last 200 flying hours with satistac- 
tory results under conditions of high humidity, temperature 

and sunlight, are usually considered satisfactory. 


396 Exposure Tests 


FIGURE 176 


Underside of doped fabric first coated with a gelatine tautener. 
After exposure very rapid fungus growth was observed. 


For testing the comparative effectiveness of airplane dopes, 
the writer uses fifteen inch square frames made of one inch 
dressed white pine joined together at the corners. To these 


Exposure Tests 397 


open frames are attached, under fairly definite tension, stand- 
ard cotton airplane cloth such as is used by the Navy Depart- 
ment on all seaplanes. After the fabric is tacked in place, 
the dope is applied aecording to the desired schedule. Panels 
are then placed upon a test rack at an angle of 45 degrees to 
the vertical, facing south, and, if possible, sprayed daily with 
water for a period of one hour. Very rapid results are ob- 
tained. In a period of three months much information can 
be secured regarding the serviceability of various doping 
schemes. At the end of that period of time, the frames are 
removed to the laboratory and tested for tautness with the 
finger, or with an apparatus which records tautness in numeri- 
eal values. Strips of fabric can them be removed from the 
frame and tested for tensile strength and elongation in order 
to determine whether any loss has taken place due to the 
deterioriation of the dopes or due to the effects of ultraviolet 
light which may have penetrated through the dope films. 
There are given below the results on a few out of several 
hundred tests which have been conducted by the writer at the 
Pensacola Naval Air Station and other points. 


2 


398 Exposure Tests 


FIGURE 177 


Both applied on airplane fabric previously doped with 4 coats of clear nitrate 
dope. After weathering 4 months the surfaces were subjected to thumb pres- 
sure. Note concentric ring cracks on surfaces where clear varnish was used, 
allowing embrittling effect of sunlight. Surface on left protected with pig- 
mented spar varnish is still distensible and shows no effects of pressure. 
Pigmentation shuts out active rays of sunlight. 


CLEAR SPAR VARNISH 


PIGMENTED SPAR VARNISH 


aioe 


399 


Exposure Tests 


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CHAPTER XXIII 


ANALYSIS OF PAINT OILS 


Some of the material relating to this subject, which ap- 
peared in previous editions of this volume, was used as the 
basis of methods adopted in specifications of the A. 8. 'T. M. 
which appear below. The specification for linseed oil is first 
presented. Additional matter in connection with the deter- 
mination of foots, unsaponifiable matter, and the hexabromide 
number of oil, is then included. Oils other than linseed oil 
in general may be analyzed by following these methods. Data 
is also presented in Table 51 relating to the constants of many 
oils examined at this laboratory. Following the matter on 
linseed oil there is presented the A. 8. T. M. specifications for 
-raw tung oil, for perilla oil, and for soya bean oil, with some 
additional notes relating to tests which are not included in 
the specifications. 


TABLE 51.-—Constants of Oils Examined in Writer’s Laboratory. 


i o 7 A 
= ; q i = 
S 
Oil. Species. & 5 | 8 re ee 
Se Be Be Boe 
SOO] 28 | Ge) 2) Be 
Sighe| sa | 82] 3 | 8a 
Peis. sites < | 
ie een Salvia. cuk«-. 934 | 196.3| 192.2) .6 | 1.4885 | ~ 
Hispanica > 
ee re 8 ae 921 | 125. | 190.1] 4.1 | 1.4800| & 
Mays S 
Cottonseed....... Gossipium...... .924 | 111.7) 194.3) .9 | 1.4720 es! 
Herbaceum & 
Hempseed....... Cannabis....... .927 | 149.4) 191.1) 3.9 | 1.4822 = 
Sativa ee 
Paoomceed......| Eriodendron....| .924 | 119. | 196. |.....}........ a 
Anfractuosum > 
Linseed (Boiled)..| Linum......... GATE TIO TR 7all aeio) | 48907) oe 
. Usitatissimum ~) 
Linseed (Heavy | Linum......... .968 | 183. | 189. | 2.8 | 1.4966 TA 
Bodied Usitatissimum 2 
Linseed (Lithogra-| Linum......... .970 | 102. | 199. | 2.7 | 1.4978 s 
graphic). Usitatissimum 
Linseed (Raw)...| Linum......... 934 | 186. | 191. | 2.0 | 1.4800} & 
Usitatissimum CF 
RCIA i wc let oxen Conepia.....<.-- SOGU nial OO co Aly et il, eaneta ce a 
Grandifolia 


Palo Maria...... Calophvllum....| .934 | 96.5! 193. [46.1 | 1.4743 


402 


Analysis of Paint Oils 


TasLeE 51—Cont.—-Constants of Oils Eramined in Writer's Laboratory. 


& 
= 
Fi 
Oil. Species. = 
goo 
paid 1D LAD 
Thy 
Inophyllum 
Porline-35.o 568 Perla cis eres 934 
Ocimoides 
Poppyseed....... Papaver:2 ou: a ah Gee 
Somniterrum 
Raisinseed (Grape-|s a en ee .926 
seed). 
THOSINUO: 6 oe Pinne i feo .964 
Palustris 
Rubberseed...... Hevea ss 33a .924 
Brasiliensis 
Sésame ss 5.0 ; Sesamum....... .924 
Orientale & In- 
dicum 
Soya Bean....... Sols ce eee 924 
Hispida 
Sunflower...... Helianthus. .... 924 
Annus 
Lumbane 72-3, Aleurites....... 927 
(Candlenut). Moluccana 
Lumbang (Soft). .| Aleurites....... .938 
Trisperma 
Peanitice cae Arathia.\i25,.) eee 
Hypogaea 
Tung (American) .| Aleurites....... .941 
Fordii 
Tung (Chinese)...} Aleurites....... .944 
Fordii 
Walnkt sie fey Juglans te .926 
Regia 
Wood (Japanese) .| Aleurites....... 934 
Cordata 
Channel Catfish.) 32 eee .923 
Fura roe ed Go Phota. ees 925 
Vitulina Ete. 
Grayfigh, 05 12) ee aoe ee .916 
Menhaden....... Alosa Menhaden | .932 
(Brevoortia Tyr- 
ranis) 
Salmon: oie a DANG OC eno 927 
Salar 
Sardine.:.:. 2s... )sOlipean us ee .919 
Sardinus 
Shark. . 4 sk ee ee .910 
Shark Liver...... Boréalig.3 5, oe .922 
Scymnus 
Skate Liver...... Squatina....... . 932 
Vulvaris 
Diana Bish 25% 2} are ee ae 933 
Whale vere G. Baloena..... 924 
Yellow Tailfish...| Seriola......... .932 


Dorsalis 


Iodine Number 


(Hanus) 


129. 


102.2 
166.0 
165.0 


164.2) 194.0) 4.4 


fe 
BS | 5 

ms 5 
=a ee 

a2 | 2 

ia] oO 

nn <x 

188. | 2.0 
1923-150 eee 
193. | 4.5 
35.5 |32.4 
193.2 Jo730 
190. | 1.4 
189. 32:3 


193.0) 2.2 
192-615 s.2 
192.0} 4.8 


183.0} 9.8 
177 .3)10.4 


158.9} 5.2 
62.2) 1.3 


179.9) 1.8 


a TAV LADAA) 


(STIO CHAS ANV 


——— 


| 


(STIO LAN) 


(‘STIO IVWINV ANIYVN) 


Analysis of Paint Oils 403 
es  " 


A. 8S. T. M. TENTATIVE SPECIFICATIONS FOR RAW 
LINSEED OIL 


I. PROPERTIES AND TESTS 


1. Linseed oil shall be the pure oil pressed from flaxseed and shall con- 


form to the following requirements: 
Maximum Minimum 


Specific Gravity 15.5° /15.5° C..... eee eee eee ees 0.935 0.931 
MSIL cbc c cc co tee ce ences eee ce we 4.0 Paar 
Saponification Number............cesseeeceeces 195.0 189.0 
Unsaponifiable Matter, per cent................- 1.50 Lectees 
MUN TEE CVV IIS) % 0. occ ee ce ce ee ae 180.0 

Loss on Heating at 105-110° C., per cent......... 0.2 

0 SE re Not darker than a freshly prepared solution of 


1.0 g. potassium bichromate in 100 cc. pure 
concentrated sulfuric acid (sp. gr. 1.84). 
Foots, per cent: 
IRE eas c)e ss aly els sees se ee ewe ees 1.0 
IPRUIMN Rece cows kee ko e's, 6 s'en0 a's vie tee nesses 4.0 


II. METHODS OF TESTING 


2 The oil should be tested in accordance with the following methods: 

General.—All tests shall be made on oil which has been thoroughly agi- 
tated before the removal of a portion for analysis. 

Specific Gravity—Use a pyknometer, accurately standardized and having 
a capacity of at least 25 ce., or any other equally accurate method, making 
the test at 15.5° C. water being 1.000 at 15.5° C? 

Acid Number—Weigh from 5 to 10 g. of the oil. Transfer to a 3800-ce. 
Erlenmeyer flask. Add 50 cc. of a mixture of equal parts by volume of 95- 
per-cent ethyl alcohol and c.p. reagent benzol. (This mixture should be 
previously titrated to a very faint pink with dilute alkali solution, using 
phenolphthalein as an indicator.) Add phenolphthalein indicator and titrate 
at once to a faint permanent pink color with 0.2 N sodium hydroxide solution. 
Caleulate the acid number (milligrams KOH per gram of oil). 

Saponification Number.—Weigh about.2 g. of the oil in a 300-cc. Erlenmeyer 
flask. Add 25 ce. of alcoholic sodium hydroxide or potassium hydroxide solu- 
tion. Put a condenser loop inside the neck of the flask and heat on the steam 
bath for one hour. Cool, add phenolphthalein as indicator, and titrate with 
0.5 N H,SO,4. Run two blanks with the alcoholic sodium hydroxide solution 
These should check within 0.1 cc. 0.5 N H,SO4. From the difference between 
the number of cubic centimeters of 0.5 N H,SO,4 required for the blank and 
for the determination, calculate the saponification number (milligrams KOH 
required for 1 g. of the oil). 

Unsaponifiable Matter—Weigh 8 to 10 g. of the oil. Transfer to a 250-cc. 
long-neck flask. Add 5 cc. of a strong solution of sodium hydroxide (equal 
weights of NaOH and H,O) and 50 ce. of 95-per-cent ethyl alcohol. Put a con- 
denser loop inside the neck of the flask and boil for two hours. Occasionally 
agitate the flask to break up the liquid, but do not project the liquid onto 


*Tf linseed oil of the high-iodine-number type is desired, the minimum 
iodine number, as specified above, should be changed to 188.0. 


404 Analysis of Paint Oils ) 

an nnnnnn enn ncn ncn nner nn nr reer renee SSS 
the sides of the flask. At the end of two hours, remove the condenser and 
allow the liquid to boil down to about 25 ec. 

Transfer to a 500-cc. glass-stoppered separatory funnel, rinsing with water. 
Dilute with water to 250 ce, add 100 cc. of redistilled ether. Stopper and 
shake for one minute. Let stand until the two layers separate sharp and 
clear. Draw all but one or two drops of the aqueous layer into a second 500- 
ce. separatory funnel and repeat the process using 60 cc. of ether. After thor- 
ough separation, draw off the aqueous solution into a 400-cc. beaker, then the 
ether solution into the first separatory funnel, rinsing down with a little 
water. Return the aqueous solution to the second separatory funnel and 
shake out again with 60 cc. of ether in a similar manner, finally drawing the 
aqueous solution into the beaker and rinsing the ether into the first separatory 
funnel. 

Shake the combined ether solution with the combined water rinsings and 
let the layers separate sharp and clear. Draw off the water and add it to the 
main aqueous solution. Shake the ether solution with two portions of water 
(about 25 ec. each). Add these to the main water solution. 

Swirl the separatory funnel so as to bring the last drops of water down to 
the stopcock and draw off until the ether solution just fills the bore of the 
stopcock. Wipe out the stem of the separatory funnel with a bit of cotton on 
a wire. Draw the ether solution (portionwise if necessary) into a 250-ce. 
flask and distill off. While still hot drain the flask into a small weighed 
beaker, rinsing with a little ether. Evaporate this ether, cool the beaker and 
weigh. (The unsaponifiable oil from adulterated drying oils may be volatile 
and aS a consequence may evaporate on long heating. Therefore, heat the 
beaker on a warm plate, occasionally blowing out with a current of dry air. 
Discontinue heating as soon as the odor of ether is gone. ) 

Iodine Number.—Place a small quantity of the sample in a small weighing 
burette or beaker. Weigh accurately. Transfer by dropping from 0.09 to 0.15 
g. of oil to a 500-ce. bottle, having a well-ground glass stopper, or an Erlen- 
meyer flask, having a specially flanged neck for the iodine tests. Reweigh 
the burette or beaker and determine the amount of sample used. Add 10 ce. 
of chloroform. Whirl the bottle to dissolve the sample. Add 10 cc. of 
chloroform to each of two empty bottles like that used for the sample. Add 
to each bottle 25 cc. of the Wijs solution and let stand with occasional shaking 
for 1 hour in a dark place at a temperature of from 21 to 23° GC. Add 10 ce. of 
the 15-per-cent potassium iodide solution and 100 ee. of water. Titrate with 0.1 
N sodium thiosulfate, using starch as an indicator. The titrations on the two 
blank tests should agree within 0.1 cc. From the difference between the aver- 
age of the blank titrations and the titration on the samples and the iodine 
value of the thiosulfate solution calculate the iodine number of the samples 
tested. (Iodine number is given in centigrams of iodine to 1 g. of sample.) 

Preparation of Wijs Iodine Monochloride Scolution.—Dissolve iodine in 
glacial acetic acid that has a melting point of 14.7 to 15° C. and is free from 
reducing impurities in the proportion so that 12 g. of iodine will be present in 
1000 cc. of solution. The preparation of the iodine monochloride solution 
presents no great difficulty, but it shall be done with care and accuracy in order 
to obtain satisfactory results. There shall be in the solution no sensible excess 
either of iodine or more particularly of chlorine over that required to form the 
monochloride. This condition is most satisfactorily attained by dissolving in 


Analysis of Paint Oils 405. 
eset 
the whole of the acetic acid to be used the requisite quantity of iodine, using a 
gentle heat to assist the solution, if it is found necessary. Set aside a small 
portion of this solution while pure, and pass dry chlorine into the remainder 
until the halogen content of the solution is doubled. Ordinarily it will be 
found that by passing the chlorine into the main part of the solution until 
the characteristic color of free iodine has just been discharged, there will be a 
slight excess of chlorine, which is corrected by the addition of the requisite 
amount of the unchlorinated portion until all free chlorine has been destroyed. 
A slight excess of iodine does little or no harm, but excess of chlorine must 
be avoided. 

Loss on Heating at 105 to 110° C_—Place 10 g. of the oil in an accurately 
weighed 50-ce. Erlenmeyer flask and weigh. Heat in an oven at a tempera- 
ture between 105 and 110° C. for 30 minutes, then cool and weigh. Calculate 
the percentage loss. This determination shall be made in a current of carbon 
dioxide gas. 

Color.—Prepare a fresh solution of 1 g. pure potassium bichromate in 100 
cc. of pure concentrated colorless sulfuric acid (sp. gr. 1.84). Place the oil 
and colored concentrated solution in separate thin-walled clear-glass tubes 
of the same diameter (1 to 2 cm.) to a depth of not less than 25 cm., and 
compare the depths of color by looking transversely through the columns of 
liquid by transmitted light. . : 

Determination of Percentage Foots—Method.—With all materials at a 
temperature between 20 and 27° C., mix, by shaking for exactly one minute 
in a graduated tube, 25 cc. of the well-shaken sample of oil, 25 cc. of acetone 
and 10 ce. of the acid calcium chloride solution. The tube shall then be 
clamped in an upright position where settling can take place for 24 hours. 
The temperature during this period should be between 20 and 27° Gs 

The volume of the stratum lying between the clear calcium chloride solu- 
tion and the clear acetone and oil mixture is read in 0.1 ce. or a fraction there- 
of. This reading multiplied by four expresses the amount of foots present 
as a percentage by volume. es 

The tube referred to may be a burette or a color comparison tube. It 
should have an internal diameter of 1.0 to 1.5 em., and a capacity of not less 
than 70 ce. The graduations in 0.1 ce. should extend at least from 10 ee. to 50 
ce. above the bottom of the tube. The acid calcium chloride solution is pre- 
pared by saturating with calcium chloride a mixture of 90 parts water and 
10 parts concentrated hydrochloric acid (sp. gr. 1.19). 

Heated Oil Test.—Heat a portion of the oil to 65° Ce Noldzit- within 2° C. 
of that temperature for 10 minutes; then cool it to room temperature (20 to 
27° C.). Subject the sample promptly to the foots tests as described above. 

Chilled Oil Test.—Heat a portion to 65° Gy. uold St within.-2° C. of that 
temperature for 10 minutes; then place it in a dry, clean bottle, stopper tightly, 
and place in a cracked ice and water mixture (0° C.) for exactly 2 hours. At 
the end of this time, place the bottle for exactly 30 minutes in a water bath at 
25° C., then subject promptly to the foots test, 


Foots in Linseed Oil (Discussion).—Sub-Committee V on 
Linseed Oil, of the American Society for Testing Materials, 
during recent years has conducted a vast amount of work of a 


406 Analysis of Paint Oils 
os 
cooperative nature, especially in relation to the determination 
of ‘‘foots’’ in linseed oil. Apparently the foots content of 
oil consists of three elements, namely, (1) moisture, (2) high 
melting point saturated fats which solidify at or below normal 
temperature, and (3) mucilaginous material which is held in 
the oil largely in suspension and in collodial solution. The 
albuminous material referred to appears to be identical with 
the substances forming the ‘‘break’’ when linseed oil is heated. 
It has been found difficult to determine the percentage of 
high melting point fats, since temperature and moisture con- 
ditions affect to a very large degree the amount of these fats 
which are detected by the various methods which have been 
proposed. Among the methods proposed in the committee 
work and reported on in 1924 are the following: 

1. ‘‘Foots’”’ Test on thoroughly agitated sample as received 
to be made by tentative A. S. T. M. method as described in 
Specifications D 51 - 18 T. 

2. ‘Boots’? Test on a portion, removed after thorough agi- 
tation, heated to 150° F. (65.5° C.) for 10 minutes and allowed 
to cool to room temperature (70 to 87° F.). 


3. ‘‘Foots’’ Test on a portion, removed after thorough agi- 
tation, chilled at 32° F. (0.0° C.) for 5 hours and allowed to 
come to room temperature (70 to 80° F.). 


4. ‘‘Foots’’ Test on a portion, chilled as in (3), heated at 
150° F. (65.5° C.) for 10 minutes and allowed to cool to room 
temperature. 

The results given by some of these methods are presented 
in Table 52. 


TABLE 52 
Foots, per cent Iodine Number 
Chilled 
Laboratory Foots,as Heated Chilled and Hanus Wijs 
Received to150°F. to32°F. Heated 
O1L No. 56 

Nos. 1s) Bonneys a see eee 1.4 1.4 2.4 1.4 178.4 183.5 

Nose.) Hull ce aie eeee 12 0.6 1.4 0.4 175.8 183.4 
No. 3. (Bailey ent eer ee ye 6. 1.0 4.6 p Oar yf 183.62 

Nowde Booves 25. eee 2.56 1.96 1.6 ue types! 182.5 

Nowd. - Thompsons... wane 1.10 0.5 5 lr 1.0 177.8 182.7 

NOs Gate aSlerccst asset ete aan 0.7 0.7 1.8 2.4 177.3 182.1 

NO. Te SA Davibs os. 5 eee 1.0 0.4 1.2 0.8 178.5 181.3 
NO@..8. > sStecleeaiceire comer ne 1.4 0.8 1.4 1.0 179.3 181.5 
INO; 92) Croliwee. | ke ome crema 2.0 2.0 2.0 2.0 STARS See a aes 
IN VOT AGE ite isos cncoeunensvees 1.48 1.67 1.6 1.6 176.64 182.57 
Pita hie. ee eon ck eee 2.56 6. 2.4 4.6 179.3 183.62 

Li Wicca Bee ee eee 0.7 0.4 ut 0.4 171.1 181.3 
Difference: 23ers eee 1.86 5.6 1.4 4.2 8.2 2.32 
Difference between High and 
AANGTAROS ai che basco ee 1.08 4.43 0.8 3. 2.66 1.05 
Difference between Low and 

AV GVOIO Fa rhs ssa Ces ee 0.78 ale Le 0.6 1.2 5.54 1.27 


Analysis of Paint Oils 407 


The method proposed by the committee for the determina- 
tion of breaks or mucilaginous material in the oil was as fol- 
lows: 


Break Test—Twenty-five grams of the well-mixed oil are 
weighed (accurately to 0.1 g.) into a 50-cc. Pyrex glass beaker. 
Three drops of ¢. p. hydrochloric acid (sp. gr. 1.19) are added 
and stirred thoroughly into the oil. The beaker is then placed 
on a wire gauze, supported by a tripod, and heated with the 
free flame of a Bunsen or Tirrill burner in such a way that the 
rate of temperature increase will be from 125 to 150° F. (70 
to 85° C.) per minute. A thermometer, suspended so that its 
bulb is approximately in the center of the liquid, should be 
used to register the temperature during the heating. If the 
oil contains break, the evolution of bubbles attendant upon the 
removal of the air and moisture usually ceases at the moment 
of the formation of the break, which will rapidly cover the 
bottom of the beaker with a gelatinous mass honeycombed 
with bubbles of air. When the break formation has completely 
covered the bottom of the beaker, it should be gently dis- 
lodged with the thermometer or a glass rod but under no cir- 
cumstances should the oil be agitated in any way prior to the 
break. When the temperature has reached 550° F. (288° C.) 
heating is discontinued and the oil allowed to cool to room 
temperature. The cooled oil and break are now transferred 
to a 250-cc. Erlenmeyer flask and the beaker thoroughly washed 
with five successive portions (of 25 ec. each) of ¢ p. carbon 
tetrachloride. These washings are added to the flask contain- 
ing the oil and break. <A small glass rod should be used to 
loosen any particles of break adhering to the sides or bottom 
of the beaker. The flask is now tightly stoppered and thor- 
oughly shaken for two minutes in order to completely extract 
any oil which may have been included in the break. The di- 
luted oil and break are then filtered on a Buchner funnel 
through filter paper previously dried to constant weight at 
220° F. (105° C.) and weighed accurately to 0.001 g. (What- 
man filter paper No. 4 will be found capable of giving satis- 
factory results for this purpose, although any similar paper 
capable of giving rapid and perfect filtration of gelatinous 
precipitates will also suffice.) Suction should be used in all 
cases to facilitate filtration. The break retained on the paper 
is washed with 50 ec. of carbon tetrachloride, which has pre- 
viously been used to wash out the Erlenmeyer flask, and with 
three 25-ce. portions of pure solvent. Each portion should be 
allowed to run almost completely through the paper before 
the addition of the next. The paper and break are finally 


408 Analysis of Paint Oils 
haan NT ENE 


dried for 30 minutes at 220° F. (105° C.), placed in a glass 
weighing bottle which is tightly stoppered, allowed to attain 
room temperature and weighed accurately to 0.001 g. The 
increase in weight of the filter paper multiplied by 4 gives the 
percentage of break (by weight) directly. 

During the year 1926, further work was conducted. The 
methods outlined for this work are presented below. 


1. Foots test according to method described in the A. 8. T. 
M. Tentative Specification for Foots Permissible in Properly 
Clarified Linseed Oil (D 51 - 18 T). 

2. Heat a portion of the oil to 65° C., hold it at that tem- 
perature for 10 minutes, allow to cool to room temperature 
and subject it to the foots test by the above method. | 

3. Ash Test—Ignite and weigh to an accuracy of 0.001 g., 
a porcelain crucible or small evaporating dish, having a capa- 
city of about 50 ec. Into this container, weigh about 25 g. 
of linseed oil. Add 3 drops of concentrated sulfuric acid. 
Heat the oil over a gas burner carefully to the fire point, ignite 
the oil, remove the burner and allow the oil to burn quietly 
as long as possible. Proceed carefully in this way, avoid- 
ing foaming and renewing heat only when the oil ceases to 
burn. When all foaming has ceased, apply the full flame of 
the burner until all the carbon has been burned and the ash is 
uncontaminated by black particles. Cool the dish in a desic- 
eator, weigh to an accuracy of 0.001 g., calculate the increase 
in weight as percentage of ash present in the oil. 

Some of the results obtained by the committee are presented 
below: 


TABLE 53 
“‘Foots’ and Ash Determinations Made on Three Samples of Linseed Oil 
Foots Test, Oil Heated Foots Test, Oil at Room ee 
to 65° C. Temperature Ash Determinations 
Observer 

Sample Sample Sample Sample Sample Sample Sample Sample Sample 

No. 60 No. 61 No. 62 No. 60 No. 61 No. 62 No. 60 No. 61 No. 62 
INOS Lee ee ee 0.4 0.8 2.8 0.6 1.8 5a 0.093 0.085 0.160 
Nop escheat ene 0.2 0.8 BIL. 0.8 2.0 ALO ine 0.100 0.140 
No. 38.... 0.8 1.0 3.2 1.0 1,2 4.8 0.083 0.095 9.158 
NOSE Sas hese oie 0.33 0.93 4.0 0.8 1.4 5.2 0.089 0.107 0.129 
NG5. ee ee 4 0.6 3.2 1 1.4 6.4 0.093 0.004 0.135 
NGs6a3 oo es 0.0 0.8 2.4 al74 2.0 6.4 0.119 (0.144) 0.131 
INGitiiee eee 0.3 1.0 3.6 0.4 1.2 3.6 0.082 0.068 0.086 
INOS Sohne eee 0.4 0.4 (9.2) 1.6 1.8 9.2 0.110 0.114 0.149 
ING 3052 ieee eee Le 2 4.3 1.6 2.4 5.6 0.091 0.102 0.109 
INO, JOR eee 0.0 (0.0) (0.0) 1.6 1.6 6.0 0.120 0.100 0.120 
A Verages cor s4) cic 0.40 0.83 3.34 pi tea 5.6 0.097 0.096 0.132 
Maximumn................ 1 Bis 1.2 4.3 1.6 2.4 9.2 0.120 0.114 0.160 
Minimum................ 0.0 0.4 Ae 0.4 1.2 3.6 0.082 0.068 0.086 
Deviation above 

mean, per cent 200 44 29 A5 Al 64 24 19 21 

Deviation below 
mean, per cent.... 100 52 28 64 29 36 15 29 35 


Analysis of Paint Oils 409 


After giving careful consideration to the work that was con- 
ducted, the sub-committee was of the opinion that the most 
satisfactory criterion for foots is the determination upon oil 
that has been heated to 65° C., which gives a measure of the 
mucilaginous material in the oil, and secondly a determination 
upon oil which has been chilled to 0° C., which gives a meas- 
ure of the mucilaginous material plus foots which are easily 
solidifiable in the cold and which often separate from the oil 
during cold weather. The committee suggested that 1% and 
4% respectively of these constituents were proper maximum 
limits for foots as determined under these two conditions. 


Jameson-Baughman Foots Test.*—Weigh accurately 10 
grams of the sample in a 50 ce. flask and transfer with the aid 
of petroleum ether to a 500 cc. pear-shaped separatory funnel, 
using in all 50 ce. of low boiling petroleum ether (B. P. less 
than 80° C.). Have the stopeock of the separatory funnel 
lubricated with water. Agitate the oil and petroleum ether 
until a homogeneous solution is formed. Add 10 ec. of a 14 
per cent potassium hydroxide solution, insert the stopper, and 
shake vigorously for 3 minutes. Then add 25 ce. of 50 per 
eent aleohol and shake for 15 or 20 seeonds. Allow to stand 
until the mixture separates into 2 layers. If the alcohol-alkali 
solution is allowed to remain in contact with the petroleum 
ether solution too long there is danger of saponifying some of 
the neutral oil. A contact of one-half hour will-not cause a per- 
ceptible error and this time is more than ample to effect a good 
separation of the layers. Draw off the lower layer and the 
precipitate into a 200 ce. separatory funnel, and rinse the in- 
side of the outlet tube of the 500 ec. separatory funnel with a 
little petroleum ether. Add 20 ce. of petroleum ether to the 
contents of the 200 ee. separatory funnel, shake, and allow the 
layers to separate. Draw off the lower layer and the precipi- 
tate into a 250 ec. beaker. Rinse the outlet tube of the separa- 
tory funnel with petroleum ether into the beaker. Add the 
upper layer to the main petroleum ether solution in the large 
separatory funnel. Pour the alcohol-alkali solution back into 
the 200 ce. separatory funnel and extract with another 20 ce. 
portion of petroleum ether. Repeat this treatment a third 
time to insure the complete recovery of neutral oil. Save the 
alcohol alkali solution for the determination of the fatty acids. 
Wash the petroleum ether solution of the oil three times with 
15 ce. portions of 50 per cent alcohol and add the washings to 


* Presented originally in Scientific Section Circulars for 1927-28. 


410 Analysis of Paint Oils 
te 


the aleohol-alkali solution in the 250 ce. beaker. Transfer the 
solution of the oil to a weighed 300 cc. Erlenmeyer flask and 
rinse the separatory funnel with several small portions of 
petroleum ether. Distill off as much as possible of the solvent 
by placing the flask in a water bath. Heat the flask in an oven 
at 120° or 125°, using an atmosphere of carbon dioxide to pre- 
vent oxidation of the oil, until a constant weight is obtained. 
In most cases 2 hours’ heating is sufficient. Calculate the 
percentage of neutral oil. | 
Place the beaker containing the alcohol-alkali solution on 
the steam bath and evaporate the alcohol. Then add about 
75 ec. of water and, when the soap is dissolved, acidify the 
solution with hydrochloric acid. Cover the beaker and heat 
on the steam bath until the fatty acids have collected on top 


TABLE 54 


ANALYSIS OF RAW LINSEED OIL 
Acid Acidity Iodine 


Neutral Fatty value of as oleic number 
Sample oil acids Break oil acid (Hanus) 
% % % % 
A, 8.7. Ms No. G0? soca s 98.32 1.26 0.42 2.23 1.12 179.5 
: Mis RAE. Satan ore 98.35 1.22 0.43 Ee Pee ee ry 
ASE OM: ING GL swiss toe 98.49 1.23 0.28 2.23 1.12 184.8 
oh EN ates: oa ees eat 98.45 1.30 0.25 cies ae eee 
A. 8:70. MANO: O2F oo ee 97.92 1.43 0.65 2.28 1.14 190.5 . 

: Pe pen era or 97.93 1.45 0.62 teas 5 Gane Gears 


- we gt Mera otanals ae 97.95 1.38 0.67 dices tye ¥ as ay 

Ne: 1 (1924) wacom ees sexs 98.36 1,15 0.49 1.89 0.95 178.5 
oie etalon als orale eeiar Bae 98.38 1.19 0.43 a ape sae 
S82 ST a Veta eaeceei ie eae 98.39 1.20 0.41 


ING, ss25G Rect oe eee 98.77 0.98 0.25 1.67 0.84 188.9 
Been ee rs: ee cree ee a 98.69 0.98 0.33 a ot “Ae rey 
INO) <3 opine wis sincere ehniees, meee 98.54 1.19 0.27 2.17 1,09 181.3 
NO. “45%. a iis os ae ee eee oe eee 93,90" ae 0.26 1.26 63 186.3 
Se Wine. 6 A ieget dea atria ee ee 98.96 0.75 0.29 va $l ie ee Davai 
NO... Bois sh eee eee 98.18 1.38 0.44 2.35 1.18 184.0 
pager Eyer ear ee Pies fy 98.16 . 1e¢ 0.47 Bene eae Stele 


of the solution. Cool until the fatty acids become solid, filter, 
and wash with water until the fatty acids are free from chlor- 
ides. Place the funnel containing the filter paper with the 
fatty acids in the 250 ec. beaker and heat on the steam bath 
until beaker and filter are dry. Dissolve the fatty acids with 
small portions of petroleum ether. If the solution of the fatty 
acids is turbid, refilter it through the original filter. Collect 


*Figures given under “Break” include also the foots. Each sample was 
thoroughly mixed before analysis. These oils were kindly furnished by R. D. 
Bonney, Chairman of A. 8S. T. M. Sub-committee V on Linseed Oil. 

Oils 1, 2 and 3 were hot pressed and oils 4 and 5 were cold pressed. 

Oils 1 and 2 were expressed from Argentine seed while 3, 4 and 5 were 
obtained from American seed. 


Analysis of Paint Oils 411 


the filtrate and washings in a weighed 200 cc. Erlenmeyer 
flask. Remove the solvent as described for the determination 
of neutral oil, and weigh. Calculate the percentage of fatty 
acids. To obtain the per cent of break or break and foots, 
subtract the percentages of neutral oil and fatty acids from 
100. 


The results obtained are given in Table 54. 


Occasionally, after the withdrawal of the aleohol-alkali solu- 
tion, a small quantity of a finely-divided precipitate gradually 
separates from the petroleum ether solution of the neutral oil. 
During the washing with 50 per cent alcohol, this precipitate 
settles between the layers and it is usually safer not to with- 
draw it with the wash solution as there is danger of losing 
some neutral oil. In the few cases observed it has been found 
possible to decant the petroleum ether from this slight pre- 
cipitate. However, if necessary, the precipitate should be 
removed by filtration. Then the greatest care must be taken 
the all of the neutral oil from the filter with petroleum 
ether. 

From the results given, it will be observed that there is ap- 
parently no relation between the quantity of break in an oil 
and its iodine value. The one sample.with the highest iodine 
number also contains more of the break than any of the other 
samples given in the table. 


A.S. T. M. TENTATIVE SPECIFICATIONS FOR BOILED 
LINSEED OIL 


PROPERTIES AND TESTS 


1. Boiled linseed oil shall be pure linseed oil that has been treated by 
heating and incorporating compounds of lead, and at the option of the manu- 
facturer suitable compounds of other drying metals, so as to produce a 
product that will dry rapidly. It shall be clear, free from sediment, and 
shall conform to the following requirements, when tested in accordance with 
the methods described in Sections 2 to 12, inclusive: 

: Maximum. Minimum 


Pomerorearving on glass; HOurs..........0.se00 18.0 Bete 
Brecwmic Gravity, 15.5 /15.5° CC... 6 ec etse eee ens 0.945 0.951" 
EMMETT TNS 6 hata, 6p (5. oo ne nie ois Sis a 9.0 cle ae om soe ete 7.5 re 
mee OM ION INTIMIDED: «5s o.0 ic oie 0 9 6 «ord aye e eiele's 195.0 189.0 
Unsaponifiable Matter, per cent..............0-. 1.50 A 
Oiieemmmner ( WIjS). oc. ss cee eee siewceee eee eae 170.0 
Loss on Heating at 105 to 110° C., per cent...... 0.2 BLO Y 
RIUM RIT ge oo iokn a citi Gace Oka deldeve eae 0.50 ree 
REECE TNT 500 a cine casio: tsg omg Ala gitat a ace 6 ace whe aon Cede 0.05 


* When a high viscosity type of boiled linseed oil is required, the specific 
gravity shall not be less than 0.937. 


412 Analysis of Paint Oils 


METHODS OF TESTING 


2. General.—All tests shall be made on oil that has been thoroughly agi- 
tated before the removal of a sample for analysis. 

3. Time of Drying on Glass.—In determining the time of drying on glass, 
flow the sample over a perfectly clean glass plate. Place the plate in a 
vertical position in air that is at 30° C.+2°C. and of a humidity of 32-per- 
cent + 4 per cent saturation. After about two hours, test the film at intervals 
with the finger at points not less than 2.5 em. from the edges. The film 
shall be considered dry when it no longer adheres to the finger and does not 
rub up appreciably when the finger is lightly rubbed across the surface. 

4. Specific Gravity. In determining specific gravity, use a py knometer, 
accurately standardized and having a capacity of at least 25 ce., or any other 


equally accurate method, making the test at 15.5° C. water being 1.000 at 


15.326; 

5. Acid Number.—In determining acid number, weigh from 5 to 10 g. of the 
sample. Transfer to a 300-ce. Erlenmeyer flask. Add 50 ec. of a mixture of 
equal parts by volume of 95-per-cent ethyl alcohol and c.p. reagent benzol. 
(This mixture should be previously titrated to a very faint pink with dilute 
alkali solution, using phenolphathalein as an indicator.) Add phenolphthalein 
indicator and titrate at once to a faint permanent pink color with 0.2 N sodium 
hydroxide solution. Calculate the acid number (milligrams KOH required for 
1 g. of the oil). 

6. Saponification Number.—In determining saponification number, weigh 
about 2 g. of the sample in a 300-cc. Erlenmeyer flask. Add 25 cc. of alcoholic 
sodium hydroxide or potassium hydroxide solution. Put a condenser loop in- 
Side the neck of the flask and heat on the steam bath for one hour. Cool, add 
phenolphthalein as indicator, and titrate with 0.5 N H,SO,4. Run two blanks 
with the alcoholic sodium hydroxide solution. These should check within 
0.1 ce. of 0.5 N H,SO4. From the difference between the number of cubic 
centimeters of 0.5 N H2SO,4 required for the blank and for the determination, 
calculate the saponification number (milligrams KOH required for 1 g. of 
the oil). 

7. Unsaponifiable Matter.—In determining unsaponifiable matter, weigh 8 
to 10 g. of the sample. Transfer to a 250-ce. long-neck flask. Add 5 ee. of a 
strong solution of sodium hydroxide (equal weights of NaOH and H,O) and 
50 cc. of 95-per-cent ethyl alcohol. Put a condenser loop inside the neck of 
the flask and boil for two hours. Occasionally agitate the flask to break up 
the liquid, but do not project the liquid onto the sides of the flask. At the 
end of two hours, remove the condenser and allow the liquid to boil down 
to about 25 ce. 

Transfer to a 500-ce. glass-stoppered separatory funnel, rinsing with water. 
Dilute with water to 250 cc. add 100 ce. of redistilled ether. Stopper and 
Shake for one minute. Let stand until the two layers separate sharp and 
clear. Draw all but one or two drops of the aqueous layer. into a second 500-ce, 
separatory funnel and repeat the process using 60 cc. of ether. After thorough 
separation, draw off the aqueous solution into a 400-ce. beaker, then the ether 
solution into the first separatory funnel, rinsing down with a little water. 
Return the aqueous solution to the second separatory funnel and shake out 
again with 60 cc. of ether in a similar manner, finally drawing the aqueous 
solution into the beaker and rinsing the ether into the first separatory funnel. 


s 


Analysis of Paint Oils 413 


Shake the combined ether solution with the combined water rinsings and 
let the layers separate sharp and clear. Draw off the water and add it to the 
main aqueous solution. Shake the ether solution with two portions of water 
(about 25 ce. each). Add these to the main water solution. 

Swirl the separatory funnel so as to bring the last drops of water down to 
the stop-cock and draw off until the ether solution just fills the bore of the 
stop-cock. Wipe out the stem of the separatory funnel with a bit of cotton 
on a wire. Draw the ether solution (portion-wise if necessary) into a 250-ce. 
flask and distill off. While still hot drain the flask into a small weighed 
beaker, rinsing with a little ether. Evaporate this ether, cool the beaker and 
weigh. (The unsaponifiable oil from adulterated drying oils may be volatile 
and aS a consequence may evaporate on long heating. Therefore, heat the 
beaker on a warm plate, occasionally blowing out with a current of dry air. 
Discontinue heating as soon as the odor of ether is gone.) 

8. Iodine Number.—In determining iodine number, place a small quantity 
of the sample in a small weighing burette or beaker. Weigh accurately. 
Transfer by dropping from 0.09 to 0.15 g. of oil to a 500-ce. bottle, having a 
well-ground glass stopper, or an Erlenmeyer flask, having a specially flanged 
neck for the iodine tests. Reweigh the burette or beaker and determine the 
amount of sample used. Add 10 cc. of chloroform. Whirl the bottle to dis- 
Solve the sample. Add 10 cc. of chloroform to each of two empty bottles like 
that used for the sample. Add to each bottle 25 cc. of the Wijs solution and 
let stand with occasional shaking for 1 hour in a dark place at a temperature 
of from 21 to 23°C. Add 10 ce. of the 15-per-cent potassium iodide solution 
and 100 cc. of water. Titrate with 0.1 N sodiym thiosulfate, using starch 
aS an indicator. The titrations on the two blank tests should agree within 0.1 
ec. From the difference between the average of the blank titrations and the 
titration on the sample and the iodine value of the thiosulfate solution calcu- 
late the iodine number of the sample tested. (Iodine number is given in centi- 
grams of iodine to 1 g. of the oil.) 

Preparation of Wijs Iodine Monochloride Solution.—Dissolve iodine in 
glacial acetic acid that has a melting point of 14.7 to 15° C. and is free from 
reducing impurities in the proportion so that 13 g. of iodine will be present 
in 1000 ce. of solution. The preparation of the iodine monochloride solution 
presents no great difficulty, but it shall be done with care and accuracy in 
order to obtain satisfactory results. There shall be in the solution no sensible 
excess either of iodine or more particularly of chlorine over that required to 
form the monochloride. This condition is most satisfactorily attained by 
dissolving. in the whole of the acetic acid to be used the requisite quantity 
of iodine, using a gentle heat to assist the solution, if it is found necessary. 
Set aside a small portion of this solution while pure, and pass dry chlorine 
into the remainder until the halogen content of the solution is doubled. Ordi- 
narily, it will be found that by passing the chlorine into the main part of the 
solution until the characteristic color of free iodine has just been discharged, 
there will be a slight excess of chlorine, which is corrected by the addition 
of the requisite amount of the unchlorinated portion until all free chlorine 
has been destroyed. <A slight excess of iodine does little or no harm, but 
excess of chlorine must be avoided. 

9. Loss on Heating at 105 to 110° C_—In determining the loss on heating, 
place 10 g. of the Sample in an accurately weighed 50-cc. Erlenmeyer flask 


414 Analysis of Paint Oils 
deanna eer eee eee errr errr eee 
and weigh. Heat in an oven at a temperature between 105 and 110° C. for 30 
minutes, then cool and weigh. Calculate the percentage loss. This determina- 
tion shall be made in a current of carbon dioxide gas. 

10. Ash.—In determining ash, weigh a porcelain crucible or dish. Add 
from 10 to 25 ce. of the sample, carefully weighing the amount added. Place 
on a stone slab on the floor of a hood. Ignite by playing the flame of a burner 
on the surface of the oil and allow to burn quietly until most of the oil is 
burned off; then transfer to a muifle or over a flame and continue heating at a 
low temperature (not over a dull red) until all carbonaceous matter is con- 
sumed. Cool, weigh, and compute the percentage of ash. 

11. Leads.—In determining lead, dissolve the ash in dilute nitric acid to 
which a little hydrogen peroxide has been added and determine lead by the 
sulfate or any other equally accurate method. 

12. Appearance.—Transfer a portion of the sample to a clear glass tube 
and note appearance. 


There is presented below a method which has been used sat- 
isfactorily for purifying alcohol which is to be employed in the 
determination of unsaponifiable matter. A reference is also 
made to the Kerr-Sorber test for unsaponifiable matter, which 
has been used with satisfactory results by Dr. G. 8. Jamieson. 


Purifying Alcohol for Unsaponifiable—If necessary to 
purify the alcohol, proceed as follows. To each liter of alcohol 
add about a gram of silver nitrate dissolved in 2-3 ce. of water. 
Then add 3 g. of potassium hydroxide (for each liter of alco- 
hol) previously dissolved in about 20 ce. of alcohol, shake, and 
allow the mixture to stand for at least two days in a flask with 
a small beaker inverted over the neck. Either the clear al- 
eohol may be decanted or filtered from precipitate. | 


Kerr-Sorber Test for Unsaponifiable Matter.*—Accurately 
weigh about 5 grams of sample into a 200 ml. Erlenmeyer 
flask. Add 30 ml. of the aleohol and 3 ml. of the concentrated 
potassium hydroxide (1:1 aq.) solution. Place a small, short- 
stemmed funnel in the neck of the flask to serve as a conden-- 
ser. Boil gently on the steam bath for about 20 minutes or 
until complete saponification occurs. Cool to about 30° C., 
add 50 ml. of ether U. S. P., mix, and transfer to a 500 ml. 
separatory funnel. Rinse the flask with two successive 50 
ml. portions of ether, add to the separatory funnel, and mix 
thoroughly. Wash the saponification flask with 100 ml. of 
dilute potassium hydroxide solution (0.2 N) and pour into the 
separatory funnel in a slow, steady stream. Rotate the fun- 
nel very gently to secure better contact of the solutions but do 
not shake. (Shaking at this stage brings about stubborn 


* Kerr-Sorber Method modified by Hertwig, Jamieson, Baughman and 
Bailey. J. Assoc. Off. Agric. Chemists. Vol. VIII, p. 439-442 (1925). 


Analysis of Paint Oils 415 


emulsions.) Allow the liquids to separate completely and 
then slowly draw off as much of the soap solution as possible. 
Do not draw off any layer of emulsion that may be formed. 
Keep the volume of the ether at about 150 ml. by replacing 
that dissolved by the wash solutions. Further treat the ether 
solution with two successive 100 ml. portions of the alkaline 
wash solution in the manner described previously. Add 30 
ml. of water to the ether and rapidly rotate the liquid layers. 
When the layers have separated completely, draw off the 
water. Repeat this treatment until the washings are free 
from alkal, as shown by testing with phenolphthalein. Three 
washings usually suffice. Transfer the ether solution quanti- 
tatively through a pledget of cotton in the stem of a funnel 
to a weighed 250 ml. Erlenmeyer flask or beaker-flask. Before 
weighing the flask dry it in an oven at 100° C., and then allow 
it to stand in the air to constant weight. Distill off the ether 
on a hot plate, cool and weigh. The unsaponifiable matter 
from adulterated drying oils may be volatile mineral oil. 
Therefore, it is well to occasionally blow out the ether with 
dry air and discontinue heating when the odor of ether is 
gone. 


HExaBROMIDE Test FoR DETERMINING Purity oF LINSEED OIL 

The determination of the hexabromide value of linseed oil 
is probably the only method whereby adulteration with small 
amounts (5 per cent or greater) of soya bean or some similar 
oil ean be detected. This test shows the percentage of ether- 
insoluble bromides which can be formed from the mixed fatty 
acids of a given sample of linseed oil. 

It has been found that the Steele-Washburn method for 
hexabromides yields a fairly constant figure of 46 per cent for 
unadulterated commercial oils. 

Soya bean oil has been found to yield not over 6 per cent 
of hexabromides, while cottonseed oil shows a zero yield. 

The calculation given below will indicate how an addition of 
10 per cent soya bean oil to linseed oil will not lower the iodine 
value below the allowable minimum but will lower the hexa- 
bromide value to a marked degree: 

Assume a linseed oil with iodine number of 185 to be adul- 
terated with 10 per cent of soya bean oil, iodine value of 130. 


Then: .90 « 185 = 166.5 
LO < 180 ==" 13.0 


Iodine number of mixture = 179.5 


416 Analysis of Paint Oils 

a. 
Assume that the same linseed oil has a hexabromide yield of 
46 per cent while the soya bean oil yields 6 per cent of hexa- 


bromides. 
Then: .90 x 46— 414 
AO ae Ga 6 


Hexabromide yield of mixture=— 42.0 


A hexabromide yield of 42.0 per cent would be much lower 
than any normal linseed oil and would indicate adulteration, 
while an iodine number of 179.5 would not indicate adultera- 
tion. 2 


The two methods (Steele and Washburn or Bailey’s modi- 
fication thereof) by which the hexabromide test may be made, 
are given below. The Bailey modification differs from the 
Steele and Washburn method in that an acetic acid-bromide 
solution is used instead of a chloroform-bromide solution. The 
Bailey modification also entirely eliminates the use of chloro- 
form from the reaction mixture and does not require ‘‘amy- 
lene’’ or other reagent for removing the excess of bromide 
after the bromination of the fatty acids. The Bailey modifica- 
tion, however, requires the precipitated hexabromides to first 
stand over night in an ice chest instead of immediate washing. 


Steele erd Washburn Method.—The following reagents are 
necessary : 3 


1. Chloroform.—Shake ordinary U. 8. P. chloroform with 
several portions of water to wash out all the aleohol. Dry the 
product with granulated anhydrous calcium chloride over 
night in order to remove all traces of water. Decant from the 
calcium chloride and distil. Add to the distillate 3 ec. of abso- 
lute ethyl aleohol for every 100 ee. of chloroform. Keep in a 
stoppered brown bottle. 


2. Bromide Solution——Mix one part by volume of C. P. bro- 
mine* with two parts by volume of chloroform, prepared as 
above. This solution must be made up fresh each day because 
it deteriorates upon standing. 


3. Wash Ether—Shake ordinary ethyl ether with 10 per 
cent of its volume of ice cold distilled water. Separate and 
repeat the washing three times. Dry the washed ether with 
fused calcium chloride overnight. Decant the ether through a 


* The authors have observed that samples of bromine marked “C. P.” 
often contain considerable amounts of non-volatile material. All bromine 
which is used must be redistiled unless it is found that 5 gms. leave no 
weighable residue upon evaporation. 


Analysis of Paint Oils 417 


folded filter into another flask and add thin slices of sodium. 
Warm gently on a steam bath under a reflux condenser until 
the evolution of gas by action of the sodium has practically 
ceased and bits of freshly cut sodium remain bright in the 
ether. Distill the ether into a dry bottle and add an excess 
(at least three grams per liter) of finely powdered hexabrom- 
ide of the fatty acids of linseed oil previously prepared. If 
no hexabromide is on hand from previous determinations it 
may be easily prepared as follows: In a centrifuge tube dis- 
solve about 5 grams of the fatty acids of linseed oil in 15 to 20 
ec. of chloroform. Place the tube in a freezing mixture and 
add slowly, with shaking, bromine solution until a shght red 
color is permanent. Adda few drops of amylene to ile up 
excess of bromine. Whirl ina centrifuge until the precipitate 
has settled and then pour off the chloroform. Rub up the 
precipitate with 20 cc. of cold absolute ether, whirl in a cen- 
trifuge and pour off the wash ether. Repeat the washing 
with 3 more 20 ec. portions of ether. After drying, the hexa- 
bromide is pure enough for the preparation of wash ether. 
Shake at intervals for two or three hours or allow the mixture 
to stand over night. Then place the bottle in ice water so that 
the ether solution will be at zero or not above 2° C. for three 
hours. Decant the ether solution rapidly through a folded 
filter into a dry bottle and keep tightly corked in Ante to 
prevent loss of ether by evaporation. 


4. Amylene.—This material may be pur a ice ane 
Kastman Kodak Company. It is one of the organic chemicals 
prepared in the laboratory of the University roe LL rOveste cLt 
may be prepared in small quantities from amyl alcohol by the 
method of Adams, Jour. Am. Chem. Soc., 1918, page 1950. 


B. Preparation of the Fatty Acids. 


Weigh approximately 50 grams of linseed oil into a 11% liter 
Florence flask, and add 40 ce. NaOH solution (sp. gr. 1.4) and 
40 ee. of aleohol. Place the mixture on a steam bath and heat 
for about 14 hour. Add 1 liter of hot distilled water and in- 
sert into the neck of the flask a 2-hole rubber stopper carrying 
a tube which projects into the flask so that its end is slightly 
above the liquid, and pass a stream of COz2 through the tube 
into the flask. The soap mixture may then be heated, to re- 
move the alcohol, either over a free flame or on the steam bath. 
If the free flame i is used, a capillary ‘‘boiler’’? must be placed 
in the liquid, since otherwise the soap solution will bump badly. 
If excessive foaming takes place the current of CO» should be 
increased until it is strong enough to break da the foam. If 


418 Analysis of Paint Oils 


the solution is heated on the steam bath, usually about 2 or 3 
hours is required to remove the alcohol, while if it is boiled 
over a free flame, one-half hour is usually sufficient. After the 
alcohol has been removed, cool the soap solution and acidify 
with dilute HCI (1-1). Insert a 3-hole rubber stopper, carry- 
ing two glass tubes arranged as for a wash bottle, leaving the 
third hole in the stopper open for an outlet for the COs. The 
inlet tube should extend to just above the layer of fatty acids, 
and the outlet tube should extend to the bottom of the flask. It 
is essential that the outlet tube should not extend down more 
than an inch or two outside of the flask, as otherwise siphoning 
would take place, causing the liquid to boil inside the tube. 

Pass a stream of CO: through the system, and boil gently, 
using a capillary boiler to prevent bumping, until the layer of 
fatty acids is clear. Plug the hole in the stopper which acts as 
an outlet for the COz. The lower layer will be forced out 
through the outlet tube by the pressure of the CO,. In this 
manner remove as much water as possible without losing any 
of the fatty acids, then remove the stopper and add about 500 
ee. of hot distilled water, shake thoroughly so that the fatty 
acids are well washed, allow the fatty acids to separate and 
siphon off the wash water as before. Repeat the washing until 
the wash water does not give an acid reaction with methyl 
orange. Before removing the last washing, insert a capillary 
boiler and boil gently until the fatty acid layer is clear. After 
the last washing, remove the stopper and suck up with a pip- — 
ette the last few globules of water. Filter the hot fatty acids 
through a folded filter under an evacuated bell jar and keep in 
a well stoppered bottle. 


C. Preparation of Hexabromides. 

Weigh accurately in a weighed centrifuge tube (approxi- 
mately 614 inches long by 1 inch in diameter) 1.00 gram (plus 
or minus 0.05 gram) of linseed fatty acids, prepared as given 
above. Dissolve in 10 ce. of chloroform and place the tube in a 
freezing mixture kept as near—5° C. as possible, made by 
adding a little dilute hydrochloric acid to finely eracked ice. 
Add bromine solution from a burette at the rate of one or two 
drops per second, shaking the tube well during the addition. 
At first the bromine color will be rapidly discharged, but later 
the mixture will assume a permanent orange color indicating 
a slight excess of bromine. For most fatty acids of linseed 
oil about 1 cc. of the bromine solution will be found necessary 
to give the orange color. At this point run in rapidly 0.5 ce. 
more of the bromine solution, shake well, and allow the tube 
to stand in the ice mixture for ten minutes. Remove the tube 
from the freezing bath and add amylene drop by drop with 
shaking until the bromine color has entirely disappeared. 


Analysis of Paint Oils 419 
—$—<— eee 
Usually five to six drops of amylene are sufficient, but a slight 
excess does no harm. The addition of bromine solution must 
never be done in direct sunlight. 

Attach the tube to a good water vacuum pump (one which 
will indicate a pressure not greater than 40 mm. of mercury ) 
by means of a new one-hole rubber stopper. Eivaporate the 
chloroform in a vacuum, warming the tube in water at 50 to 
60° C. to hasten evaporation. The tube must be constantly 
shaken to prevent bumping of the chloroform. Towards the 
end of the evaporation, when the contents of the tube become 
more viscous, rotate and tilt the tube so that the oil will flow 
about half way up the sides and thus present more surface for 
evaporation. When practically all the chloroform has been 
evaporated, place the tube in a bath at 55 to 60° C. for fifteen 
minutes, keeping the suction on. | 

Detach from the pump and place the tube in a bath of finely 
eracked ice and water. When the tube is cold pour down its 
sides 20 ec. of cold wash ether, as prepared above. The wash 
ether should have been previously placed in four corked test 
tubes graduated at 20 ce. by a file mark and kept at 0° C. in an 
ice bath. Thoroughly stir and rub up the bromide mixture 
with a rod, breaking up all the lumps. “Return the tube to the 
ice bath for two minutes and then whirl in a centrifuge until 
the precipitate has settled into a hard cake and the super- 
natant liquid is clear. Return the tube to the ice bath for two 
minutes and then pour off the wash ether, making sure that no 
_ solid material is lost. Repeat the washing of the hexabromide 
precipitate three times in exactly the same way, using three 
20 ee. portions of ice-cold wash ether and rubbing up the pre- 
cipitate thoroughly each time. Use a weighed stirring rod and 
wash the precipitate adhering to the rod into the tube with 
the wash ether at each washing of the hexabromide. After- 
wards dry and weigh the rod plus the slight coating of precipi- 
tate and add the weight of material on the rod to the weight 
of the main portion of hexabromide. After the fourth ether 
washing has been poured off, carefully incline and tap the tube 
and spread the hexabromide precipitate part way up the sides. 
Warm the tube in water at 50 to 60° C. until most of the ether 
has evaporated. Attach to the suction pump and place the 
tube in a bath at 60 to 70° C. for fifteen minutes. Detach the 
tube from the pump, cool in cold water to room temperature, 
wipe dry with a towel and weigh at once. Dry the tube to con- 
stant weight in an oven at.100-110° C. The total weight of the 
precipitate times 100 divided by the weight of fatty acids 
taken, gives the hexabromide percentage. The hexabromide 
should dry pure white. 


420 Analysis of Paint Oils 


Special Precautions: 

1. Have the chloroform dry and adjust its alcohol content 
to 3 per cent. 

2. Make sure that all the chloroform is evaporated from the 
impure hexabromide before adding wash ether. This will be 
accomplished if the water pump indicates a pressure not 
ereater than 30-40 mm. and the tube is heated in the bath at 
60° C. for two-thirds of its lengths. 

3. Make sure that the wash ether is anhydrous and free from 
alcohol and that it is saturated with hexabromide at 0° GC. Un- 
less the wash ether is allowed to stand at 0° C. for a sufficient 
length of time before filtering off excess hexabromide, it will 
be super-saturated at 0° C. and will give high results. Care 
should be taken to prevent appreciable loss af ether by evap- 
oration; it is well to cool the stock bottle of wash ether on hot 
days before uncorking. 

4. Make sure that the centrifuge tube containing hexabro- 
mide and the wash ether are kept as near 0° C. as possible dur- 
ing the process of washing. The finely cracked ice should be 
replenished at intervals. 

5. It has been found that low and non-coneordant hexabro- 
mide results on pure linseed oil by the new method can nearly 
always be traced to the use of a faulty vacuum pump or to 
faulty rubber connections. Therefore, the operator should 
convince himself by test with a mercury manometer immedi- 
ately before making the determination that his pump, as used, 
will give a vacuum of not greater than 30 mm. mercury. Heavy 
walled pressure tubing should always be used for connections. 
A faulty pump or faulty rubber connections usually means 
that the chloroform is not all evaporated from the impure 
hexabromide and will exert a solvent action on the hexabro- ~ 
mide later on, thus giving low yields. 

6. If a Nelson rotary oil pump is available, it is an excellent 
plan to remove the last traces of chloroform by attaching the 
centrifuge tube to this type of pump for 15 minutes. The bulk 
of the solvent should be removed first by means of the water 
pump 

F. W ith either pump the tube should be heated in a bath of 
ae 65° C., during the evaporation of the last traces of chloro- 

orm. 


BatLtey’s MoptricaTION oF STEELE AND WASHBURN MerrHop FOR 
HEXABROMIDE NUMBER 
Principle: 
The unsaturated fatty acids when treated under proper con- 


_ Analysis of Paint Oils 421 


ditions with bromine absorb at each unsaturated linkage two or 
more atoms of bromine depending on the degree of unsatur a- 
tion. Thus at a double bond—C— —C—there is obtained a satu- 
rated bromo product : rothren 


| 
Br Br 
four bromine atoms are absorbed to give a saturated compound 
Bc. 3r 


co The solubility in ether of the bromo derivaties de- 
| | 
br. Br 

creases rapidly with increase of bromine content. Thus the di 
and tetra bromo compounds are easily soluble, whereas the 
hexa (and octo) compounds are only very sparingly soluble. 
This fact is made use of to separate the hexa (and octo) bromo 
deriviaties in carrying out the analytical determination. 


Status: 

The following method is applicable to the determination of 
the hexabromide number of saponifiable oils. It must be re- 
membered that the hexabromide nuniber depends upon the 
method employed in making the determination. It is, there- 
fore, important that in reporting results, the particular 
method must be specified. | eae 


Reagents and Apparatus: 
(a) Reagents: 
(1) C. P. sodium hydroxide solution of 1.4 sp. gr. 
(2) 95% alcohol. 
(3) Distilled water. 
(4) C. P. hydrochlorie acid. 
(5) CO, or nitrogen. 
(6) C. P. bromine containing no non-volatile matter. 
(7) Glacial acetic acid showing no reduction with 


dichromate or permanganate in the usual test. 
(8) Wash ether. 


REFERENCES.—The following are the recent references of value: Chem. 
Tech. and Anal. of Oils, Fats and Waxes, by Lewkowitsch, 5th Ed., Vol. I, p. 
568; Farben Zeitung (1912) No. 3 ff.; Muggenthaler, Inaug. Dissert. 1912. 
Augsburg: Bailey and Johnson, J. I. E. Wal 10, 999 


Shake ordinary ethyl ether with 10% of its volume of ice- 
cold distilled water. Separate the water and repeat the wash- 
ing three times. Dry the washed ether with fused calcium 
chloride over night. Decant the ether through a folder filter 


422 Analysis of Paint Oils 


into another flask and add thin slices of sodium. Warm gently 
on a steam bath under a reflux condenser until the evolu- 
tion of gas by action of the sodium has practically ceased and 
bits of freshly cut sodium remain bright in the ether. Distill 
the ether into a dry bottle and add an excess (at least 3 grams 
per liter) of finely powdered hexabromide of the fatty acids 
of linseed oil previously prepared. (If no hexabromide is on 
hand from previous determinations, it may be prepared as fol- 
lows: In a centrifuge tube dissolve about five grams of the 
fatty acids of linseed oil in 25 cubic centimeters of ether. 
Place the tube in a freezing mixture and add slowly with shak- 
ing bromine solution until a red color is permanent. Let stand 
for at least fifteen minutes and then whirl the tube in a centri- 
fuge until the precipitate has settled and then pour off the 
ether. Rub up the precipitate with 20 cc. of cold absolute 
ether, whirl in a centrifuge and pour off the wash ether. Re- 
peat the washing with 3 more 20 cubic centimeter portions 
of ether. After drying the hexabromide so obtained is pure 
enough for the preparation of the wash ether.) Shake at in- 
tervals for two or three hours or allow the mixture to stand 
overnight. Then place the bottle in ice water so that the ether 
solution will be at zero or not above 2° C. for at least three 
hours. Decant the ether solution rapidly through a folded 
filter into a dry bottle and keep tightly corked in order to 
prevent the loss of ether by evaporation. 


(b) Apparatus: 


(1) Steam bath. 
(2) Gas burner. 


(3) Iron tripod, ring stand and wire gauze. 
(4) Round bottom flask of 2 liters capacity. 
(5) Separatory funnel, 500 ce. 
(6) Bell jar. 
(7) Well annealed test tubes 5” x 1”. 
(8) 50 ce. burette. 
- (9) Glass stirring rods 6” x 3/16”. 
(10) Glass battery jars. 
(11) Graduated cylinders 10 and 50 ee. capacity for 
weighing out samples 
(13) Centrifuge giving about 3,000 R. P. M. 
(14) A vacuum showing no higher than 40 mm. press- 
ure. 
Determination: 


(a) Preparation of fatty acids—Weigh approximately 50 
grams of oil into a 2 liter round-bottom flask and add 40 ee. 
of NaOH solution (sp. gr. 1.4=36.50% sol.) and 40 ee. of alco- 


Analysis of Paint Oils 423 


hol. Place the mixture on a steam bath and insert a 2-hole 
rubber stopper into the neck of the flask carrying a tube which 
projects into the flask so that its end is just above the liquid. 
Heat for about one-half hour, passing a stream of CO2 through 
the apparatus all the while. Add one liter of hot distilled 
water and boil the soap solution to remove the alcohol, either 
over a free flame or on a steam bath. If a free flame is used 
about one-half hour’s boiling will be sufficient, but it may be 
necessary to insert capillary tubes to prevent bumping of the 
liquid. If the solution is heated on the steam bath, usually 2 
to 3 hours are required. After removing the alcohol, the solu- 
tion is cooled somewhat and then acidified with dilute HCl 
(1:1). Warm the mixture until the fatty acids form a clear 
layer, continuing to pass CO2 through the system all the time. 
The fatty acids are separated from the aqueous layer by means 
of a 500 ee. separatory funnel. The funnel is filled with the 
mixture, and the fatty acids will float on top, and the aqueous 
portion is run off. The remainder of the mixture in the flask 
is added to the funnel and the aqueous portion again run off. 
A brisk stream of CO, is passed into the funnel to replace the 
air. 300 ce. of hot distilled water is added and the mixture 
is vigorously shaken. After the fatty acids collect on top the 
aqueous portion is run off. This washing is repeated until the 
water is neutral to methyl orange, three washings usually 
being sufficient. The warm fatty acids are run into a centri- 
fuge tube (1" x 5”) and whirled for about one minute to collect 
any remaining water at the bottom. They are then filtered by 
decantation on to a folder filter under an evacuated bell jar 
and kept in a well-stoppered bottle. 


(b) Preparation of the hexabromides.—Weigh accurately in 
a weighed contrifuge tube (1” diam. x 5” long) as nearly as 
possible one gram of fatty acids. It was found that in the 
case of linseed oil better results are obtained by keeping the 
weight of the sample as near to one gram as possible, so the 
deviations from this should not be more than plus or minus 
0.02 gram. Dissolve the fatty acids in 25 ee. of the specially 
prepared ether and place the tube in a freezing mixture kept 
at about —d° C. made by adding a little HCl to finely cracked 
ice. Add bromine solution* from a burette at the rate of 
about one or two drops per second, shaking the tube well dur- 
ing the addition until a deep red color is produced. This 
should not be done in direct sunlight. The tube is then al- 
lowed to stand in an ice chest overnight (about 14 hrs.), the 


*5 ec. bromine, 25 ec. glacial acetic acid made up just before use. 


424 Analysis of Paint Oils 
ei eee 


proper ‘precautions: being taken to prevent the loss of solvent 
by evaporation by inserting a stopper. —. 

It is necessary to let the tube stand.for this period: of time 
because in the case of oils which contain only a small amount 
of linolenic acid (soya bean oil is a good example) the precipi} 
tation of the hexabromide proceeds more slowly than in the 
ease of an oil with a larger content of lmolenie. acid eee 
for example). 

Next morning cool the tube by immersion in a bath of 
eracked ice and rub up the precipitate by means of a weighed 
glass rod, being sure to loosen any material adhering to the 
side of the tube. Whirl the tube in a centrifuge till the pre- 
eipitate forms a hard cake on the bottom, cool in the ice bath, 
and decant the ether. Add 20 cc.-of the wash ether previously 
prepared and cooled to 0° C. and Yub up the precipitate with 
the glass rod. Return the tube to the ice bath and when cold 
whirl it in the centr ifuge.- Return the tube to the ice bath and 
then remove the ether by’decantation: Repeat this washing 
twice more. After the last washing incline the tube and ecare- 
fully tap it to spread the hexabromide precipitate part of the 
way up the sides: - Warm the tubein water at 60° C. until most 
of the ether has evaporated, then attach it for 15 minutes to a 
vacuum line showing a:pressure of 30-40 mm. keeping the tem- 
perature around 60° C. Wipe the tube dry and allow it to 
stand in the balance at least 15 minutes before weighing. To 
the weight of the precipitate in the tube add the weight of the 
sight amount adhering to the glass rod. This total weight 
of precipitate multiplied by 100 and divided by the weight of 
fatty acids taken, gives the hexabromide percentage. 

Notes: (1) The fatty acids are used instead of the glycerl- 
esters because the latter give inconcordant results. 

(2) In the case of linseed oil, the weight of the sample 
should be kept as near one gram as possible. 

(3) Care should be exercised in preparing the wash ether 
for if it is unsaturated with hexabromides according to direc- 
tions, the results will be low. 


CO-OPERATIVE WORK ON HEXABROMIDE METHODS 
AS CONDUCTED BY SUB-COMMITTEE It OF 
COMMITTEE D-1, A. 8. T. M. | 

Comments made by the various observers are abstracted 

herewith: | 


S. and P. Waldstein state that when a large per- 
centage of soya bean oil is present in an oil there-is 
formed a large percentage of tetrabromide which may 


Analysis of Paint Oils 425 
a __________ 


not be completely washed out. They recommend in 
such instances to increase the portions of ether to 25 
or 30 ee. or to increase the number of washings to 9 or 
6 in order to overcome high results, 

The chairman of the sub-committee has done some 
experimental work with the idea of developing a 
method of determining the hexabromide value of oils 
volumetrically. It was found that the bromine ab- 
sorption number of the fatty acids of linseed oil-were im 
higher than for soya bean oil in some’ preliminary . 
volumetric work. It is known that the bromine, sub- 
stitution number of linseed oil fatty acids is low while 


TABLE 55 


THE RESULTS OF VARIOUS OBSERVERS WORKING ON LWwo. 
Os ARE GIVEN IN THE TABLE BELOW. . 


HEXABROMIDE VALUES 
Bailey 


Steele-Washburn Method : _ Modifica- 
tion of | 
al a ai . 
. ashburn 
z Ree Be ike Method - 
Oils a go ao) = € 4 
© a . sy ; a 3 34 Sn : 
‘ tie pete Ge say ae ek Be Choe 
‘ omc) o g po = a) =| is) | uu 'g x) bp 
eae re iets ee 8 a2 ee ae ¢ @ 58 
= coj> hes aen © a Mm A = = Oe eat 
100 per cent Pure Raw Linseed Oil.... 45.9 46.4 46.6 45.4 46.0 46.2 46.6 45.4 46.1 40.5 42.7 41.6 
85 per cent Pure Raw Linseed Oil.. 
15 per cent Soya Bean Oil................ } SUES I eae 41.8 39.1 41.9 39.8 41.9, 39.1 40.4 34.9 37.5 Ee 


75 per cent Pure Raw Linseed Oil.. 3 . 
O5 uct cent Gova-Bean Oil.............. : 36.4 38.4 38.2 36.0 37.2 36.1 38.4 36.0 ae 31.5 34.5 33.0 


le Gata theta Raw Linseed Oil.) 30.8 38.4 34.8 30.5 38.8 33.5 34.8° 30.5 32.8 26.7 31.4 29.6 
the fatty acids of soya bean oil have a low addition 
number. Considerable further work, however, will 
be necessary in order to develop a method that will be 
satisfactory. 


Conclusions.—The Steel-Washburn method of determining 
hexabromides has given closely concordant results in the 
hands of several different operators, and is apparently well 
adapted for determining the purity of raw linseed oil. It is 
recommended that further work be carried on with the object 
of shortening the method. 

Through the kindness of Mr. Herbert S. Bailey and Mr. 
Baldsiefen of the Experimental Station, E. I. du Pont de Ne- 
mours & Co.; there are presented herewith two tables (56 
and 57) showing the iodine and hexabromide numbers of raw 
and treated linseed oils, and of soya bean oil, tung oil, and 


426 Analysis of Paint Oils 


TABLE 56.—Jodine and hexabromide numbers of raw and treated 
linseed oil 


OL Iodine . 
Hexabromide No. 
No. Substance No. 
pees Steele Method 
By A j ByB 
553 Linseed oil from North American seed..... 176.2 42 0 
: M 6 oat ee 45. 
sa | 46.3 
553 < S ae 2 2 tS See 46.5 
553 . ttn: 4 : Oo eit ae 46.3 
553 m ose : e 4 + ee ee 43.6 
553 « « ria “ “« “ 5 39.2 
553 Ss Nhat . ‘ EMP Py 39.1 
565 | Linseed oil, commercial refined............ 176.5 44.0 
563 . n Z PAW 65 ee 185.0 43.6 
ee | ee 
574 Linseed oil (Bu. of Stds. sample) RRM en 4: 183.0 47.6 
sa) oe ee 
574 Se haem eae en 
574 « «“ « “ « « | 46.2 
pa | ee 6 
535 | Lins’d oil Ext’d from Argentine seed....... 189.8 50.0 49.7 
535 “ a“ “ “ “ {9 50 8 
pp | ee 
641 OL 553 + 5% (1) tung oil drier 727 166.8251). Ae se 
641 : MC 
“ “& «“ “ “ 
eg |g 
643 ee Se 208, SS, Se 152 6.3]. See 41.8 
643 ait : CO ee ee 42.2 
— 2 " + 5% grinding japan .. 3. see 164,81) ea ones 
64 " : MS elk o oun eh ip Le ee ; 
ey 8 “ +10% ‘ GC oe ae 158.9 eae ee 
5 : - : Opa vee ee L 
ih ; + 20% : pike 147.43 ee ae 
588 « « + 10% (*) linoleate driet..7.meeme "165.6 43.6 
ae ‘S20 : al 45.3 
po |< « eS 
oF 5 “+ 0.2% manganese driert epee tN 168 .6 oie: 
= o> ee OS eee : a 32.6 
561 | Linseed oil, commercial... <3: > .3.eee 17a 41.8 
561 sg “ boiled... 0.00.02. 525.00 5. 5 
359 = “ heavy bodied =...) ae pee 80.8 11.3 


various mixtures thereof. It is believed that the data pre- 
sented in these tables will be of great service to the paint 
chemist who intends to carry on hexabromide work. 


(*) Added without treating oil. 
(+) Manganese linoleate boiled in at 250° C. 


Analysis of Paint Oils 427 
ee ER AR a, el 


TABLE 57.—lodine and hexabromide numbers of soya bean, tung and lin- 
seed-soya bean mixtures 


$y CE 
os os 
BE ee Fae 
Ceara: ea 
i) 
OL a eee Vee sser ES 
as Bo S38 
No. ubstance £5 2s : e 
< ss 
; By A By B. | By B. 
310 | Soya bean oil, raw................ 13322 bet G5 4.2 
310 . | SS Oe keer eeeeiae eS he SAN terre acs 4.9 
310 pan Rete ere CO eng oes 3.6 
565 | Soya bean oil, raw commercial. .... 133.2 1.5 
565 <3 he Namie ooh ig SRE CNet Fc Saye 5.0 
658 : Baer pressed. yo... |. ci cc ule nc ces 8.41 (OP#s 
658 y: Depa Deere ea es ne. na ee 9.38 7.54 
G59 | Soya bean oil, cold pressed........|........|........ 5.95 5.35 
659 : emer © ST . Csce VER On Raga ctel aR ee a 5.76 5.65 
Grove Hean oil,,extracted..:........|......00c)oc 00... 3.9 
Se STE a ee De 0.0 0.0 
572 50% OL 553 + 50% OL 310....|........ 26.0 23.0 
572 Abe © rte ts ian Pea) nc et 23.6 
572 50% OL 553 + 50% OL 670....|........ ee 24.3 23.3 
572 7 ee OE Ele RO SiR atte Ee 24.6 24.3 


A. 8. T. M. TENTATIVE SPECIFICATIONS FOR 


RAW TUNG OIL 


I. PROPERTIES AND TESTS. 
1. Raw tung oil shall conform to the following requirements: 
Maximum. Minimum. 


Specific gravity at SIDA Wis Ry ain BIR eee SP anaes ea 0.943 0.9400 
Acid number (Alcohol-Benzol)................: 8.0 eee 
Mme 110) ONNMDET... 2... eae che sae eae 195 190 
Unsaponifiable matter, per cent................ 0.75 ba gan 
Peeremetive Indes. at 25° OC... . ices ccs e cee cseas 1.520 1.5165 
Peer uinver (WijS) 2... 02k. sce cos coke ccc elelee sake 163 
Demme tet MINUTOS, . 0... ce et ee wens cee 12 Pamels 


II. METHODS OF TESTING 
SOLUTIONS REQUIRED 


2. The following reagents will be required: 

Standard Sodium Thiosulfate Solution—Dissolve pure sodium thiosulfate 
in distilled water that has been well boiled to free it from carbon dioxide in 
the proportion so that 24.83 g. crystallized sodium thiosulfate will be present 
in 1000 ce. of the solution. It is best to let this solution stand for about two 
weeks before standardizing. Standardize with pure resublimed iodine. (See 
Treadwell-Hall, Analytical Chemistry, Vol. II, third edition, p. 646.) This 
Solution will be approximately N/10 and it is best to leave it as it is after 


428 Analysis of Paint Oils 


determining its exact iodine value, rather than to attempt to adjust it to 
exactly N /10 strength. Preserve in a stock bottle with a guard tube filled 
with soda lime. 


Starch Solution.—Stir up 2 to 8 g. of potato starch of 5 g. soluble starch 
with 100 cc. of 1-per-cent salicylic acid solution, add 300 to 400 cc. boiling 
water, and boil the mixture until the starch is practically dissolved. Dilute 
to 1 liter. 

Potassium Todide Solution.—Dissolve 150 g. of potassiuin iodide free from 
iodate in distilled water and dilute to 1000 ce. 


Iodine-Monochloride Solution.—Dissolve iodine in glacial acetic acid that 
has a melting point of 14.7 to 15° C. and is free from reducing impurities in 
the proportion so that 13 g. of iodine will be present in 1000 ec. of the soiu- 
tion. The preparation of the iodine-monochloride solution presents no great 
difficulty, but it shall be done with care and accuracy in order-to obtain satis- 
factory results. There shall be in-the solution no sensible excess either of 
iodine or more particularly of chlorine, over that required to form the mono- 
chloride. This condition is most satisfactorily attained by dissolving in the 
whole of the acetic acid to be used the requisite quantity of iodine, using A 
gentle heat to assist the solution, if it is found necessary. Set aside a small 
portion of this solution, while pure, and pass dry chlorine into the remainder 
until the halogen content of the whole solution is doubled. Ordinarily it will 
be found that by passing the chlorine into the main part of the solution until 
the characteristic color of free iodine has just been discharged, there will be 
a slight excess of chlorine, which is corrected by the addition of the requisite 
amount of the unchlorinated portion until all free chlorine has been destroyed. 
A slight excess of iodine does little or no harm, but excess of chlorine must 
be avoided. 


Chloroform.—Should be U. S, P. 


Standard Sodium Hydroxide Solution.—Prepare a stock concentrated solu- 
tion of sodium hydroxide by dissolving NaOH in water in the proportion of 
200 g. NaOH to 200 ce. water. Allow this solution to cool and settle in a 
stoppered bottle for several days. Decant the clear liquid from the precipi- 
tate of sodium carbonate into another clean bottle. Add clear barium hydrox- 
ide solution until no further precipitate forms. Again allow to settle until 
clear. Draw off about 175 ce. and dilute to 10 liters with freshly boiled dis- 
tilled water. Preserve in a stock bottle provided with a large guard tube 
filled with soda lime. Determine the exact strength by titrating against pur 
benzoic acid (C,H;COOH) using phenolphthalein as indicator. (See Bureau 
of Standards Scientific Paper No. 183.) This solution will be approximately 
N /4; but do not attempt to adjust it to any exact value. Determine its exact 
strength and make proper corrections in using it. 


Alcoholic Sodium Hydroxide Solution.—Dissolve pure NaOH in 95-per-cent 


ethyl alcohol in the proportion of about 22 g. per 1000 ce. Let stand in a 


stoppered bottle. Decant the clear liquid into another bottle, and keep well 
stoppered. This solution should be colorless or only slightly yellow when 
used; it will keep colorless longer if the alcohol is previously treated with 
NaOH (about 80 g. to 1000 ec.), kept at about 50° ©. for 15 days, and then 
distilled. For an alternate method see Journal, American Chemical Society, 
1906,-p. 395: 


ait 


os ; 
2 ee 
ey eee ee ee ee 


Analysis of Paint Oils 429 


Half Normal Sulfuric Acid Solution—Add about 15 ce. HoSO,4 (sp. gr. 
1.84) to distilled water, cool and dilute to 1000 cc. Determine the exact 
strength by titrating against freshly standardized NaOH or by any other 
accurate method. Hither adjust to exactly N /2 strength or leave as originally 
made, applying appropriate correction. 


METHODS 

3. The oil shall be tested in accordance with the following methods: 

General.—The laboratory sample shall be thoroughly mixed by shaking, 
stirring, or pouring from one vessel to another and the samples for the in- 
dividual tests taken from this thoroughly mixed sample. 

Specific Gravity.—Use a pyknometer accurately standardized and having 
a capacity of at least 25 cc., or any other equally accurate method, making 
the test at 15.5° C., water being 1 at 15.5° C. 

Acid Number.—Weigh from 5 to 10 g. of the oil. Transfer to a 300-cc. 
Erlenmeyer flask. Add 50 cc. of a mixture of equal parts by volume of 95- 
per-cent ethyl alcohol and ec. p. reagent benzol. (This miature should be 
previously titrated to a very faint pink with dilute alkali. solution, using 
phenolphthalein as an indicator.) Add phenolphthalein indicator and titrate 
at once to a faint permanent pink color with the standard sodium hydroxide 
solution. Calculate the acid number (milligrams KOH per gram of oil). 

Saponification Number.—Weigh about 2 g. of the oil in a 300-cce. Erlen- 
meyer flask. Add 25 cc. alcoholic sodium hydroxfde solution. Put a con- 
denser loop inside the neck of the flask and heat on the steam bath for one 
hour. Cool, add phenolphthalein as indicator, and titrate with N/2 HySOq. 
Run two blanks with the alcoholic sodium hydroxide solution. These should 
eheck within 0.1 cc. N/2 H.SO,. From the difference between the number of 
cubic centimeters of N /2 H.SO, required for the blank and for the determina- 
tion, calculate the saponification number (milligrams KOH required for 
eof the: oil). 

Unsaponifiable Matter—Weigh 8 to 10 g. of the oil. Transfer to a 250-ce. 
long-neck flask. Add 5 cc. of strong solution of sodium hydroxide (equal 
weights of NaOH and H.O), and 50 ce. 95-per-cent ethyl alcohol. Put a con- 
denser loop inside the neck of the flask and boil for two hours. Occasionally 
agitate the flask to break up the liquid but do not project the liquid onto the 
sides of the flask. At the end of two hours remove the condenser and allow 
the liquid to boil down to about 25ec. 

Transfer to a 500-cc. glass-stoppered separatory funnel, rinsing with water. 
Dilute with water to 250 cc., add 100 cc. redistilled ether. Stopper and shake 
for one minute. Let stand until the two layers separate sharp and clear. 
Draw all but one or two drops of the aqueous layer into a second 500-ce. 
separatory funnel and repeat the process, using 60 ce. of ether. After thor- 
ough separation draw off the aqueous solution into a 400-ce. beaker, then the 
ether solution into the first separatory funnel, rinsing down with a little 
water. Return the aqueous solution to the second separatory funnel and 
shake out again with 60 cc. of ether in a similar manner, finally drawing the 
aqueous solution into the beaker and rinsing the ether into the first sepera- 
tory funnel. 

Shake the combined ether solution with the accumulated water rinsings 
and let the layers separate sharp and clear. Draw off the water and add it 


430 Analysis of Paint Oils 


to the main aqueous solution. Shake the ether solution with two portions of 
water (about 25 ce. each). Add these to the main water solution. 

Swirl the separatory funnel so as to bring the last drops of water down 
to the stopcock, and draw off until the ether solution just fills the bore of 
the stopcock. Wipe out the stem of the separatory funnel with a bit of 
cotton on a wire. Draw the ether solution (portionwise if necessary) into a 
250-cce. flask and distill off. While still hot, drain the flask into a small 
weighted beaker, rinsing with a little ether. Evaporate this ether, cool and 
weigh. 


NotEe.—The unsaponifiable oil from adulterated drying oils is volatile and 
will evaporate on long heating. Therefore heat the beaker on a warm plate, 
occasionally blowing out with a current of dry air. Discontinue heating as. 
soon as the odor of ether is gone. 


Refractive Index.—Use a properly standardized Abbé refractometer at 25° 
C., or any other equally accurate instrument. 

Iodine Number.—Place a small quantity of the sample in a small weighing 
burette or beaker. Weigh accurately. Transfer by dropping from 0.16 to 0.19 
g. to a 500-cc. bottle having a well-ground glass stopper, or an Erlenmeyer 
flask having a specially flanged neck for the iodine tests. Reweigh the 
burette or beaker and determine the amount of sample used. Add 10 ce. of 
chloroform. Whirl the bottle to dissolve the sample. Add 10 ec. of chloro- 
form to each of two empty bottles like that used for the sample. Add to 
each bottle 25 cc, of the Wijs solution and let stand with occasional shaking 
for 380 minutes in a dark place at a temperature of from 21 to 23° CG. Add 
10 ce. of the 15-per-cent potassium iodide solution and 100 ce. of water, and 
titrate with standard sodium thiosulfate using starch as the indicator. The 
titrations on the two blank tests should agree within 0.1 ec. From the dif- 
ference between the average of the blank titration and the titration on the 
samples and the iodine value of the. thiosulfate solution, calculate the iodine 
number of the samples tested. (Iodine number is given in centigrams of 
iodine to 1 g. of sample.) * 

Heating Test——Test tubes containing the oil should -be 15 cm. by 16 mm., 
with a mark near the bottom to indicate 5 ce., and closed by a cork so per- 
forated that a glass rod 8 mm. in diameter can move freely. 

Fill an 800-ce. glass beaker (height, 13 em.; diameter, 10 em.), with cotton- 
Seed oil or soya bean oil to a height of 7.5 cm. Place a thermometer so as to 
be 1.5 cm. from the bottom of the bath. (See Fig. 178.) 

Use a nitrogen-filled, chemical thermometer; engraved stem; total length 
4 to 4% in., graduated from 210 to 310° C. in 2° intervals; the length between 
210 and 310° C. not less than 214 in. Thermometer glass shall be well 
annealed. 

When the bath temperature is 293° C. (560° F.) and very slowly rising 
at this point, place the tube containing 5 ce. of the oil to be tested and the 
tube containing 5 ce. of a control sample of known value, so that the bottom 
of each tube is level with the lowest part of the bulb of the thermometer. 
If desired, the collars C may be omitted and the tubes allowed to rest upon 


*It is always well to include a test on a sample of tung oil of known iodine 
value. This may be kept in a dark-colored bottle as a standard. 


Analysis of Paint Oils 431 


oe. Sample eet po: ; 


Cottonseed or : 3 
Soya Bean _y ue ci 
Oj] -------+°" i 2 Bae dee Soot ee 10 Cae ae 


Vertical Section. 


— SPECIFICATIONS — 
A. Beaker Glass 800 cc. D. Test Tubes, IScm.x 16mm. 
8B. Cover Plate (Iron or Wood.) E. Thermometer~ Small Range. 


C. Collar Support (Rubber F. Glass Rods, (3mm. with 
Stopper No. 6.) Cork Stoppers.) 


FIGURE 178 


Tung Oil Heat Test Apparatus (Revised 1920). 


Nore: Collars 0 may be omitted and tubes supported in present place by 


aid of wire gauze placed in bottom of oil bath and resting on bottom of beaker. 


432 Analysis of Paint Oils 


a piece of wire gauze placed in the bottom of the oil bath so that the tubes 
will be 1.5 cm. from the bottom of the bath. Note the time. Remove the 
source of heat for about 45 seconds and then reapply. Before 2 minutes 
have elapsed the temperature of the bath will have fallen to 282° C.. {5807 Pas 
at which point it should be kept as steady as possible. When the samples 
have been in the bath 9 minutes, raise the glass rods at intervals of 14 minute. 
Note the time when each sample becomes firmly set. At this period the oil 
will be so stiff that the entire tube may be lifted by aid of the rod if the 
collar C is omitted from the apparatus. As setting or jellying takes place 
within a few seconds of fluidity, a good end determination is afforded. 
Remove the specimens. Heat the bath again to 293° C., and repeat the 
experiment with fresh portions of the sample. 

No stirrer is used in the bath. A sereen around the bath enables the 
temperature to be more easily reached. When the bath oil has become tarry 
and viscid, it should be renewed; otherwise heating may be irregular. 

Quality Test*—Into an ordinary agateware casseroce, having a bottom 
diameter of 3 in., weigh 150 ¢. of the tung oil to be tested, and set the casse- 
role on a wide-flanged tripod having a 3-in. opening. The object of the flange 
is to prevent super-heating of the sides of the casserole. Heat rapidly with 
a full Bunsen flame, stirring with a thermometer, until the heat reaches 
540° BF, (282:2° Cc.). Turn down the flame and hold the heat as near 
540° F, (282.2° C.) as possible, stirring with the thermometer, until on lifting 
the latter the oil drops with a pronounced string, showing that polymerization 
has started. The time required after reaching 540° F. (282.2° C.) until the 
string is noted, is the time of the heat test. For pure tung oils this will not 
exceed eight minutes. As soon as the oil strings, remove the lamp and the 
thermometer, and stir with a stiff spatula until the oil is solid. After string- 
ing, a pure tung oil will require not over 40 seconds more to become solid. 
When solid, allow to stand just one minute, then turn out, upside down, on 
clean paper and cut with a clean spatula. Pure tung oil gives a gel that is 
dry, not adhering to the spatula when cut, that is firm, crumbling under 
pressure of the spatula without sticking, and the cut portions should crumble 
under pressure like dry bread crumbs. Adulterated tung oil gives a gel that 
is soft; sticky, and which will not crumble. 


Ill... SAMPEING 
The method of sampling given under Method (@) below shall be used 
whenever it is feasible to apply it. To meet conditions when (a) is not 
applicable, method (0) or (¢) shall be used, according to the special condi- 
tions that obtain. 
(a) During Loading of Tank Cars or Filling of Containers for Ship- 
ment.— 
. The purchaser’s inspector shall draw a sample at the .discharge pipe 
where it enters the receiving vessel or vessels. The totai sample shall be 
not less than 1 gal. per each tank car or 10,000 gal. equivalent, and shall be 
a composite of small samples of not more than 1 pt. each taken at regular 
intervals during the entire period of loading or filling. 


* Furnished by R. 8S. Worstall. 


Analysis of Paint Oils 433 


The sample thus obtained shall be thoroughly mixed, and from this com- 
posite sample three portions of not less than 1 qt. each shall be placed in 
clean, dry glass bottles or tin cans, which must be filled with the sample and 
securely stoppered with new clean corks or well-fitting metal covers or cans. 
These shall be sealed and labeled distinctly by the inspector, one delivered to 
the buyer, one to the seller and the other held for check in case of dispute. 

(b) From Loaded Tank Cars or Other Large Vessels.— 

The total sample shall be not lessi than 1 gal. per each tank car or 10,000 
gal. equivalent, and shall be a composite of numerous small samples of not 
more than 1 pt. each., taken from the top, bottom, and intermediate points by 
means of a glass or metal container with removable stopper or top. This 
device attached to a suitable pole is lowered to various desired depths when 
the stopper or top is removed and the container allowed to fill. The sample 
thus obtained shall be handled as in Method (a). For large shipments in 
freighters ranging from 400 to 1000 tons, first draw samples from the top 
and bottom of both port and starboard sections of the tank. These samples 
shall be visually examined, and if the general appearance gives indications 
that the oil is satisfactory, pumping shall be started and 1-pt. samples drawn 
from a bleeder in the discharge line at least once in every thirty minutes, 
so that the total mixed sample amounts to as many gallons as there are 
units of 10,000 gal. in the cargo. These individual samples are composited 
to make one uniform sample representative of the “entire cargo and this is 
handled as in Method (a). | 

(ec) Barrels and Drums.— 

Not less than 10 per cent of the packages in any shipment or delivery of 
barrels and drums shall be sampled. The packages shall be shaken, rolled, 
and stirred to thoroughly mix the contents. The samples from the individual 
containers shall be taken through the bung hole or holes not less than 114 in. 
in diameter bored in the head or side for the purpose. The apparatus for 
drawing the sample shall consist of a glass tube (known as a thief) about 
1 in. in diameter and somewhat longer than the length or diameter of the oil 
container, a conical stopper that will fit the glass tube and is not more than 
% in. in length, fastened to a stiff metal rod not more than 14 in. in diameter 
and not less than 4 in. longer than the glass tube. The stopper is lowered by 
the rod until it rests on the bottom of the cask, the tube slipped down slowly 
over the rod, and finally pressed on the stopper. By holding the tube and the 
rod, the column of oil can then be removed. This process is repeated until 
the required amount of sample is obtained, which shall be not less than 1 gal. 
This is mixed and handled as in Method (a). During the winter when the 
oil is very often in a solid condition, the same procedure should be followed, 
replacing the thief with a tallow trier, which is essentially a graduated piece 
of steel tubing semi-circular in cross-section and about 3 ft. long. This is 
pushed into the oil, turned a few times and withdrawn, thereby removing a 
solid core of oil. 


It has been found that the optical dispersion of tung oil is 
extremely high as compared to that of many other oils. Based 
on this, Holley has worked out a method to determine the 
purity of tung oil (Holley, Analysis of Paint Vehicles, 1920, 


434 Analysis of Paint Oils 


p. 81). This method, however, is not commonly in use be- 
ae of the expense and difficulty of obtaining the type of 
apparatus used for the purpose. It is believed, nevertheless, 
that optical dispersion methods are of great value for the ex- 
amination of tung oil and that they should be used when the 
apparatus and instruments are available, as additional or 
confirmatory tests. Asa rule, determination of specific grav- 
ity, refractive index, and quality tests, as outlined above, 
afford sufficient Snformatien to judge the purity and value of 
tung’ oil. 

See also quantitative method for detecting tung oil on page 
694. 


Optical Dispersion Test for Tung Oil.—As a means of 
determining the purity of Tung Oil, optical dispersion con- 
stants have recently become important. Considerable work 
was done on this subject in 1912 by Potsdamer, who found that 
it was exceedingly difficult to adulterate Tung Oil so that the 
refractive index, specific gravity and dispersion were un- 
changed. Apparently this method has been used quite widely 
in China by brokers who purchase oil in quantity for export 
to America. In the test the refractive index is ordinarily 
determined on the D line of the sodium light. In the modern 
Abbe refractometer, instead of sodium light, ordinary white 
day light may be used, the achromatizer being made so as to 
give the same reading as would be obtained with sodium 
light. By the use of charts which accompany each instrument 
the dispersion of an oil may be calculated. 

Toch has recently given much consideration to this subject 
and in the Third Edition of his book entitled ‘‘The Chemistry 
and Technology of Paints’’* he presents many tables show- 
ing the characteristics of China wood oil adulterated with 
from 5 to 15 per cent of various other oils. In a personal 
communication to the writer, Toch states that he has never 
found pure Tung Oil with a refractive index less than 1.5176 
and a dispersion value less than 0.02025—both readings at 
21.5° C. Some of the results given by him are as follows: 


Sp. Gr. Ref. Ind. Dispersion 


Oil 60°F. 21.5°C. 21.5°C. 
Chinese wood oil, \J.. M.-C... <05 ssc saree 0.938 1.5181 0.02073 
Chinese wood oil, M. A. F.C0.. 6. 30250 sous cee 0.939 1.5183 0.02074 
Light parafiin (Of) 06.0) < seve ye en ae ee ee 0.874 1.4870 0.01158 
Sova, bean. OU ks. uss 8 Ss Pe ee av ee eee 0.944 1.4760 0.01027 
Refined linseed. Olb.i'ic ccd nnn kaneis wale SU 0.933 1.4796 0.01078 


*D. Van Nostrand & Co., N. Y. 


Analysis of Paint Oils 435 


I ice ke sccs cee sesesis® (ae GiR Sattoname cate 0.940 1.4753 0.01008 
a 0 a 0.934 1.4821 0.01062 
EIEN ON ac e oc l6. ines sk eee vce t ys ne os 0.936 1.4822 0.01114 
Ne eka ccs ve ce sate sceseces 0.933 1.4713 0.00971 
I ete fo. aon ogc se oe 80 6 5 sie we ee we es 0.939 1.4816 0.01036 
IT PUL, ccs cg tek ce sc nesceecsscees 0.913 1.4695 0.00927 
CT We ies eels oc vn see bcc cece ces esepe 0.949 1.4860 0.01092 
SOE a SS ee 0.922 1.4720 0.009897 
MUP MINISERO IG Soc science isles sccascecasesese 0.914 1.4734 0.009894 


TESTS ON SAMPLE I. J. M. C. CHINESE WOOD OIL 


Oil Sp. Gr. Ref. Ind. Dispersion 

60°F. 21,5° GC, PA Rate Bh 

eevee 10% paraflin oil ......cccescccces 0.932 1.5149 0.01064 
ee emermriMis 10% -SOya. bean: Oil.......5...... 0.938 1.5139 0.01951 
eevee ais 1005 linseed oil .. 2... cece ese on 0.937 1.5143 0.01976 
eee errony ete 20 PEriliqg Ol oo... 0. eee ecw eee 0.936 1.5145 0.01976 
eens 10> COIN Oil 26... ccc tee cee 0.938 1.5140 0.01977 
C. W. O. plus 10% menhaden oil ............... 0.938 1,5138 0.01977 
ey eres 10S Stillingia O11 .......s.sceee0 0.937 1.5146 0.01990 
Merwe emis 100% peanut’ Oil ........c0.0cee ees 0.938 1.5136 0.01983 
ew ees 100, tea seed Oil...........- 00008 0.936 1.5135 0.01970 
C. W. O. plus 10% tallow seed oil (Hankow)... 0.9438 1.5167 0.01978 
(.W. o. plus 10% cotton seed oil.............. 0.938 1.5138 0.01962 
oye emis 19 rape seed. oll. ..:...... 5.000 0.936 1.5139 0.01982 


Solubility of Tung Oil Polymer Purity Test.—K. R. Bolton 
and K. A. Williams have recently submitted to the writer a 
copy of their paper which originally appeared in The Analyst. 
This paper describes a very interesting method of differentiat- 
ing between samples of pure and adulterated tung oil, based 
upon the solubility of the polymer. The test as submitted is 
given below. 


The test now proposed has for its aim the separation, by 
solvent extraction, of the adulterating oil from the mass ob- 
tained on polymerising the oil by heat. Such separation has 
been attempted on previous occasions by others, but seems to 
have failed, owing to incomplete polymerisation of the tung 
oil, due to the nature of the method used for effecting poly- 
merisation. 


Chapman* has already expressed the opinion that Wor- 
stall’s polymerisation test, when carried out in the manner 
originally described, is unsatisfactory, in which opinion the 
present authors concur. It has been found, however, that the 
following modification of Worstall’s test gives a satisfactory 
and evenly-polymerised mass. 


* Analyst 37, 453 (1912). 


436 Analysis of Paint Oils 


Modification of Worstall’s Test—One hundred and fifty 
orms. of the oil, contained in a stout aluminum beaker, exactly 
3 inches in diameter and approximately 4 inches in height, are 
heated by means of a Bunsen burner so as to reach a tempera- 
ture of 285° C. in approximately 4 minutes, the oil being vig- 
orously stirred by means of the thermometer during the oper- 
ation. 


As soon as the temperature of the oil has reached 285° C. 
a stop-watch is started, and the temperature of the oil is 
thereafter maintained as nearly as possible at 285° C., the 
stirring being continued all the time. The time is noted when 
polymerisation suddenly sets in, as is indicated by the failure 
of the oil to drop from the thermometer when the latter is 
raised from the bath. Genuine tung oils reach the stage de- 
scribed after less than 8 minutes’ heating at 285° C. 


If a long-stemmed thermometer be used, a stem correction 
must be applied. <A variation of 3° C. from standard tempera- 
ture throughout the polymerisation will cause a difference of 
as much as one minute in the time of polymerisation with some 
specimens of tung oil. 


A genuine tung oil of good mercbartann quality produces a 
dry, firm gel having a pale yellow colour and a characteristic 
appearance and texture. 


Extension of the Modification—The authors have extended 
this modification of Worstall’s test as follows: A portion of 
approximately 2 grms. is taken from the center of the poly- 
merised mass and weighed into a mortar to which are added 
about 3 grms. of dry ‘‘silver’’ sand and 2 ml. of petroleum 
spirit. The mixture contained in the mortar is now carefully 
incorporated with a pestle and ground until the petroleum 
spirit has, for the most part, evaporated. The bulk of the 
mixture is now transferred to an extractor, the mortar thor- 
oughly washed with petroleum spirit into the extractor, and 
the extraction carried on in the usual manner. In these 
circumstances tung oils are found to give an extract of 28 
per cent. with a variation not exceeding 2 per cent. on either 
side. 


A large number of different tung oils have been tested in 
this manner, with the result that in no case did any authentic 
sample give more than 30 per cent. of extract, provided that 
the polymerisation had been carried out at a temperature 
above 275° C. The fact that polymerisation is not completed, 
by the method proposed, at lower temperatures is shown by 
the following table: 


a 


Analysis of Paint Oils 437 


Temperature Time for polymerisation Extract 
2c: Minutes Per Cent. 
310 3.10 28.35 
285, 7.25 28.25 
268 13.50 42.20 
250 21.75 08.10 


Results with Adulterated Oils—In the case of adulterated 
oils the whole of the adulterant is obtained in the extract, to- 
gether with a small proportion of unpolymerised tung oil, 
except in the case of tung oil adulterated with linseed oil, 
which yields after polymerisation approximately half the 


weight of the adulterant in the extract; this is exemplified 
by the following table: 


. Time for Theoretical* 
Foreign Oil. Tung Oil. Polymerisation. Extract. Extract. 
Per Cent. Per Cent. Minutes. Per Cent. Per Cent. 
Semi-drying oil (soya) 
0 100 7.5 29.4 29.4. 
5 95 8.0 33.4 o chk 
10 90 9.0 37.4 36.6 
20 80 14.0 45.0 43.5 
33 67 20.0 55.5 53.0 
50 50 57.0 68.5 64.6 
67 33 400.0 79.4 77.0 
Tung oil acids 
10.5 89.5 10.0 38.1 37.0 
Linseed oil 
0 100 Lo 29.0 29.0 
5 95 8.0 31.4 33.0 
10 90 8.5 83.1 36.6 
50 50 45.0 48.4 64.6 


As shown in the fourth and fifth columns of the above 
table, the free fatty acids of tung oil do not polymerise; con- 
Sequently, when these are present in any quantity over 2 per 
cent., allowance must be made in computing the amount of 
an adulterant (cf. Jameson, Analyst, 1920, 45, 328). 


The proportion of adulterant present may be calculated 
from the following formulae: 


If the adulterant is not linseed oil or drying oil of high 
iodine value: 

Foreign oil per cent. = (extract per cent. — 30.0) X 1.33. 

If the adulterant is linseed oil: 

Foreign oil per cent. = (extract per cent. — 30.0) x 2.70. 

By means of the test now proposed, in conjunction with the 
refractive index of the original oil, it can readily be decided 


*The figures in the last column are calculated on the assumption that the 
tung oil present is polymerised to the Same extent as pure tung oil would be, 


and that none of the foreign oil in the mixture is polymerised or rendered 
insoluble in petroleum Spirit. 


438 Analysis of Paint Oils 


whether the adulterant consists of linseed oil or not, and, in 
most cases, a clear idea of the nature of the adulterant is 
given. 

The commercial value of tung oil presumably bears a direct 
relationship to the amount of polymerisable matter it contains, 
and, consequently, a test which measures this main constituent 
and separates non-polymerisable matters must surely give a 
better commercial valuation of the oil than any consideration 
of ‘‘constants’’ or ‘‘variables.”’ 


Accelerators for the Production of Beta Elaeostearin.—In 
Scientific Section Circular No. 256 is given information re- 
garding the production of beta elaeostearin from tung oil 
through the action of light. Small percentages are induced 
by long periods of exposure to sunlight. It is pointed out 
in that circular that small amounts of sulphur will very rapidly 
stimulate the production of beta elaeostearin. Some more 
recent tests show the results obtained when from .02 per cent 
to 5.0 per cent of ‘‘flowers’’ of sulphur are stirred into tung 
oil and exposed to diffused hight in a room for a period of 
from 48 hours to one week: 


Percentage of Yield.after Yield after 
No. sulphur. 48 hours 1 week 
1 02 None 23.5% 
2 Al None 34.5% 
3 1.0 26% ; 39.5% 
4 2.0 32% 45.5% 
5 5.0 28% 49% 


The results given above may be of general interest to the 
chemist who desires to produce beta elaeostearin in substantial 
amounts in a short period of time. 


It may be of further interest to state that large deliveries of 
tung oil to three very prominent paint and varnish manufac- 
turers during the past year have shown the presence of very 
substantial amounts of beta elaeostearin. In one instance, the 
percentage was so great as to interfere with the factory utiliza- 
tion of the product. In another instance, the oil which was 
extremely cloudy and contained a marked amount of separated 
crystalline matter, was used up in the factory without diffi- 
culty. More rapid polymerization was observed in the kettle. 


Analysis of Paint Oils 439 


In the third instance, the polymer was formed at the top of the 
storage tank to a depth of about eight inches. Upon removal 
of this in a sample which was subsequently exposed to hght, 
another quantity of the polymer soon developed. Examina- 
tion of the oil in the laboratory when received, and at a period 

two months later, indicated a rise in acid value from 4.86 to 
6.20, a rise in gravity from 0.9410 to 0.9414, a rise in refractive 
index from 1.5185 to 1.5187, and a drop in the time of poly- 
merization from 1114 minutes to 914 minutes. 

The writer has suggested that shipments of tung oil in the 
hulls of incoming steamers might be affected by the presence 
of traces of sulphur in the hulls of the steamers, if they had 
previously been used for carrying pyrites, brimstone, or simi- 
lar cargoes containing materials which would stimulate the 
formation of beta-elaeostearin. ‘ 

F’. W. Hopkins* has referred to a shipment of approximately 
8,000 gallons of tung oil received in the winter of 1925. The 
tank car was heated and the oil conveyed to a storage tank 
in a room having a temperature of approximately 85° F. Two 
months later, a sponge-like polymer was observed at the top 
of the tank, extending into the oil to a depth of six or eight 
inches, while the oil in the bottom of the tank was in a sem1- 
liquid condition. In the Browne heat test an original sam- 
ple from the tank car showed 11% minutes, whereas a sample 
from the bottom of the storage tank after two months’ storage 
showed only 914 minutes. Hopkins refers to the possibility 
of the development of changes in the oil over this period of 
time, and found present 12.5% of beta elaeostearin. 


A. 8. T. M. TENTATIVE SPECIFICATIONS FOR 


SOYA BEAN OIL, RAW OR REFINED 


1. PROPERTIES AND TESTS. 


1. Soya bean oil, raw or refined, shall conform to the following require- 
ments: 


MAXIMUM, MINIMUM 
TS m0 
Loss on heating at 105 to 110° C, per cent...... 0.2 eae 
Specific gravity at pe PG 0. he en ee ae, aye 0.924 
SMNDTRRE e e bb ie ee ce ccs 5.0 ike 
Bepeereation NUMbEr .. 0... keke ees cccccen. Pee 190 
See ainer “(LIANUS) oo. s. e e e ccc nue cate. Mae 128 


*“A Phenomenon to be Considered in the Purchase of China Wood Oil.” 
Scien. Sec. Cire. 297. 


440 Analysis of Paint Oils 
MAxIMUM MINIMUM 
Unsaponifiable matter, per cemt.....-++++++eee- 1.5 i Ph 
COlOM. ss su.ne enue an leh ae ts clapind <)s) Onl epnege kl ceeraeae Not darker than a freshly 


prepared solution of 
1.0g. potassium bichro- 
mate in 100 cc. pure 
H,SO, (sp. gr. 1.84). 


II. METHODS OF TESTING. 
SOLUTIONS REQUIRED. 


2 The following reagents will be required : 

Acetone that will pass the specification of the United States Pharmacopoeia. 

Acid Calcium Chloride Solution.—Saturate with calcium chloride a mixture 
of 90 parts water and 10 parts HCl (sp. gr. 1.18). 

Standard Sodium Thiosulfate Solution.—Dissolve pure eodtas thiosulfate 
in distilled water that has been well boiled to free it from carbon dioxide in 
the proportion so that 24.88 g. cry stallized sodium thiosulfate will be present 
in 1000 cc. of the solution. It is best to let this solution stand for about two 
weeks before standardizing. Standardize with pure resublimed iodine. (See 
Treadwell-Hall, Analytical Chemistry, Vol. I, third edition, p. 646.) This 
solution will be approximately N/10 and it is best to leave it as it is after 
determining its exact iodine value, rather than to attempt to adjust it to 
exactly N/10 strength. Preserve in a stock bottle with a guard tube filled 
with soda lime. 

Starch Solution.—Stir up 2 to 3 g. of potato starch or 5 g. soluble starch 
with 100 cc. of 1-per’cent salicylic acid solution, add 3800 to 400 ce. boiling 
water, and boil the mixture until the starch is practically dissolved. Dilute 
to 1 liter. 

Potassium Iodide Sornsons —Dissolve 150 g. of PELE iodide Rie from 
iodate in distilled water and dilute in 1000 ce. 

Hanus Solution.—Dissolve 13.2 g. of iodine in 1000 ce. of glacial acetic acid 
(99.5-per-cent) that will not reduce chromic acid. Add enough bromine to 
double the halogen content, determined by titration (38 ce. of bromine is about 
the proper amount). The iodine may be dissolved by the aid of heat, but the 
solution should be cold when the bromine is added. 

Standard Sodium Hydroxide Solution.—Prepare a stock concenttrated solu- 
tion of sodium hydroxide by dissolving NaOH in water in the proportion of 
200 g. NaOH to 200 ce. water. Allow this solution to cool and settle in a 
stoppered bottle for several days. Decant the clear liquid from the precipitate 
of sodium carbonate into another clean bottle. Add clear barium hydroxide 
solution until no further precipitate forms. Again allow to settle until clear. 
Draw off about 175 ce. and dilute to 10 liters with freshly boiled distilled water. 
Preserve in a stock bottle provided with a large guard tube filled with soda 
lime. Determine the exact strength by titrating against pure benzoic acid 
(C_H_COOH) using phenolphthalein as indicator. (See Bureau of Standards 
Scientific Paper No. 183.) This solution will be approximately N /4: but do not 
attempt to adjust it to any exact value. Determine its exact strength and 
make proper corrections in using it. 

Alcoholic Sodium Hydroxide Solution.—Dissolve pure NaOH in 95-per-cent 
ethyl alcohol in the proportion of about 22 g. per 1000 ce. Let stand in a stop- 


ee FGI 


Analysis of Paint Oils 441 
nn ea i Ee rl 


pered bottle. Decant the clear liquid into another bottle, and keep well stop- 
pered. This solution should be colorless or only slightly yellow when used; 
it will keep colorless longer if the alcohol is previously treated with NaOH 
(about 80 g. to 1000 ce.), kept at about 50° G for 15 days, and then distilled. 
For an alternate method see Journal, American Chemical Society, 1906, p. 395. 

Half Normal Sulfuric Acid Solution.—Add about 15 ce. HSOq (sp. gr. 1.84) 
to distilled water, cool and dilute to 1000 ce. Determine the exact strength 
by titrating against freshly standardized NaOH or by any other accurate 
method. Hither adjust to exactly N /2 strength or leave as originally made, 
applying appropriate correction. 


METHOps. 

5. The oil shall be tested in accordance with the following methods: 

General.—The laboratory sample shall be thoroughly mixed by shaking, 
stirring, or pouring from one vessel to another and the samples for the indi- 
vidual tests taken from this thoroughly mixed sample. 

Loss on Heating at 105 to 110° C.—Place 10 g. of the oil in an accurately 
weighed 200-cec. Erlenmeyer flask; weigh. Heat in an oven at a temperature 
between 105 and 110° C. for 30 minutes; cool and weigh. Qalculate the per- 
centage loss. This determination shall be made in a current of dry carbon 
dioxide gas. . 

Foots.—With all materials at a temperature between 20 and 27° C., mix, 
by shaking in a stoppered flask for exactly one minute, 25 cc. of the well- 
shaken sample of oil, 25 cc. of acetone and 10 cc. of the acid calcium chloride 
solution. Transfer the mixture to a burette where settling can take place for 
24 hours. The temperature during this period should be between 20 andreas ify 

The volume of the stratum lying between the clear calcium chloride solu- 
tion and the clear acetone and oil mixture is read in tenths of a cubic centi- 
meter or a fraction thereof. This reading multiplied by four expresses the 
amount of foots present as percentage by volume of the oil taken. 

Specific Gravity—Use a pyknometer accurately standardized and having 
a capacity of at least 25 cc., or any other equally accurate method, making the 
test at 15.5° C., water being 1 at 15.5° C. 

Acid Number.—Weigh from 5 to 10 g. of the oil. Transfer to a 300-ce. 
Erlenmeyer flask. Add 50 cc. of neutral 95-per-cent ethyl alcohol. Put a con- 
denser loop inside the neck of the flask. Heat on a steam bath for 30 minutes. 
Cool and add phenolphthalein indicator. Titrate to a faint permanent pink 
color with the standard solium hydroxide solution. Calculate the acid number 
(milligrams KOH per gram of oil). 

Saponification Number.—Weigh about 2 g. of the oil in a 300-cc. Erlen- 
meyer fiask. Add 25 ec. alcoholic sodium hydroxide solution. Put a condenser 
loop inside the neck of the flask and heat on the steam bath for one hour. 
Cool, add phenolphthalein as indicator, and titrate with N /2 H,SO4. Run 
two blanks with the alcoholic sodium hydroxide solution. These should check 
within 0.1 cc. N/2 H2SO,4. From the difference between the number of cubic 
centimeters of N/2 H.SO,4 required for the blank and for the determination, 
calculate the saponification number (milligrams KOH required for 1 g. of 
the oil). 

Unsaponifiable Matter—Weigh 8 to 10 g. of the oil. Transfer to a 250-ce. 
long-neck flask. Add 5 ce. of strong solution of sodium hydroxide (equal 
weights of NaOH and H,0), and 50 ce. 95-per-cent ethyl alcohol. Put a con- 


442 Analysis of Paint Oils 


ee —————————t 


denser loop inside the neck of the flask and boil for two hours. Occasionally 
agitate the flask to break up the liquid, but do not project the liquid onto the 
sides of the flask. At the end of two hours remove the condenser and allow 
the liquid to boil down to about 25 cc. 

Transfer to a 500-cc. glass-stoppered separatory funnel, rinsing with water. 
Dilute with water to 250 cc., add 100 cc. redistilled ether. Stopper and shake 
for one minute. Let stand until the two layers separate sharp and clear. Draw 
all but one or two drops of the aqueous layer into a second 500-ec. separatory 
funnel and repeat the process, using 60 cc. of ether. After thorough separation 
draw off the aqueous solution into a 400-cc. beaker, then the ether solution 
into the first separatory funnel, rinsing down with a little water. Return the 
aqueous solution to the second separatory funnel and shake out again with 
60 cc. of ether in a similar manner, finally drawing the aqueous solution into 
the beaker and rinsing the ether into the first separatory funnel. 

Shake the combined ether solution with the accumulated water rinsings and 
let the layers separate sharp and clear. Draw off the water and add it to 
the main aqueous solution. Shake the ether solution with two portions of 
water (about 25 ce. each). Add these to the main water solution. 

Swirl the separatory funnel so as to bring the last drops of water down to 
the stopcock, and draw off until the ether solution just fills the bore of the 
stopcock. Wipe out the stem of the separatory funnel with a bit of cotton 
on a wire. Draw the ether solution (portionwise if necessary) into a 250-ce. 
flask and distill off. While still hot, drain the flask into a small weighed 
beaker, rinsing with a little ether. Evaporate this ether, cool and weigh. 


Note.—The unsaponifiable oil from adulterated drying oils is volatile and 
will evaporate on long heating. Therefore heat the beaker on a warm plate, 
occasionally blowing out with a current of dry air. Discontinue heating as 
soon as the odor of ether is gone. 


Hanus Iodine Number.—Place a small quantity of the sample in a small 
weighing burette or beaker. Weigh accurately. Transfer by dropping about 
0.15 g. (0.10 to 0.20 g.) to a 500-cce. bottle having a well-ground glass stopper, 
or an Erlenmeyer flask having a specially flanged neck for the iodine test. 
Reweigh the burette or beaker and determine the amount of sample used. 
Add 10 ce. of chloroform. Whirl the bottle to dissolve the sample. Add 
10 cc. of chloroform to each of two empty bottles like that used for the sample. 
Add to each bottle 25 ce. of the Hanus solution and let stand with occasional 
shaking for one-half hour. Add 10 ce. of the 15-per-cent potassium iodide 
solution and 100 cc. of water, and titrate with standard sodium thiosulfate, 
using starch as indicator. The titrations on the two blank tests should agree 
within 0.1 ce. From the difference between the average of the blank titration 
and the titration on the samples and the iodine value of the thiosulfate solu- 
tion, calculate the iodine number of the samples tested. (Iodine number is 
centigrams of iodine to 1 g. of sample.) 

Color——Prepare a fresh solution of pure potassium bichromate in pure 
colorless H,SO,4 (sp. gr. 1.84). This solution should be in the proportion of 
1.0 g. potassium bichromate to 100 ce. (184.0 g.) H,SO,. Place the oi] and 
colored solution in separate thin-walled, clear glass tubes of the same diameter 
(1 to 2 cm.) to a depth of not less than 2.5 cm. and compare the depths of color 
by looking transversely through the columns of liquid by transmitted light. 


a 


Analysis of Paint Oils 443 


A. 8S. T. M. STANDARD SPECIFICATIONS FOR 


PERILLA OIL, RAW OR REFINED 


I. PROPERTIES AND TESTS. 
1. Perilla oil, raw or refined, shall conform to the following requirements: 


RICO GG rire stk sce cece sess ceensence 2.5 

Loss on heating at 105 to 110° C., per cent...... 0.2 at 
Meeeeuceeravity at 15.5° /15.5° C....... eee “rat 0.932 
NM Es yee Gio k pole vcvesecs'eoeeseeedes 5.0 ee 
em estION HUMPCL 2.2... ec cc tect ce acees “ae 190 
Sepmeriiper (HANUS)... 0... ccc tc wesc cece as 191 
Unsaponifiable matter, per cent................ Lb c. 
JO CEE eee Gicieke o-vity « oes. 0 5 


Not darker than a freshly 
prepared solution of 
1.0 g. potassium bichro- 
mate in 100 ce. pure 
H.SO,4 (sp. gr. 1.84). 


II. METHODS OF TESTING. 
SOLUTIONS REQUIRED. ; 

2. The following reagents will be required: 

Acetone that will pass the specifications of the United States Pharma- 
copoeia. 

Acid Calcium Chloride Solution.—Saturate with calcium chloride a mix- 
ture of 90 parts water and 10 parts HCl (sp. gr. 1.19). 

Standard Sodium Thiosulfate Solution.—Dissolve pure sodium thiosulfate 
in distilled water that has been well boiled to free it from carbon dioxide in 
the proportion so that 24.83 g. crystallized sodium thiosulfate will be present 
in 1000 ce. of the solution. It is best to let this solution stand for about two 
weeks before standardizing. Standardize with pure resublimed iodine. (See 
Treadwell-Hall, Analytical Chemistry, Vol. II, third edition, p. 646.) This 
solution will be approximately 0.1 N and it is best to leave it as it is after 
determining its exact iodine value, rather than to attempt to adjust it to 
exactly 0.1 N strength. Preserve in a stock bottle with a guard tube filled 
with soda lime. 

Starch Solution.—Stir up 2 to 3 g. of potato starch or 5 g. soluble starch 
with 100 ce. of 1-per-cent salicylic acid solution, add 800 to 400 ce. boiling 
water, and boil the mixture until the starch is practically dissolved. Dilute 
to 1 liter. 

Potassium Iodide Solution.—Dissolve 150 g. of potassium iodide free from 
iodate in distilled water and dilute to 1000 cc. 

Hanus Solution.—Dissolve 13.2 g. of iodine in 1000 ce. of glacial acetic acid 
(99.5-per-cent) that will not reduce chromic acid. Add enough bromine to 
double the halogen content, determined by titration (3 cc. of bromine is 
about the proper amount). The iodine may be dissolved by the aid of heat, 
but the solution should be cold when the bromine is added. 

Standard Sodium Hydroxide Solution—Prepare a stock concentrated 
solution of sodium hydroxide by dissolving NaOH in water in the proportion 
of 200 g. of NaOH to 200 ce. of water. Allow this solution to cool and settle 
in a stoppered bottle for several days. Decant the clear liquid from the 
precipitate of sodium carbonate into another clean bottle. Add clear barium 


444 Analysis of Paint Oils 


hydroxide solution until no further precipitate forms. Again allow to settle 


until clear. Draw off about 175 cc. and dilute to 10 liters with freshly boiled. 


distilled water. Preserve in a stock bottle provided with a large guard tube 
filled with soda lime. Determine the exact strength by titrating against pure 
benzoic acid (CgH; COOH) using phenolphthalein as indicator. (See Bureau 
of Standards Scientific Paper No. 183.) This solution will be approximately 
0.25 N, but do not attempt to adjust it to any exact value. Determine its 
exact strength and make proper corrections in using it. 

Alcoholic Sodium Hydroxide Solution—Dissolve pure NaOH in 95-per-cenr 
ethyl alcohol in the proportion of about 22 g. per 1000 ce. Let stand in a 
stoppered bottle. Decant the clear liquid into another bottle, and keep well 
stoppered. This solution should be colorless or only slightly yellow when 
used; it will keep colorless longer if the alcohol is previously treated with 
NaOH (about 80 g. to 1000 cc.), kept at about 50° C. for 15 days, and then 
distilled. For an alternate method see Journal, American Chemical Society, 
1906, p. 395. 

Half Normal Sulfuric Acid Solution—Add about 15 cc. HeSO, (sp. gr. 
1.84) to distilled water, cool and dilute to 1000 ec. Determine the exact 
strength by titrating against freshly standardized NaOH or by any other 
accurate method. Either adjust to exactly 0.5 N strength or leave as origi- 
nally made, applying appropriate correction, 


METHODS. 

2 The oil shall be tested in accordance with the following methods: 

General_—The laboratory sample shall be thoroughly mixed by shaking, 
stirring, or pouring from one vessel to another and the samples for the 
individual tests taken from this thoroughly mixed sample. 

Loss on Heating at 105 to 110° C.—Place 10 g. of the oil in an accurately 
weighed 200-cc. Erlenmeyer flask; weigh. Heat in an oven at a temperature 
between 105 and 110° C. for 30 minutes; cool and weigh. Calculate the per- 
centage loss. This determination shall be made in a current of dry carbon 
dioxide gas. 

Foots.—With all materials at a temperature between 20 and 27° C., mix, 
by shaking in a stoppered flask for exactly one minute, 25 cc. of the well- 
shaken sample of oil, 25 ec. of acetone and 10 ce. of the acid calcium chloride 
solution. Transfer the mixture to a burette where settling can take place 
for 24 hours. The temperature during this period should be between 20 and 
Pg eae &? 

The volume of the stratum lying between the clear calcium chloride solu- 
tion and the clear acetone and oil mixture is read in tenths of a cubic cen- 
timeter or a fraction thereof. This reading multiplied by four expresses the 
amount of foots present as percentage by volume of the oil taken. 

Specific Gravity—Use a pyknometer accurately standardized and haying 
a capacity of at least 25 cc., or any ier ee) accurate method, making 
the test at 15.5° C., water Haine 1 at 165° 6, 

Acid Number.-—Weigh from 5 to 10 g. of the oil. Transfer to a 300-ce. 
Erlenmeyer flask. Add 50 ce. of neutral 95-per-cent ethyi alcohol. Put a 
condenser loop inside the neck of the flask. Heat on a steam bath for 30 
minutes. Cool and add phenolphthalein indicator. Titrate to a faint per- 
manent pink color with the standard sodium hydroxide solution. Calculate 
the acid number (milligrams of KOH for 1 g. of the oil). 


ee ee ee ee eS 


Analysis of Paint Oils 445 


Saponification Number.—Weigh about 2 g. of the oil in a 300-ce. Erlen- 
meyer flask. Add 25 ce. of alcoholic sodium hydroxide solution. Put a con 
denser loop inside the neck of the flask and heat on the steam bath for one 
hour. Cool, add phenolphthalein as indicator, and titrate with 0.5 N H»)SOx4. 
Run two blanks with the alcoholic sodium hydroxide solution. These should 
check within 0.1 cc. of 0.56 N H.SO4. From the difference between the num- 
ber of cubic centimeters of 0.5 N HoSO,4 required for the blank and for the 
determination, calculate the saponification number (milligrams of KOH 
required for 1 g. of the oil). : 

Unsaponifiable Matter—Weigh 8 to 10 g. of the oil. Transfer to a 250-ce. 
long-neck flask. Add 5 ce. of strong solution of sodium hydroxide (equal 
weights of NaOH and H,O), and 50 cc. of 95-per-cent ethyl alcohol. Put a 
condenser loop inside the neck of the flask and boil for two hours. Occa- 
sionally agitate the flask to break up the liquid but do not project the liquid 
onto the sides of the flask. At the end of two hours remove the condenser and 
allow the liquid to boil down to about 25 ce. 

Transfer to a 500-cc. glass-stoppered separatory funnel, rinsing with water. 
Dilute with water to 250 cc., add 100 cc. of redistilled ether. Stopper and 
shake for one minute. Let stand until the two layers separate sharp and 
clear. Draw all but one or two drops of the aqueous layer into a second 
500-ce. separatory funnel and repeat the process using 60 cc. of ether. After 
thorough separation draw off the aqueous solution into a 400-cc. beaker, 
then the ether solution into the first separatory funnel, rinsing down with a 
little water. Return the aqueous solution to the second separatory funnel and 
shake out again with 60 cc. of ether in a similar manner, finally drawing the 
aqueous solution into the beaker and rinsing the ether into the first separa- 
tory funnel. 

Shake the combined ether solution with the accumulated water rinsings 
and let the layers separate sharp and clear. Draw off the water and add it 
to the main aqueous solution. Shake the ether solution with two portions of 
water (about 25 cc. each). Add these to the main water solution. 

Swirl the separatory funnel so as to bring the last drops of water down 
to the stopcock, and draw off until the ether solution just fills the bore of the 
stopcock. Wipe out the stem of the separatory funnel with a bit of cotton 
on a wire. Draw the ether solution (portionwise if necessary) into a 250-cc. 
- flask and distill off. While still hot, drain the flask into a small weighed 
beaker, rinsing with a little ether. Evaporate this ether, cool and weigh. 


Note.—The unsaponifiable oil from adulterated drying oils is volatile and 
will evaporate on long heating. Therefore heat the beaker on a warm plate, 
occasionally blowing out with a current of dry air. Discontinue heating as 
soon as the odor of ether is gone. 


Hanus Iodine Number.—Place a small quantity of the sample in a small 
weighing burette or beaker. Weigh accurately. Transfer by dropping about 
0.15 g. (0.10 to 0.20 g.) to a 500-ce. bottle having a well-ground glass stopper, 
or an Erlenmeyer flask having a specially flanged neck for the iodine test. 
Reweigh the burette or beaker and determine the amount of sample used. 
Add 10 ce. of chloroform. Whirl the bottle to dissolve the sample. Add 10 
ec. of chloroform to each of two empty bottles like that used for the sample. 
Add to each bottle 25 cc. of the Hanus solution and let stand with occasional 
shaking for 30 minutes. Add 10 ce. of the 15-per-cent potassium iodide solu- 


446 Analysis of Paint Oils 


ae 


tion and 100 ec. of water, and titrate with standard sodium thiosulfate using 
starch as indicator. The titrations on the two blank tests should agree within 
0.1 ec. From the difference between the average of the blank titration and 
the titration on the samples and the iodine value of the thiosulfate solution, 
caleulate the iodine number of the samples tested. (lodine number is centi- 
grams of iodine to 1 g. of sample.) 

Color.—Prepare a fresh solution of pure potassium bichromate in puré 
colorless HySO,4 (sp. gr. 1.84). This solution should be in the proportion of 
1.0 g. of potassium bichromate to 100 cc. (184.0 g.) of H.SO4. Place the oil 
and colored solution in separate thin-walled, clear glass tubes of the same 
diameter (1 to 2 cm.) to a depth of not less than 2.5 cm. and compare the 
depths of color by looking transversely through the columns of liquid by 
transmitted light. 


CHAPTER XXIV 


ANALYSIS OF VARNISH 


The testing of oleo-resinous varnish should largely be of a 
physical nature. Such properties as odor, consistency, clarity, 
flowing, time of drying, character of finish, hardness, resist- 
ance to moisture and abrasion, elasticity, etc., point out the 
real value of a varnish. Chemical tests that give additional 
information, sometimes of value, are as follows: Acid num- 
ber, ash, character of solvent, fixed oil and resins. 


Acid Number.—Ten to 20 grams of the varnish are weighed 
in a small Erlenmeyer flask, 50 ce. neutral aleohol added, and 
a small funnel inserted in the neck. Heat on the water bath 


—————— 


. = ee 3 
WW 


FIGURE 179 


Apparatus for determining gas resistance of varnish. See Federal Specifi- 
cations Board Specifications, back of volume. 


448 Anal ysis of Varnish 


for one-half hour, with occasional shaking. Allow to cool 
somewhat, add two drops of phenolphthalein indicator and 
titrate with tenth-normal potassium hydroxide solution. The 
acid number is the number of milligrams of KOH required to 
neutralize each gram of the varnish. Use of a mixture of 
equal volumes of alcohol and benzol 90° gives the true acid 
number of a varnish including colloidal acidity that would not 
be indicated by alcohol alone. (See page 465.) 


Ash-—Weigh in a porcelain or fused silicia crucible several 
grams of the varnish. Burn off over a small Bunsen flame, 
using great caution to avoid boiling over and spattering. 
When at combustible matter is destroyed, weigh the ash and if 
desired analyze it. 


Solvent.—Steam distillation of a portion of the varnish will 
remove the solvents, leaving a residue of fixed oils and varnish 
resins, which may be weighed after driving off the water. The 
distillate should be examined as recommended under Turpen- 


FIGURE 180 


Apparatus for determining draft resistance of varnish. See Federal Specifi- 
cations Board Specifications, back of volume. 


tine Specifications. The amount of mineral spirits and turpen- 
tine may thus be determined. 


It is customary to conduct the steam distillation upon 90 
grams of varnish in a 500-ce. Erlenmeyer flask placed in an oil 
bath maintained at about 130° F. The distillate may be col- 
lected in a separatory funnel. The water may then be drawn 
off and the distillate examined. 


A much more rapid and fully as accurate a method for de- 
termining the percentage of volatile is as follows. This 
method, however, does not yield the actual volatile for subse- 
quent examination. 2 


Analysis of Varnish 449 


Percentage of Volatile-—Place a portion of the sample in a 
stoppered bottle. Weigh the container and sample. Transfer 
about 1.5 grams of the sample to a flat bottom metal dish about 
8 cm. in diameter (a friction top can plug). Weigh the bottle 
again and by difference calculate the exact weight of the por- 
tion of the sample transferred to the metal dish. Heat the 
dish and contents in an oven maintained at 105° to 110° C. for 3 
hours. Cool and weigh. From the weight of the residue left 
in the dish and the weight of the sample taken, calculate the 
percentage of non-volatile residue. 


Fixed Oils and Resins.—In the above determination, the 
total amount of fixed oils and resins is obtained. It is a diffi- 
cult matter, however, to determine the exact percentage and 
character of resins that have been used in the manufacture 
of the varnish. This is due to the fact that during the process 
of heating oils in the presence of resins many intricate chem- 
ical changes are brought about, a considerable portion of the 
resins being distilled off in the form of vapors and combina- 
tions of the oil brought about that are difficult of separation. 
One of the best methods, however, of separating the fixed oils 
and varnish resins is carried out in the following manner: 


A portion of about a half ounce of the varnish resin should 
be placed in a 300-ce. tared beaker. There should then be 
added about 200 ce. of ice-cold petroleum ether. After stir- 
ring the beaker should be covered and allowed to stand, prefer- 
ably in a dish containing ice. In an hour’s time the resinous 
ingredients will be found precipitated at the bottom of the 
beaker or adhering to the side thereof (with the exception of 
rosin, which is largely soluble in petroleum ether). The pre- 
cipitated resins should be washed with fresh portions of cold 
petroleum ether two or three times, pouring the decanted por- 
tions into a large bottle. The combined portions of petroleum 
ether may then be filtered through a tared filter, adding by the 
aid of a stirring rod the resins contained in the beaker. The 
filter paper and the beaker with the resins may then be dried 
at 100° C. and weighed. The combined filtrates may be dis- 
tilled to obtain the fixed oil as a residue, which may be ex- 
amined for constants. (This fixed oil may contain rosin.) 
The amount of rosin contained in a varnish may be roughly 
ascertained by thoroughly shaking in a separatory funnel a 
portion of the varnish with a large quantity of absolute alco- 


450 Analysis of Varnish 


hol. The rosin may be obtained by evaporation of the alco- 
holic extracts. The fixed oils after oxidation or polymeriza- 
tion, as caused by the heating of the varnish during manufac- 
ture, are not readily soluble in alcohol. 


Separation of Polymerized Oils and Resins.—In the making 
of varnish, most oils become oxidized or polymerized to a con- 
dition resembling resins. For instance, when a varnish is ex- 
amined for resins by the above method, it will often be found 
that a considerable amount of matter insoluble in pertroleum 
ether will be obtained even when hard resins are absent. The 
insoluble substance is oxidized or polymerized oil. It may be 
differentiated from varnish resins by the fact that it may be 
saponified by alcoholic potash. | 


This method, as used by the regulatory division of the State 
of North Dakota, is the original method published by HE. W. 
Boughton of the Bureau of Standards (see U.S. Bureau of 
Standards Technologic Bulletin 65), as modified in North Da- 
kota. Although it involves a tremendous amount of work, it is 
probably the most accurate method for the separation of 
polymerized oils and resins. The method follows Boughton’s 
original scheme very closely. The use, however, of ice-cold 
ether and ice-cold water is probably an advantage in that the 
ether separations are quicker and sharper. In Boughton’s orig- 
inal method, the material extracted by ether from the first 
saponification mixture of acids and fatty acid soaps 1s termed 
unsaponifiable matter. In the North Dakota revision, the pro- 
posal is made to add this same ether extract to the resin por- 
tion. This constitutes a somewhat radical difference between 
the two schemes and clearly brings out the fact that neither 
Boughton’s method nor the North Dakota method can be relied 
upon to give the true oil content of present-day varnishes. For 
instance, at least one of the varnishes on the. market today 
contains wool fat (degras). In Boughton’s method this 
product would show up as unsaponifiable matter, while im the 
North Dakota method the unsaponifiable part of the wool fat 
would be included in the resins. This same difference would 
be true of a varnish containing paraffin. On the other hand, 
a varnish made of tung oil and cumarin resin would show a 
high unsaponifiable and resin content by Boughton’s method, 
while the North Dakota method would indicate the cumarin as 
resin. 3 


Analysis of Varnish 451 


In view of the above, it is quite apparent that neither one of 
these methods should be included as a part of any routine 
method of analysis of a varnish but should be merely classed 
as “‘stunt’’ tests for a research laboratory, where an insight 
into the ingredients of a varnish is desired. All of which 
brings out the absolute futility of a varnish analysis as a basis 
of evaluation. Physical tests afford the only reliable data in 
judging the properties of an oleo-resinous varnish. 


Method.—Weigh by difference from 4 to 6 grams of the 
varnish into a 125-cc. Erlenmeyer flask, add 25 ce. of water and 
boil gently until not over 5 ce. of water is left. This is best 
performed by placing the flask in an oil bath, and by passing a 
stream of carbon dioxide through the mixture during the evap- 

oration. Then add 25 ce. each of half normal alcoholic potash 
and benzol, and reflux for one hour. 

Evaporate the solution down to about 10 ce. and transfer to 
a 900-ec. globe-shaped separatory funnel, rinsing the flask well 
with water, alcohol and ether. Add 100 cc. each of water and 
ethyl ether and shake well, using a moderate circular motion. 
In this and all similar operations use ice-cold ether and ice- 
cold water. The shaking should be repeated three times. 
Should an emulsion ‘eank and not break within five minutes, 
add 2 ce. of alcohol. 


Draw off the aqueous layer into another separatory funnel 
and wash the ether layer twice with cold water. Add the wash- 
ings to the aqueous layer and transfer the ether layer to a 
weighed Erlenmeyer flask labeled ‘‘Gums.’’ Acidify the aque- 
ous layer and completely extract with ether. Transfer the 
ether solution to the Erlenmeyer flask into which the varnish 
was weighed and distill off the solvent, using a vertical con- 
denser. Then add 10 ce. absolute alcohol and evaporate on a 
steam bath. This is to remove the water present. Distill off 
the solvent in the ‘‘Gums’’ flask whenever the flask becomes 
half-full. All ether solutions of unsaponifiable matters and 
the resins acids that are separated out from subsequent ex- 
tractions are transferred to this flask. 


To the residue extracted from the acid solution add 20 ee. 
of absolute alcohol and 20 ce. of a mixture of 4 parts of 
absolute alcohol and 1 part of concentrated sulphuric acid. 
Reflux for five minutes, transfer to a separatory funnel, rins- 
ing the flask with meter and ether, add 100 ee. of amen 


452 Analysis of Varnish 

Shake well, add 100 cc. of a 10-per-cent solution of sodium 
chloride, and shake several times. Draw off the aqueous 
layer and extract with 50 ce. of ether. Wash the combined 
ether layer and discard the aqueous layers. ‘To the ether 
layer add 50 ce. fifth normal aqueous potassium hydroxide 
and 10 ec. of aleohol and shake well, using a moderate circu- 
lar motion. Repeat the shaking as soon as the layers have 
separated. Separate the layers and wash the ether layer with 
50 ec. of water containing 5 ec. of the aqueous potassium 
hydroxide and 5 ce. of alcohol. 


Combine the aqueuos layers and extract with ether keep- 
ing all insoluble soaps with the ether layer. Then combine 
the ether layers, transfer to an Erlenmeyer flask, and distill 
off the solvent. Take the aqueous layers, acidify with hydro- 
chloric acid and extract completely with ether. Transfer this 
ether solution to the ‘‘Gums”’ flask. ‘ 


Take the residue and reflux with 25 ec. of alcoholic potash 
for one hour. Evaporate on steam bath until only 10 ce. re- 
mains. Cool, transfer to a separatory funnel with the aid 
of 50 ec. each water and ether and shake. Use the same 
moderate circular motion. Repeat the shaking twice and 
draw off the aqueous layer. Extract the aqueous layer with 
ether again. Combine the ether layers and wash twice with 
600 ec. portions of water. Transfer the ether layers to the 
‘‘Gums’’ flask. Take the aqueous layer and the washings 
from the ether layer, acidify with hydrochloric acid and ex- 
tract completely with ether. Transfer these ether extracts to 
a weighed Erlenmeyer flask, distill off the solvent and heat 
on a steam bath with small portions of absolute alcohol until 
all of the water is removed. Then heat to constant weight 
at 105° C., in an oven filled with carbon dioxide. Weigh as 
fatty acids. 


Take the ‘‘Gums”’ flask, distill off the solvent, remove the 
water, dry and weigh as in the case of the fatty acids. This 
weight is reported as resins or as varnish gums. 


Calculations: 


Wt. of Resins < 1.07 
(a) ———__—_ 


< 100 = percent total of resins (direct). 
Wt. of sample 


Analysis of Varnish 453 


Wt. of fatty acids 
ee —— < 100 — per cent of total oils. 
Wt of sample 


(c) (Per cent of non-volatile—per cent of ash) = per cent of total resins 
(by difference). 


A method of examining the fatty acids separated from the 
resins in a varnish, as described by de Waele* and by Wolff,+ 
is referred to on page 329 of the very valuable book entitled 
‘Varnishes and Their Components,’’ by R. S. Morrell (Ox- 
ford Technical Publications). The reader is referred to the 
original papers for a detailed study of the methods. It is 
beheved that while occasion may arise for work of this char- 
acter, as a rule much more information regarding the suit- 
ability of a varnish for a certain purpose can be obtained 
by practical physical tests, as referred to in other sections 
of this volume. P 


Tung Oil Detection.—F or ascertaining the presence of tung 
oil in the non-volatile portion of a varnish, see test on page 694. 


EXAMINATION OF Sprrit VARNISHES 


Distillation of 100 ec. may be made when it is important to 
determine the type of solvents used. The distillate can be 
fractioned and tested for alcohol, benzol, or similar light sol- 
vents generally employed in such varnishes. Mineral spirits 
and turpentine are to be looked for when spirit varnishes of 
the dammar type are believed present. The solvents used 
in shellac varnish and shellac varnish substitutes, Manilla, 
Rosin, ete., are generally of the alcohol soluble type. 

For a determination of the amount of solvent present in a 
spirit varnish, a quantity can be weighed out in a friction top 
tin cover, evaporated in an oven, and the residue weighed as 
described elsewhere in this volume for the determination of 
the amount volatile matter in varnishes. The residue left 
from the evaporation may be examined to secure some in- 
formation regarding the type of resin used. Determination 
of the solubility of the residue in various solvents, determina- 
tion of the acid value, and similar characteristics, as out- 


*de Waele, Journ. Oil Col. Chem. Assoc., 1920, a Kat iy 
1H. Wolff, Chem. Age, 1921, 15, 2989. 


454 Analysis of Varnish 


——— 


lined under the chapter for the examination of resin, may 
afford considerable information. 


Morrell, in commenting upon a scheme for the detection 
and separation of common resins, as published by H. Rebs 
in ‘‘Die Spirituslackfabrikation’’ (1905), makes the follow- 
ing statement: | 


‘‘Concentrated acetic acid will dissolve lac, rosin, an oleo- 
resin of turpentine and accroides resin. Very dilute ammonium 
chloride will dissolve lac, while manila, sandarach, rosin, 
and accroides are insoluble. Benzine (light petroleum) will 
dissolve rosin or an oleoresin, but manila, sandarach, lac, 
and accroides are insoluble in that solvent. In order to 
separate the different resins qualitatively and quantitatively 
in a spirit varnish, the solvent is distilled off, the residue 
is finely powdered and warmed on the water bath with the 
solvents mentioned above. If lac and rosin be present, the 
lac will dissolve in very dilute ammonium chloride. Lac 
may be separated from manila or sandarach, and likewise 
from rosin, but the separation of sandarach from manila 
copal is very doubtful. The estimation of dammar admixed 
with spirit copal or kauri by means of alcohol and chloro- 
form has been put forward by Stewart.* ‘The resin is boiled 
with alcohol, which dissolves the spirit copal and part of the 
dammar. The residue is extracted with chloroform in a Soxh- 
let, whereby the remainder of the dammar is dissolved. The 
amount of the chloroform-soluble extract is a measure of the 
percentage of dammar. The insolubility of a genuine sam- 
ple of the particular variety of dammar must be known. 

‘‘Tt is evident that the methods of separation of the indi- 
vidual resins in a mixture are by no means satisfactory, and 
there is need for much investigation in that field.j At pres- 
ent the works tests are essentially the most reliable. Elastic- 
ity, lustre, hardness, uniformity of film, and, in the case 


of coloured spirit varnishes, stability to heat and light, are 


compared against special requirements. On metals the var- 
nish film must be clean and the coating must not have an acid- 
ity likely to set up chemical interaction with the metals. De- 
termination of acidity, behaviour on drying, flow, colour, and 


specific gravity are compared with corresponding values of. 


the standard sample. 


*S. Stewart, Journ. Soc. Chem. Ind., 1909, 28, 348. 
+ Dietrich, Analysis of Resins, 2nd Ed. 


ee ee ee ee ee | 


Analysis of Varnish 455 


“Tf the spirit varnish contain nitrocellulose celluloid, or 
cellulose acetate, the residue after the removal of the sol- 
vents must be examined by special tests. Treatment with 
a dilute solution of diphenylamine in concentrated sulphuric 
acid Will give a blue coloration in the presence of nitrocellulose. 
Nitrocellulose may be estimated in the residue by measuring 
the volume of nitric oxide evolved by the action of ferrous 
chloride and hydrochloric acid at 100° C., whereby the nitro- 
group of the nitrocellulose is reduced to nitric oxide. 


‘‘Celluloid may be detected by the identification of the 
incorporated camphor, which can be removed by ether or by 
methyl alcohol, in which the nitrocellulose is insoluble. 


‘‘Hor the detection of cellulose acetate, gentle heating with 
concentrated sulphuric acid and a little alcohol will give 
amyl acetate. 


‘‘Mor the identification of the cellulose componént original 
residue may be boiled with hydrochloric acid (sg. 1.10), 
neutralised, and tested for the sugars with TFehling’s 
solution. The cellulose in nitrocellulose and celluloid can 
likewise be detected by the production of reducing sugars on 
hydrolysis.’’—For methods of testing shellac varnishes see 
Chapter X XIX. 


A. 8. T. M. STANDARD METHODS OF TESTING | 
OLEO-RESINOUS VARNISHES 


1. (a) All tests shall be made at room temperature between 21 and 
32° ©. (70 and 90° F.). 

(b) All tests shall be made in diffused light (not in direct sunlight). 

(c) When a can of varnish has been opened and part of its contents has 
been used, the remainder shall immediately be placed in air-tight containers 
which the varnish entirely fills, leaving not more than 2 per cent of .air 
space. ies 
(d) The tin panels used shall be cut from bright tinplate weighing not 
more than 25 g. nor less than 19 g. per square decimeter (0.51 to 0.39 Ib. 
per sq.ft. ). 


NoTE.—Commercial No. 31 gage bright tinplate should weigh about 0.44 
lb. per sq. ft. 


It is important that the tinplate shall be within the limits prescribed. 
The panel shall be about 7.5 by 13 em. (3 by 5 in.) and shall be thoroughly 
cleaned with benzol immediately before using. 


Norte.—It is important that the rags used in wiping the panels are clean. 


456 Analysis of Varnish 


Ee 


I. APPEARANCE 
29. Some of the thoroughly mixed sample shall be poured into a clear 
glass bottle or test tube, 1.5 to 2.0 em. (% to 134, in.) in diameter to a depth 
of at least 2.5 em. The varnish shall then be examined by transmitted light 
and shall be clear and transparent. 


II. COLOR 

3. (a) Standard color solutions shall be prepared by dissolving 1, 2, 3, 
4, 5 and 6 g., respectively, of pure powdered potassium bichromate in 100 ce. 
of pure concentrated HjSO4 (sp. gr. 1.84). Gentle heat may be applied, if 
necessary, to effect the solution of bichromate. 

(b) The standard color solutions and a sample of the varnish to be tested 
shall be poured into thin-walled glass tubes 1.5 to 2.0 em. (5% to 1%. in.) in 
diameter to a depth of at least 2.5 em. The color comparison shall be made by 
placing the tubes close together and looking through them by transmitted light. 

Since the potassium bichromate-sulfurie acid solution must be freshly 
made for this color comparison, it is frequently more convenient to compare 
samples with a series of permanently sealed tubes of varnish which have 
been previously found to be lighter in color than the standard solutions. When 
a sample is found to be darker than a standard tube of varnish, the bichromate 
standard should be made up for final decision. The color of the varnish shall 
be stated in terms of the standard (calling the standards No. 1, No. 2, No. 3, 
ete.) with which it is equal or lighter than. 


Nore.—Stabilized caramel solutions or other permanent colored liquids 
may be used as secondary standards. 


III. NON-VOLATILE MATTER 


4. A portion of the sample of the varnish shall be poured into a stoppered 
bottle or weighing pipette and weighed. About 1.5 g. of the sample shall be 
transferred to a flat-bottomed metal dish about 8 cm. in diameter. (Note.— 
A friction-top can plug is satisfactory.) The container shall be weighed again, 
and the exact weight of the portion of the sample transferred to the weighed 
dish shall be calculated by difference. The dish with its contents shall be 
heated for 3 hours in an oven maintained at 105 to 110° C. (221 to 230° F.). 
It shall then be weighed after cooling. 

5. The ratio of the weight of the residue to that of the sample, expressed 
as a percentage, shall be taken as the percentage of non-volatile matter in the 
varnish. 


IV. TEST FOR ELASTICITY OR TOUGHNESS 


6. The elasticity or toughness of the varnish shall be determined by pro- 
portionately reducing its elasticity or toughness by the addition of a standard 
solution of Rum Kauri gum in pure spirits of turpentine. 

7. (a) A distillation flask, water-cooled condenser and a tared receiver 
shall be arranged on a balance. Clear, bright, hard pieces of Kauri gum 
broken to the size of a pea shall be placed in the flask to about one-third its 
eapacity. The gum shall be carefully melted and distilled until 25 per cent 
by weight is collected in the tared receiver. At the end of the distillation the 
thermometer in the distillation flask with the bulb at the level of the dis- 


a, aoe 


wor ee te 


we Teen 


ve... 


Analysis of Varnish 457 


charging end of the flask should register about 316° C. (600° F.). The residue 
shall be poured into a clean pan and when cold it shall be broken into small 


pieces. 

(b) Standard Run Kauri Solution.—A quantity of the small broken pieces 
of Run Kauri, together with twice its weight of freshly re-distilled spirits of 
turpentine, using only that portion distilling between 153 and 170° CC. (308 
and 338° F.), shall be placed in a carefully tared beaker and dissolved by 
heating to a temperature of about 149° C. (300° F.). It shall then be brought 
to correct weight when cooled by the adition of the amount of re-distilled 
spirits of turpentine necessary to replace the loss by evaporation during the 
dissolving of the gum. 

8. (a) Having carefully determined the non-volatile content of the 
varnish in accordance with Section 4, 100 parts of the varnish by weight shall 
be taken and to it shall be added an amount of the standard Run Kauri 
solution equivalent to 50 per cent by weight of the non-volatile matter in the 
varnish and mixed thoroughly. 


Note.—The 50-per-cent standard Run Kauri reduction is given to illustrate 
the method. Any other percentage of standard Run Kauri reduction may be 
used, depending on what is required of the particular sample being tested. 


(vb) The varnish shall be flowed upon one of the tin panels described in 
Section 1 (d) and the panel be permitted to stand in a nearly vertical position 
at room temperature for nearly one hour. The panel shall then be placed 
in a horizontal position in a properly ventilated oven and baked for five hours 
at from 95 to 100° C. The panels shall then be removed from the oven and 
permitted to cool at room temperature (preferably 24° C. (75° F.)) for 15 
minutes. | 

9. The panel shall be placed with the varnished side uppermost over a 
3 mm. (1-in.) rod, held firmly by suitable supports, at a point equi-distant 
from the top and bottom edges of the panel and bent double rapidly. The 
varnish shall show no cracking whatsoever at the point of bending. For accu- 
rate results the bending of the panel should always be done at 24° C. (75° F.) 
for a lowering of the temperature will lower the percentage of reduction that 
the varnish will withstand without cracking, while an increase in tempertaure 
increases the percentage of reduction that the varnish will withstand. 

10. Varnishes which do not show cracks under this test shall be reported 
as passing a fifty-per-cent reduction while those that do crack shall be reported 
as not passing a fifty-per-cent reduction. 

The varnishes which have not cracked shall be tested again, changing the 
amount of reduction to sixty per cent, and, if they pass this amount of reduc- 
tion, they shall be reduced to seventy per cent. 

In a similar manner, varnishes which have cracked at fifty per cent shall 
be tested, using reductions of thirty and forty per cent. 

In this way the limits shall be determined within ten per cent at which a 
varnish passes one amount of reduction and does not pass the next. For 
example, varnishes may be reported as passing forty per cent, and breaking 
at fifty per cent. 


NotE.—It is suggested that a 20-g sample of varnish shall be sufficient for 
each reduction. If the non-volatile content of the varnish should be 48.6 per 
cent, then 4.86 g. of standard Run Kauri solution should be added to the 20 g. 
of varnish and a fifty-per-cent reduction will be obtained. 


458 Analysis of Varnish 


eT 


FLASH POINT 
The flash point shall be determined in accordance with the Standard Method 
of Test for Flash Point of Volatile Flammable Liquids (Serial Designation: 
D 56) of the American Society for Testing Materials. 


VISCOSITY 
Viscosity shall be determined by comparison at 25° C. (77° F.) with 
secondary standards whose viscosity expressed in poises has been accurately 
determined at that temperature. 
Notr.—Gardner-Holdt tubes may be used. See Circular No. 178, Scientific 
Section, Paint Manufacturers’ Association of the U. S. 


WATER TEST 
The varnish shall be poured on one of the standard tin panels and allowed 
to drain in a nearly vertical position and dry for 48 hours. The panel shall 
be placed in a beaker containing about 7 cm. (2.5 in.) of distilled water at 
room temperature (immersing the end of the panel which was uppermost 
during the drying) and left in water for 18 hours. The panel shall then be 
removed from the water, wiped carefully, and allowed to dry out at room 
temperature. The time required for whitening, if any, to disappear, shall be 
noted. The results of the water test shall be reported as follow: 
(1) Not visibly affected. 
(2) Whitening disappears within 20 minutes. 
(3) Whitening does not disappear in 20 minutes, but does disappear 
within 2 hours. 
(4) Whitening does not disappear within 2 hours, but does disappear 
within 24 hours. 
(5) Whitening does not disappear within 24 hours. 
Blooming, which sometimes occurs on immersion, is considered as a degree 
of whitening, 


A. 8S. T. M. TENTATIVE METHODS OF TESTING 
INSULATING VARNISH 

1. These tests are intended for varnishes which are applied by brushing, 
dipping or spraying, and are primarily for the purpose of providing electrical 
insulation. 

I. SPECIFIC GRAVITY. 

2. The specific gravity shall be measured with a pyknometer, Westphal 
balance or with a hydrometer so graduated that the specific gravity can be 
determined to 0.001. The temperature of the varnish shall be not less than 18° 
C. (64.4° F) nor more than 22° C. (71.6° F.) and corrected to 20° C. (68° F.) 
by applying a correction of 0.0007 per 1° C. (0.0004 per 1° F.). 


II. VISCOSITY. 
3. The viscosity shall be determined at 20° C. (68° F.) and the results 
shall be stated in terms of absolute viscosity—poise* or centipoise (centi- 
poise — 0.01 poise). 


*The absolute viscosity of a material or its viscosity in absolute units 
(c.g.s., poises) has been defined as the force in dynes required to move, at a 
velocity of 1 cm. per second, one surface having an area of 1 sq. cm. past 
another parallel like surface 1 cm. away, overcoming the resistance to shear 
of the material filling the space between. 


Analysis of Varnish 459 


Nore 1.—When measurements are made by an indirect method, the instru- 
ment used must be standardized. Oils of standard viscosity for use in stand- 
ardizing such instruments can be obtained from the U. S. Bureau of Standards. 


Note 2.—A description of the MacMichael viscosimeter as remodeled and 
improved for varnish testing may be obtained from the secretary of Committee 
D-9 together with directions for its calibration in absolute units. 


III. FLASH POINT. 
4. The flash point shall be determined in accordance with the Standard 
Method of Test for Flash Point of Volatile Flammable Liquids (Serial Desig- 
nation: D 56) of the American Society-for Testing Materials.* 


IV. TIME OF DRYING. 


5. (a) Specimens for this test shall be pieces of thoroughly cleaned, smooth 
sheet copper or brass about 3 cm. (1.18 in.) wide and 20 cm. (7.88 in.) long 
and about 0.127 mm. (0.005 in.) thick. 

(b) The specimen shall be dipped once in the varnish at a room tempera- 
ture of approximately 20° C. (68° F.) and withdrawn slowly and uniformly 
(about 38 em. (15 in.) per minute). The consistency of the varnish shall be 
first so adjusted by trial that, when dry as determined in accordance with Sec- 
tion 7, the thicknes of the film of varnish on each side of the metal shall be 
between 0.022 mm. (0.0009 in.) and 0.026 mm. (0.001 in.). Care shall be taken 
before dipping the specimens that the varnish has stood in the dipping tank 
for a sufficient length of time to be free from air bubbles. 

6. (a) Specimens of air-drying varnish shall be dried in dust-free air at 
a room temperature of approximately 20° C. (68° F.). 

(b) In the case of baking varnishes, six specimens shall be dipped and 
allowed to drain at a room temperature of approximately 20° C. (68° F.) until 
the varnish is set as indicated when the impression left on the surface by 
pressing lightly thereon with a finger will not become obliterated by further 
flow of the material. They are then to be dried in dust-free air in an oven 
at 105 to 110° G. (221 to 230° F.). At the end of the first 30 minutes, and 
again at the end of each 10-minute period thereafter, one specimen shall be 
taken from the oven and examined. In the case of slow-drying varnishes, 
this 10-minute period may be lengthened at the discretion of the operator. 

7. The varnish shall be considered dry when a specimen will not stick to 
itself when folded and pressed together between the thumb and finger at a 
temperature of approximately 20° C. (68° F.). 


V. DIELECTRIC STRENGTH TEST. 

8. (a) Specimens for the dielectric strength test shall be prepared by 
dipping pieces of kraft paper about 20 cm. (7.88 in.) square and about 0.076 
mm. (0.003 in.) thick into the varnish which shall be at the consistency pre- 
seribed in Section 5 (6). 


Note.—The paper used shall be that which is commercially known as No. 1 
Sulfate Kraft. The surface of the paper shall be smooth, free from pimples 
or lumps and reasonably free from hairy fibers. The paper shall also be free 
fishy conducting particles, slime spots, creases, cuts, specks or other “paper 

efects.” 


*1924 Book of A.S.T.M. Standards. 


460 Analysis of Varnish 


(b) Hach specimen shall be dipped twice, as specified in Section 5 (5b), 
once in each direction, in order to give a more uniform thickness of coating. 
The specimen shall be dried after each dip in the same vertical position in 
which it was dipped. 

(c) Specimens of air-drying varnish shall be dried in dust-free air after 
each dip at a room temperature of approximately 20° C. (68° F.) for a period 
600 per cent longer than that determined in accordance with Section 7, pro- 
vided such period does not exceed 24 hours. 

(d) Specimens of baking varnish shall be drained and then baked in dust- 
free air after each dip for a period 300 per cent greater than that determine: 
in accordance with Section 7, provided such period does not exceed 24 hours. 

(e) The final thickness of the specimen shall be 0.152 mm. (0.006 in.) to 
within + 15 per cent. 

9 (a) The dielectric strength of the specimen shall be determined by 
applying alternating potential to two circular metal disks, 5.08 cm. (2.0 in.) 
in diameter and with edges rounded to a radius of 0.64 em. (0.25 in.) which 
are placed in contact with the two sides of the specimen directly opposite 

each other and under a pressure of approximately 0.5 kg. (1.1 Ib.). Starting 

at zero, the voltage shall be increased uniformly to breakdown at a rate of 0.5 
kilovolt per second, except that if breakdown occurs at this rate in less than 
40 seconds, the rate shall be decreased so that breakdown will occur in not 
less than 40 seconds. If the material fails at less than 5 kilovolts, the mini- 
mum time shall be reduced from 40 seconds to 20 seconds. Ten such punc- 
tures are to be made at various points selected at random on each specimen. 
In each test the thickness of the specimen is to be determined as close to the 
point of puncture as practicable. 


Normr.—When necessary, in order to get ten punctures, additional specimens 
should be tested. 


(b) The frequency of the test potential shall be not greater than 100 cycles 
per second, and each part of the testing apparatus shall have a continuous 
rating of not less than 2 kva. (preferably larger). The wave form shall be a 
sine curve as defined, and the voltage shall be measured by methods approved 
by the American Institute of Electrical Engineers.* 

(c) The voltage may be controlled by any approved method which does 
not distort the wave form beyond the limits prescribed above and which does 
not subdivide the voltage in steps greater than 500 volts. The apparatus 
shall comply with the Standards of the American Institute of Electrical 
Engineers. 

10. The volts at puncture, the thickness of the specimen and the volts per 
mil of thickness shall be reported for each of the ten tests, together with the 
average, maximum and minimum volts per mil. 


Norr.—This test is relative only, but it gives more uniform results than » 


those obtained with a copper base. See the Appendix for a procedure for 
determining the dielectric strength on a copper base. 


VI. WATER ABSORPTION TEST. 
11. Specimens similar to those described in Section 8 shall be immersed 


*Standards of the American Institute of Electrical Engineers. 


? 

iz 
+ 
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* 
‘a 
o 


Analysis of Varnish 461 


in water at a room temperature of approximately 20° C. (68° F.) for a period 
of 24 hours. Upon removal from the water, the surface water shall be wiped 
off and dielectfic strength tests made immediately as described in Section 9. 

12. The volts at puncture, the thickness of the specimen and the volts per 
mil of thickness shall be reported for each of the ten tests, together with the 
average, Maximum and minimum volts per mil. 


VII. HEATING ENDURANCE TESTS. 

13. (@) For the heat endurance test, specimens shall be prepared by dip- 
ping pieces of thoroughly cleaned, smooth sheet copper or brass about 20 em. 
(7.88 in.) square and about 0.127 mm. (0.005 in) thick into the varnish which 
shall be at the consistency prescribed in Section 5 (bd). 

(b) The specimens shall be dipped twice as prescribed in Section 5 gee 

(c) After removing not less than 1.27 cm. (0.5 in.) from one edge of the 
specimens the number of strips required by Section 14 (a) shall be cut from 
the same edge each 1.9 cm. (0.75 in.) in width. 

14 (a) After setting as shown by the test indicated in Section 6 (b), the 
strips referred to in Section 13 shall be placed in a uniformly heated oven in 
which the temperature is maintained at 100° C. (212° F.) within + 5° ©. 
(9° F.). A strip shall be removed at the end of 1, 2, 4, 8 and 24 hours respec- 
tively and every 24 hours thereafter. These, together with the initial strip, 
Shall be tested as follows at a room temperature of approximately 20° C. 
(68°: F.). 

(6) Each strip shall be bent through 180 deg. over a rod 0.32 cm. (% in.) 
in diameter. The number of hours of baking at which first cracking in the 
insulation occurs shall be noted and reported. 


VIl. HEAT ENDURANCE TESTS. 

15. The specimens to be used for the test for acid and alkali proofness 
Shall be brass rods 1.5 cm. (0.59 in.) diameter, 15 cm. (5.90 in.) long and 
carefully rounded at one end to a radius of 0.75 cm. (0.295 in.). These speci- 
mens shall be dipped three times into the varnish, leaving exposed about 3 cm. 
(1.18 in.) of the rod at the end opposite the rounded end. Each coat shall 
be dried 25 per cent longer than the period determined in Section 7. These 
specimens each shall be prepared for the acid and alkali solutions. 

16. (a) The three specimens shall be suspended in the acid or alkali 
whose effect it is desired to determine to within 3 cm. (1.18 in.) of the end of 
the coated portion of the rod and suitable provision made for detecting the 
change in the electrical resistance between the rod and the solution. (Note 1.) 


Notre 1.—A simple method is to connect a voltmeter between each rod in turn 
and one side of a 110 volt direct current circuit, the other side of the circuit 
being connected to the solution through any piece of suitable metal suspended 
in the solution. The resistance will be inversely proportional to the deflection 
of the voltmeter pointer, that is, the smaller the deflection, the greater the 
resistance. Failure of the material will, therefore, be indicated by a sudden 
increase in the deflection of the voltmeter pointer. 


(b) It is recommended that these tests be made in 10-per-cent solutions 
as follows: 

Sulfuric acid of sp. gr. 1.069 at 60° F. (15.5° CG.) or nitrie acid of sp. gr. 
1.056 at 60° F. (15.5°) ©.) or hydrochloric acid of sp. gr. 1.050 at 60° F. 
(15.5° C.) and sodium hydroxide of sp. gr. 1.115 at 60° F. (15.5° C.). 


462 Analysis of Varnish 


(c) The temperature of the solution shall be kept at approximately 20° C, 
(68° F.). 

17. The resistance between each rod and the solution shall be measured 
once per day and the number of days elapsing before breakdown occurs shall 
be taken as the “proofness” of the varnish. 


IX. OIL PROOF TEST. 
18. (a) To test for the effect of oil, the specimens shall be prepared as 
prescribed in Section 13:(@); 
(b) The specimens shall be dipped and dried as prescribed in Sections 8 


(b), (c) and (d). 

(c) Test pieces shall be cut from the specimens as prescribed in Section 
te (CC). 

19. The effect of oil on the varnish shall be determined by immersing the 
specimens in transformer oil at a temperature of 100° C. (212° F.) for 48 
hours and noting the effect on the varnish as indicated, for example, by wiping 
with a piece of dry white cloth. 


Nore.—Incipient disintegration of the surface of the varnish may some- 
times be detected by examining the oil for turbidity. ‘If a specimen of the oil 
filtered through filter paper can be distinguished from an unfiltered sample 
when the two samples are held in front of a strong light, the oil is turbid. 


X. DRAINING TEST. 
(ALso KNown AS ‘WORKING Viscosity” TEST) 


20. A strip of bond paper 0.064 mm. (2.5 mils) in thickness, 10.2 cm. (4 in.) 
in width and 50.8 cm. (20 in.) in length, shall be immersed in the varnish at 
a room temperature of approximately 20° C. (68° F.) up to a line previously 
drawn across the paper a few inches from the top. The paper shall be with- 
drawn at a slow and uniform rate (about 38 cm. (15 in.) per minute), care 
being taken that the varnish is free from air bubbles. The specimen shall be 
permitted to drain thoroughly at room temperature while suspended in a 
vertical position. It shall then be dried or baked (according to the type of the 
varnish) until dry as determined in accordance with Section 7. 

21. The thickness of the specimen in mils shall be measured at points 5.1 
em. (2 in.), 17.8 cm. (7 in.) and 30.5 em. (12 in.), respectively, from the line 
to which the specimen was immersed. 

29 The thickness of each film in mils at the three points specified in Sec- 
tion 21 shall be recorded. The difference between the thickness at the upper 
point (5.1 em.) and that at the lower point (30.5 em.) shall be taken as a 
measure of the variation in the film thickness caused by draining. 


XI. EVAPORATION TEST. 

22. One hundred cubie centimeters of the varnish shall be placed in a flat- 
bottom erystallizing dish approximately 75 mm. (2.95 in.) in diameter and 45 
mm. (1.77 in.) in height. It shall be heated to a temperature Of 1007 ke 
(37.8° C.) + 2° F. (1.1° C.) for a period of 7 hours, the sample being exposed 
to still air in the open room. 

24. The decrease in volume of the sample shall be taken as the evapora- 
tion, this decrease being determined by noting the amount of water or kerosene 
that must be added to fill the dish to the original level. . 


ee ee ee a eee 


Analysis of Varnish - 463 


Nore.—This test is relative only. That is, it is only suitable for comparing 
one varnish with another when the tests are made simultaneously under 
exactly the same conditions. 


XII. TEST FOR NON-VOLATILE MATTER. 

25. A portion of the sample shall be placed in a stoppered bottle or weigh- 
ing pipette and weighed. About 1.5 g. of the sample shall be transferred to a 
weighed flat-bottom metal dish about 8 cm. (3.15 in.) in diameter, such as the 
cover of a friction-top tin can. The container shall again be weighed and the 
exact weight of the portion of the sample transferred to the weighed dish 
calculated by difference. The dish with its contents shall be heated for three 
hours in an oven maintained at 105 to 110° C. It shall then be weighed after 
cooling. ( 

26. The ratio of the weight of the residue to that of the original sample 
expressed as a percentage shall be taken as the percentage of non-volatile 
matter in the varnish. 


APPENDIX. 


y 

Where it is desired to make dielectric strength tests of solid films of varnish 
(as distinguished from the specimens prescribed in the methods, which are a 
combination of varnish and paper fibers), it is recommended that copper be 
used as the base as formerly required in the methods. The following are the 
directions for preparing and testing such specimens: 

1. (@) Specimens are prepared by dipping pieces of thoroughly cleaned, 
smooth sheet copper or brass about 20 cm. (7.88 in.) square and about 0.127 
mm. (0.005 in.) thick into the varnish which is at the consistency prescribed 
in Section 5 (b) of the methods. 

(b) Hach specimen is dipped twice, once in each direction, in order to give 
a more uniform thickness of coating. The specimen is dried after each dip in 
the same vertical position in which it was dipped. 

(c) Specimens of air-drying varnish are dried in free air after each dip 
at a room temperature of approximately 20° C. (68° F.) for a period 600 per 
cent longer than that determined in accordance with Section 7 of the methods 
provided such period does not exceed 24 hours. 

(d) Specimens of baking varnish are drained and then baked after each 
dip for a period 300 per cent greater than that determined in accordance with 
Section 7 provided such period does not exceed 24 hours. 

(e) The final thickness of the film of varnish on each side of the specimen 
is between 0.044 mm. (0.0018 in.) and 0.052 mm. (0.002 in.). 

2. (a) The dielectric strength of the two films of varnish is determined by 
applying alternating potential to two circular metal disks, 5.08 em. (2.0 in.) in 
diameter and with edges rounded to a radius of 0.64 em. (0.25 in.) which are 
placed in contact with the two sides of the specimen directly opposite each 
other and under a pressure of approximately 05 kg. (1.1 1b.). Starting at zero, 
the voltage is increased uniformly to breakdown at a rate of 0.5 kv. per 
second, except that if breakdown occurs at this rate in less than 40 seconds, the 
rate shall be decreased so that breakdown will not occur in less than 40 
seconds. Ten such punctures are to be made at various points selected at 
random on each specimen, In each test the thickness of the films of varnish 
is to be determined as close to the point of puncture as practicable. : 


Nore.—When necessary, in order to get ten punctures, additional Specimens 
‘should be tested. 


(b) The frequency of the test potential shall be not greater than 100 cycles 
per second, and each part of the testing apparatus shall have a éontinuous 
rating of not less than 2 kva. (preferably larger). The wave form shall be a 


464 Analysis of Varnish 


sine curve as defined, and the voltage shall be measured by methods approved 
by the American Institute of Electrical Engineers. ; 

(c) The voltage may be controlled by any approved method which does 
not distort the wave form beyond the limits prescribed above and which does 
not subdivide the voltage in steps greater than 500 volts. The apparatus shall 
comply with the Standards of the American Institute of Electrical Engineers. 

8 The volts at puncture, the net thickness of insulation and the volts per 
mil of net thickness shall be reported for each of the ten tests together with 
the average maximum and minimum volts per mil. 


ee 


CHAPTER XXV 


MISCELLANEOUS TESTS ON VARNISHES 


There is given below a series of miscellaneous tests which 
may be of general interest to the varnish chemist. 


Testing the Acid Value of Varnishes.—In a study of various 
methods to determine the acid value of varnish products, a sub- 
committee of the Committee on Varnish of the American 
Society for Testing Materials sent out samples of several var- 
nishes made by varying processes and containing different 
gums and oils. Five different methods for determining the 
acidity were included. Of these methods, Nos. 3 and 4 were 
found to give the most closely checking results. Method 5 was 
also found desirable on account of good end points obtained, 
and since that method can be used for dark colored varnishes, 
it should be of general interest. These three methods are 
presented below. 


Method III (suggested by EK. A. Stoppel).—Materials.— 
Weight of sample taken, 10 g. Volume of ether, U. S. P., 100 
ec. Alcoholic KOH or NaOH 0.5 N. Indicator 1 per cent alco- 
hohe phenolphthalein. : 

No heating is required for solution, although 2 to 5 minutes 
with shaking is usually allowed for complete solution. Titra- 
tion with shaking is continued until a pink color is reached. 
If the acid number of the varnish is very high, 0.2 N alkali is 
recommended. The method, of course, is applicable to oils 
and resins as well as varnish. 


Method IV (suggested by M. Neidle).—Applicable to ma- 
terials whose color will not mask the phenolphthalein end 
point. 

To a suitable weight of sample in a 300 to 500-cc. Erlen- 
meyer flask add 50 ec. of benzol or xylol. Mix until uniform, 
heating if necessary. 

Add 50 ce. neutralized denatured alcohol, and titrate with 
approximately 0.5 N aqueous NaOH, using phenolphthalein as 
indicator. If more than 25 cc. of NaOH has been used, add 
00 ee. more of neutralized denatured alcohol and continue the 
titration until, after shaking, the color persists for at least 
two minutes. Vigorous shaking during titration is essential 
for the proper distribution of the acid. | 

When the final end point is taken, the volume of alcohol 
should be twice that of the water in the mixture. 


466 Miscellaneous Tests on Varnishes 


Method V.—Applicable to materials whose color would or- 
dinarily mask the phenolphthalein end point, for example, as- 
phaltum varnishes, cotton pitches, very dark gum goods; also 
useful where metallic soaps are precipitated when alcohol is 
added. 

To a suitable weight of material, add 50 ec. of benzol or 
xylol. Mix until uniform, heating if necessary. Then add 
50 ec. of carbon tetrachloride, a mixture of 50 ce. of neutral- 
ized denatured alcohol and 10 ce. of water, 14 teaspoonful of 
sodium chloride and a little phenolphthalein indicator. After 
mixing well, a clear layer should quickly separate on top. 

Now, titrate with 0.5 N aqueous NaOH, with vigorous shak- 
ing until, on standing, the top layer is pink and remains so for 
at least two minutes. 

If more than 15 ec. of NaOH has been used, add 50 ce. more 
of neutralized denatured alcohol, shake, and continue the 
titration if the color has been discharged. When the final end 
point is taken, the total volume of alcohol should be at least 
twice that of the water in the mixture. 

A first determination may be over-stepped and brought back 
with 0.5N H.SO,. The second determination should then give 
a sharp end point within one or two drops of the alkali. 

Note.—The purpose of the carbon tetrachloride is to obtain 
a solvent layer of high specific gravity. Water is added to the 
aleohol to destroy the miscibility of the latter with the ether 
solvents present. The sodium chloride reduces the tendency 
towards emulsification. 


Testing Gas Resistance.—The gas test referred to in Bureau 
of Standards Cireular No. 117, while having proved generally 
satisfactory, is according to one observer, not as satisfactory 
as one in which fresh flowouts of the varnishes are placed in a 
small cabinet two feet square, in which two Bunsen burners 
with luminous flames are just burning. Comparisons can be 
made as soon as the tack-free period of drying is passed. This 
method of test is practical and severe, and has been used with 
satisfactory results. | 

A more elaborate and decisive method of testing a varnish 
for resistance to gasses has been devised by W. W. Bauer.” 
It consists of passing nitric oxide through a bell jar in which 
are placed the panels to be tested. 


Testing the Livering Properties of Varnishes.—In deter- 
mining whether a varnish will be suitable as a mixing liquid 


* Ind. and Eng. Chem., 18, 1249 (1926). 


467 


N 


Miscellaneous Tests on Varnishes 


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468 Miscellaneous Tests on Varnishes 


in an enamel, the writer has generally used for this purpose 
a paste made of 80 parts by weight of zine oxide and 20 parts 
by weight of refined linseed oil. To 40 parts of this paste, 60 
parts by weight of varnish is added, and the mixture thor- 
oughly stirred. It is allowed to stand in a small, partially 
open evaporating dish for a period of six weeks. The charac- 
ter of skin formed upon the surface should be noted. If var- 
nishes contain a very large amount of drier, the skin formed 
will probably be very brittle and comparatively thin. Var- 
nishes which contain a small amount of drier generally pro- 
duce skins which are tougher and thicker. The use of var- 
nishes containing an excess of manganese very often gives a 
pink tint to the enamel mixture. If livering occurs, it may 
be detected by roughly gauging the consistency of the paste 
with a spatula. If sufficient of the enamel has been made up, 
its increase in body may be watched by running mobilometer 
tests every week. There is given below a chart showing the 
results of tests of the above character, which were conducted 
upon a number of varnishes. 


Alkali Increase Test for Tung Oil Varnishes.— When a solu- 
tion of sodium or potassium hydroxide is added to certain 
tung oil varnishes, the resulting mixture becomes extremely 
viscous. Other tung oil varnishes, differently processed, show 
a much smaller increase in viscosity after the addition of an 
equivalent amount of alkali. Two batches made on approxi- 
mately the same formula may have the same acid value and 
initial viscosity, yet through differences in manipulation or 
cooking, may differ greatly in viscosity after the addition of 
alkali. When linseed oil varnishes are alkali treated, the 
viscosity increase is in general much smaller than in the case 
of tung oil varnishes. 


The writer has recently applied a so-called ‘‘ Alkali Increase 
Test’’ to a number of commercial varnishes. Hxperiments 
were also made on a tung oil varnish of fixed composition. 
The results are given in the pages which follow. ‘This test, 
which has previously been used in research work, presumably 
yields a measure of the extent to which the oil has been poly- 
merized during cooking. It may also indicate roughly the 
collodial condition. The test is made in the following man- 
ner. The viscosity of the varnish is first measured by one 
of the usual methods. To a fresh portion of the sample, a 


Miscellaneous Tests on Varnishes 469 


fixed quantity of definite strength alkali solution is added and 
the viscosity of the mixture determined at the same tempera- 
ture as used for the untreated sample. 
It is necessary that standard conditions be observed in mak- 
ing the test. The results obtained with a given varnish are 
Note.—The original method of alkali increase was developed by one of the 


writer’s former associates, R. E. Coleman, working with Messrs. Seaton, 
Sawyer and Probeck. Acknowledgment for this early work is herewith made. 


greatly affected by temperature, concentration of the alkah, 
time elapsing between alkali addition and viscosity reading, 
ete. In the experiments herein described a Doolittle visco- 
meter was used, readings being taken with a one-inch spindle 
in all cases. The thermometer employed was graduated in 
tenths of a degree Centigrade; the temperature being main- 
tained as nearly as possible at 25° C. during determinations. 
A 10% solution (2.5 N) of sodium hydroxide was used. 


Method Used for Taking Alkali Increase.—Measure out 
exactly 10 cc. of 10% (2.5 N) aqueous NaOH solution in a 
small graduate. Measure 200 ec. of the varnish in a 200 ce. 
graduate. Pour the varnish into a 300 ee. beaker and allow 
the cylinder to drain for exactly one minute. Add the meas- 
ured quantity of NaOH solution to the varnish quickly, at the 
same time stirring vigorously. Continue the stirring for ex- 
actly two minutes, then transfer the mixture to the viscometer 
cup. Allow to stand in the viscometer bath for thirty minutes 
after stirring the varnish has ceased. (Bath should previously 
have been brought to desired temperature, 25° C.)- Main- 
tain bath as nearly as possible at 25° C. for the required thirty 
minutes, taking a temperature reading a few minutes before 
the viscosity reading. Read the viscosity exactly thirty min- 
utes after completing the stirring. 

Several viscosity and alkali increase readings should be 
taken. In the writers’ experiments, the second alkali increase 
reading appeared to be the most accurate and most readily 
reproducible, hence was taken as the correct value. 


Lest on Commercial Varnishes——Table 59 gives the results 
of tests on commercial lots of well known brands of varnishes. 
Table 59 indicates that there may be no relation between acid 
value and the increase in viscosity after the addition of alkali. 
For instance, Sample No. 3, which had the highest acid value 
of the samples examined, had an alkali increase viscosity 


470 Miscellaneous Tests on Varnishes 


which was easily measureable. Sample No. 6, on the other 
hand, had the lowest acid value but showed a much greater 
increase in viscosity with alkali addition than did No. 3. 

Of the eleven samples examined, the alkali increased viscos- 
ity was so great as to be measurable in only four cases. It is 
probable that readings could have been made on these var- 
nishes if they had first been thinned to a greater extent with 
turpentine. This procedure is suggested to those wishing to 


TABLE 59 
en Nn nares eee 


Viscosity Alkali Increase Acid Oil Used in 


Varnish at 25° C. Viscosity at 25" 43 ape Varnish 
a 
4S Miia eee 25.0 42.0 7.5 Linseed 
9 Boot. Tope 45.0 Too great to measure 11.4 Tung 
3 ht eIOt ees 15.0 107.0 22.0 Linseed 
4... Agricultural... 45.0 Too great to measure 14.0 Mostly tung 
5 o> Mnterior aware 28.5 137.0 20.7.» Lanseed 
6) Spare ncc ae 28.5 Too great to measure 4.1 15 tung to 1% lin- 
seed 
To Motor Caria. dia 39.0 Too great to measure 9.3 20 tung to 30 lin- 
seed 
8...c Floor Gaes re ee 32.0 127.0 12.9 % tung to 14 lin- 
seed 
0. > Motor Car ses 28.0 Too great to measure 6.8 Mostly tung 
10. Rubbing Swe: 98.5 Too great to measure 21.9 Tung 
11° Bootibonicrsee 44.0 Becomes solid 7.3. Lang 


a 


do further work on the method. Viscosity reading might also 
be obtained after two minutes rather than thirty minutes, on 
such products as are very high in viscosity after alkali addi- 
tion. 

Three of the four varnishes listed above contained linseed 
oil only. The others consisted of linseed oil and tung oil. ‘The 
resin content, which was unknown to the writers, undoubtedly 
had a considerable effect on the reading. 


Possible Application of the Test—While the test might 
find application as a control test in processing tung oil var- 


Miscellaneous Tests on Varnishes 471. 


nishes, it would probably prove most useful in research work. 
For instance, it has been found that an oil or varnish which 
shows a high increase in viscosity with alkali addition fre- 
quently livers or thickens up with active pigments even though 
it may be practically neutral. 


When considered in connection with viscosity the test will 
also indicate variations in processing. Two batches of a 
treated oil or varnish made on the same formula may show 
identical viscosities, yet through variations in the cooking or 
in the bodying of the materials in the formula, may show en- 
tirely different alkali increase factors and behave differently 
when mixed with pigments. 


Preliminary tests have also shown that drying characteris- 
ties may vary with changes in the alkali increase. 


In routine work the test might be used to determine whether 
different batches of the same varnish were coming through 
the same. Each varnish so processed as to have certain defi- 
nite characteristics would show an alkali increase which might 
vary between fairly narrow limits without materially affect- 
ing those characteristics. These limits, if once determined 
and thereafter adhered to, should assist materially in insuring 
uniformity. Instead of testing each individual batch, a tank 
might be tested after having stood a specified length of time 
and before being canned. 


Testing the Speed of Evaporation of Varnish Thinners.— 
Oleo-resinous varnishes usually contain from 40 to 60% of 
‘‘thinners’’ such as turpentine, mineral spirits or similar or- 
ganic volatile liquids having quite wide variations in boiling 
points. The rate of drying of such varnishes has been con- 
sidered as dependent to some extent upon the character and 
amount of thinners present. 

That mineral spirits will evaporate more slowly than tur- 
pentine from a varnish film is well known. ‘The effect of the 
type of hydrocarbon upon the rate of evaporation has hereto- 
fore apparently lacked investigation. The proportion of the 
various fractions of widely different boiling points which 
make up the hydrocarbon thinning liquids is also a matter 
of considerable importance. In addition to the influence of 
the above factors upon the drying of a varnish may be men- 
tioned the effect of the thinner upon the viscosity of the thin- 
ned varnish. The experiments described herein were con- 


472 Miscellaneous Tests on Varnishes 


ducted for the purpose of securing information along the 
above lines. 

In order to secure exact data on the subject a series of 
thinners of widely varying boiling points—namely, turpen- 
tine, mineral spirits, solvent naphtha, benzine and benzol— 
were experimented with. The varnish bases were prepared 
in a varnish plant in 100-gallon kettles. One was a short oil 
interior rubbing varnish containing about 7 gallons of varnish 
makers’ linseed oil to 100 pounds Kauri gum; the other a long 


Ficure 181 


Weighing Bottle Used in 
Tests 


oil spar varnish containing about 24 gallons of Tung oil and 12 
gallons of alkal-refined linseed oil to 100 pounds of combined 
varnish resins. These varnish bases were sent to the labora- 
tory without added thinner. 


The varnish solutions were prepared by warming the base 
until it became liquid enough to incorporate the thinner, care 
being taken to avoid excessive heating. Both base and thin- 


473 


Miscellaneous Tests on Varnishes 


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476 Miscellaneous Tests on Varnishes 


ner were very carefully weighed* before mixing. All samples 
were reweighed after mixing to insure that there had been no 
appreciable loss of volatile during the mixing. In no case, 
except with certain of the lower individual fractions, was the 
loss sufficient to require further addition of thinner to secure 
the desired percentage of ingredients. The amount of thinner 
did not vary in any case by more than a fraction of 1% from 
that shown in the tables. 3 


In Table 60 is presented a distillation chart of the various 
thinners used. The mineral spirits were of a high grade com- 
mercial type meeting the specifications of the Federal Specifi- 
cations Board. Benzine, benzol, and solvent naphtha were 
average commercial samples of good quality. The turpentine 
was a few months old and left a rather high viscous residue, 
but was satisfactory otherwise. 


Small bottles were tightly fitted with corks into which were 
fastened small brushes. (See Fig. 181.) A few grams of var- 
nish were poured into one of the bottles, and the cork set 
tightly in place so as to prevent evaporation. The bottle, with 
its brush and contents, was then weighed. The cork was then 
removed with its contained brush and the varnish thereon 
quickly applied to a weighed glass plate. The bottle was 1m- 
mediately corked and reweighed. The difference in the weight 
of bottle and contents before and after applying the film gave 
the weight of the film. 


Similar work has just been conducted by the writer on vola- 
tile solvents used in making Pyroxylin Lacquer Coatings (see 
page 637). 


* Results throughout are based on percentage of volatile by weight. 


ee ee ee ne me ge ee ee 


ee ee es Neg Ee 


a ee oe 


Miscellaneous Tests on Varnishes 477 


Testing The Influence of Thinners.—There is given below 
the approximate viscosity of varnish thinned with various 
thinners in the proportion of 50 parts by weight of the same 
varnish base and 50 parts by weight of thinner. These tests 
were made with the Gardner-Holdt Viscometer tubes: 


Paraffin Petroleum Thinners 


Poises 
I ye sg. is vice bs cyaiwid oe sins sicie eu sestedtelmesaes 1.65 
CREE ET CGLOI ees dacs vcs oie cw p-aidc Gav ese rence ca vens 2.00 
Meremierntcarmiineral Spirits “A”... oi. ce cece pews scacuscevus 2.00 
LASSER US 055 Sa iu a a a 3.20 
OE EA CEROIUY cre ovine y's eh cislc'e fcc des Sick Bele edwied cuales bees 3.20 
Sua EE CLOT peice. Aon sec bob ccksd bgicelelece’s'va,c'e snes acuesdae 4.00 
Equal Mixture of Fractions (175-181° C. and 225-235° ©.)...2.. 6.00 
CECA oe. be. sis chs ns vc cv ci vyy eos coe no suites on acee 7.00 
ee er CULT ie on vets s vic wp c'bib es o'd'saice ges ebveeeesaee 9.00 

Cyclic Hydrocarbon Thinners 

RUIN MEER ect oo Ox ba cic aslo dete chic soaaceadesvacdees 4.00 
TPR TINENEA ee RS, cit, wince Gin aodweceebeecsaces 8.00 
SMM MMM Mec eh oo i saw eagle ois. eae s Ace's Gc eens cease 10.00 


Relation Between Kauri Reduction and Exposure Tests.— 
There seems to be some relation between the results obtained 
with the kauri gum reduction test for elasticity of varnishes, 
and results obtained by actual exposures of such varnishes. 
The writer recently exposed 26 varnishes which had previously 
been tested for elasticity. The results of the exposure tests 
divided the varnishes into two groups, namely, poor and good. 
Ten of the varnishes had failed in the kauri gum reduction 
test, and eight of these appeared in the poor group on expo- 
sure. While these tests were not extensive and insufficient 
information is available to make a broad statement on the sub- 
ject, they would suggest that a relation seems to exist with 
certain classes of varnishes. 


A. S. T. M. TENTATIVE METHOD OF TEST FOR 
ELASTICITY OR TOUGHNESS OF VARNISHES BY 
ADDITION OF LINSEED OIL 


1. This method applies to varnishes which are less elastic or tough than 
zero Kauri reduction in the present Standard Methods of Testing Oleo-Resin- 
ous Varnishes (Serial Designation: D 154) of the American Society for 
Testing Materials. The method of test is identical with the present test 
except that the 33%-per-cent solution of Run Kauri in turpentine is replaced 
by a 66%4-per-cent solution of heat-bodied linseed oil for proportionately in- 
creasing the elasticity of the varnish under test. 


478 Miscellaneous Tests on Varnishes 


LS 


PREPARATION OF STANDARD HEAT-BODIED LINSEED OIL 
2. A high grade of alkali-refined linseed oil of an acid number of less than 
1.0 shall be heated in an open kettle at a temperature of 300° C.+ 5° C. (572° 
F.+9° F.) until the viscosity of the oil after cooling shall be between 6 and 
10 poises at 25° C. 


STANDARD BODIED-OIL SOLUTION 
3. A quantity of the bodied oil shall be reduced with one-half its weight 
of pure redistilled turpentine, using only that portion of turpentine distilling 
between 158 and 170° C. (308 to-338° F.) 


PROCEDURE 

4. The addition of the standard bodied-oil solution to the varnish, the 
flowing on panels, baking and bending shall be conducted exactly .as in the 
Kauri reduction test described in the present Standard Methods D 154. In 
reporting results, the minimum percentage of the oil solution that must be 
added to the varnish, based on its non-volatile content, so the final mixture 
when flowed on tin and baked does not crack on the subsequent bending over 
a 3 mm. rod shall be reported. 


CHAPTER XXVI 


COLOR STANDARDS FOR VARNISHES 


Some plant managers consider it of importance to gauge the 
color of certain varnishes so that batches made up will closely 
approximate those produced at previous periods. The usual 
means of accomplishing this is to keep samples for compari- 
son. It has been found, however, that varnish samples kept 
in glass and exposed to hight may show a substantial change 
in color. Another method that has been used to sofne extent 
is to make up a solution of 3 grams of potassium bichromate 
in 100 ee. of pure sulfuric acid, limiting the darkness of var- 
nishes to the depth of color shown by such a solution. This 
solution, however, has the disadvantage of being quickly re- 
duced, the yellow soon being replaced by a green tint. This 
change is sometimes noticeable on a few hours’ standing. The 
use of such a standard would, therefore, require the making 
up of fresh solutions from day to day. A suggestion has been 
made that a varnish slightly lighter in color than the standard 
solution of bichromate referred to above be prepared and pre- 
served as the standard for comparison. This, however, is not 
always satisfactory, owing to the actual color changes which 
take place even in varnish and to the limitation of having only 
one standard rather than a number of graded colors. 

The writer and P. C. Holdt have found a number of other 
substances that fairly match varnishes in color but which un- 
fortunately are not permanent. For instance, iodine solutions 
fade in the light, metallic salt solutions such as ferric chloride 
are affected by the alkalinity of glass containers, ultimately 
throwing down precipitates and becoming lighter in color. 
Organic dyestuffs experimented with have proved either de- 
ficient in red or yellow, or subject to rather rapid loss of color 
upon standing in the light. | 


In the experimental work that has been conducted an at- 
tempt was made to use a set of cube rosin standards ranging 
from Gto WW. These were first melted and poured into per- 
fectly dry, clear glass tubes such as are used for making bub- 
ble viscosity test on varnishes. It was found, however, that 
upon cooling the rosin would crystallize in the tubes, some- 
times depositing long crystalline needles against the glass, 


480 Color Standards for Varnishes 

causing an opacity which would obscure the color. Moreover 
the gradations of color shown by the rosin standards were en- | 
tirely unsatisfactory. 

Asa result of a series of extended experiments, it was found 
that the substance known as caramel (burnt sugar), when 
diluted with water, produced clear solutions which exactly 
match the yellow amber and red ruby colors produced by 
various types of varnishes. In fact, the color effects produced 
by different strengths of aqueous solutions of caramel more 
closely approximate the colors of varnishes than any other 
substance experimented with. After considerable prelimi- 
nary work, a series of 12 caramel solutions varying in color 
from almost water white to that of the darkest varnish, was 


TABLE 61 
ce. of caramel 

Solution No. | ce. of water. solution. 

14.5, Cee 99.8 0.2 

De te ee ptiee aes 99.6 0.4 

ps SA eis ei 98.9 Le 

Ao ee Pee ' 97.6 2.4 

SWeterar ce ea 96.3 Bet 

6, vcusennae 92.6 7.4 

Tn eee 88.9 Fisk 

Rak Ree Si 18.5 

Mae rite graces i "22 27.8 
10 6.5 ee See 55.6 44.4 
1d. ee eee 40.8 59.2 
12 05 se eee tony 4 T7.8 


prepared from a strong solution made by dissolving 165 grams 
of liquid caramel syrup in 450 ce. of water.* This concentrated 
solution was diluted with various proportions of water to 
secure the desired range of colors met with, and ranging from 
standard turpentine to the darkest grades of oleo-resinous 
varnish. The concentration of each solution is given in Table 
61. In making the dilutions, both water and caramel solu- 
tions were accurately measured from a burette. 

The solutions prepared as above were sterilized to prevent 
fermentation and consequent change in color. In determining 
the best method of sterilization, one set of samples was steril- 
ized by heating a weighed amount of solution to boiling for a 
few minutes in an Erlenmeyer flask fitted with an air con- 
denser. After boiling, the flask was again weighed and a 


* Commercial caramel varies greatly in concentration. Several samples 
were purchased by the writer from various drug stores. The strength, however, 
may easily be adjusted, using as a standard for one sample 3 grams of potas- 
sium bichromate dissolved in 100 cc. pure sulfurie acid (spec. grav. 1.84). 


Color Standards for Varnishes 481 


small amount of sterile water added to replace that driven off 
by the heat. In making up another set of samples, one-half 
of one per cent of sodium benzoate was added to each solution. 
This sample was not boiled. A third set of solutions was 
made up but was not sterilized. These three sets of samples 
were examined at the end of three months. In the set that had 
not been sterilized, there were large masses of fuzzy agglomer- 
ates, indicating that considerable fermentation had taken place. 
In the set sterilized by heat, there were small amounts of 
fuzzy masses (possibly caused by some contamination in trans- 
_ ferring the solutions to the sterilized tubes). The set of sam- 
ples which had been sterilized with sodium benzoate showed 
absolutely no evidence of fermentation. It was decided, there- 
fore, that this method of sterilization is the best. Tater it 
was found advisable to use 25 per cent of alcohol in the solu- 
tions. 

To test the permanency of the suggested color standards, 
the color strength of each solution was determined by means 
of the Lovibond tintometer in terms of both red and yellow. 
These readings were then repeated at intervals of from two to 
three weeks to determine whether any change was taking 
place. The same set of tubes was used throughout, being 
tightly corked after each reading. They were kept in the 
laboratory upon a table in the light so as to afford every op- 
portunity for color changes. The results on a series of four 
readings are given in Table 62. It will be noted that there 
was practically no change in the color of these standards be- 
tween the first and the final readings. Any minor changes in- 
dicated were so slight as to be attributable to experimental 
error in observation rather than to change in the color of the 
solution. As a check on the results, there was made up 
on Oct. 12th another set of the standard solutions, by using 
the same lot of caramel diluted to the same concentration and 
sterilized by the same process. When these solutions were 
compared with those made up three months before, upon 
which the readings had been made, no change was shown. 

From a strictly scientific point of view, it would be more 
accurate to measure color strength of varnishes in terms of 
wave length and to look for color changes with the aid of a 
colorimeter. However, a variation in color that cannot be de- 
termined by the unaided eye is of no importance in the pres- 
ent connection, aS approximations only are desired. More- 


482 Color Standards for Varnishes 

over, because of the high cost of accurately standardized col- 
orimeters, such apparatus would not be available in most var- 
nish factories. It is the writer’s belief, however, that a sim- 
ple form of apparatus, such as is suggested in this chapter, 
might be produced by anyone interested and quite satisfac- 
torily serve the purpose for commercial work. 


TARLE 62.—Color Strength of Caramel Solutions (Lovibond Tintometer ) 


Ist Reading 2nd Reading 3rd Reading 4th Reading 


Sam- | Size July 7th. July 15th. July 28th. Aug. 22nd. 

ple (ell: fe eee eases Sete 

No. i F 

Yellow. | Red. | Yellow. | Red. | Yellow. | Red. | Yellow. | Red. 

oe eee 1" 2.0 0 2.0 0 2.0 0 2.0 a 
CUR aS 4" 3.0 2 3.0 a 3:0 2 3.0 7 
ys or ae 1” 5.0 we 5.0 4°3 5.0 io 5.0 iy 
aes ai 1” $6 we) 8.5 3 8.5 oO 8.5 2 
ee, 14” 16.0 ioe aka TAVIS 7 nee i: ae 
fea: 16” | 26.0 O44 26.0 Lesa 1. 35) 2540 1.35 
ik: some 16” | 36.0 2:35 5070 2.6 | 36.0 3. OF 36.0 3.0 
ieee & yy" | 30.0 1/75) 208 1.75) 30.0 2.04. 30-0 lea 
LG ae Wy" | 42.0 4.0 | 42.0 4.5 | 42.0 4.7} 42.0 4.5 
AA See iy") 51.0 bi Ole 8.0} 51.0 roe Oe eras 3 Be 7.5 
12 Ase 1%” | 61.0. | 12.5 | 61.0 | 12.5) GIO) a ee 


Nore: Because of the very light color (match for turpentine) of Sample No. 1 
this was not included in the readings. 


In order to test the permanency of the color of varnishes, 
samples of exterior varnish, floor varnish, and rubbing var- 
nish of well known commercial brands were selected. These 
were placed in tubes in the original undiluted condition, and 
also diluted with 25 per cent and with 50 per cent of pure 
spirits of turpentine. Five sets of tubes thus prepared were 
sealed airtight in viscosity bubble varnish tubes. ‘Two sets 
of these sealed samples were wrapped separately in heavy 
paper, placed in a box so as to completely exclude all light, 
and so protected until the time of making a reading for color 
value. Two other sets were exposed to ordinary daylight in 
the laboratory but not to the direct rays of the sun. Read- 
ings were taken on one set of the sealed tubes kept in the dark 
and one set in the light, at the end of periods of one month. 
On the sets kept in the dark, no appreciable change was ob- 
served at the second reading. The sets kept in the light, how- 
ever, showed considerable change. Readings on the latter are 
given in Table 63. The change in some of these was suffi- 


Color Standards for Varnishes 483 
— eee SSS 
ciently great to be easily detected by the eye without the use 
of an instrument. It is very interesting, however, to note that 
the change is not always a lightening of color. For instance, 
some samples had become very much darker in color. 


TABLE 63.—Readings on Varnishes Haposed to Light, Showing Changes in 
Color Values 


Ist Reading 2nd Reading ord Reading 
Aug. 22, 1921.| Sept. 13, 1921.) Oct. 11, 1921. 

Sample. — BRE ey ee a Fe Eas, eee ees) te” ead ba ae acae 
| Yellow. | Red. | Yellow. | Red. | Yellow. | Red. 
Exterior Varnish....... yy” 42 1.1 36 ia 33 1.3 
Ext. Varnish 25% Turp..| 14” 32 0.8 30 0.5 28 0.5 
Ext. Varnish 50% Turp..| 14” 28 0.5 23 0.5 21 0.4 
Seerioor Varnish.......... 4? 65 ou 62 Oyo 61 3.0 
_ Floor Varn.+25% Turp.| 14” 52 171 50 1.3 45 1} 
Floor Varn.+50% Turp.| 1%” 36 0.1 34 0.1 32 0.1 
Rubbing Varnish....... yy" 42 5.6 43 6.2 46 6.2 
Rubbing Varn. 25%Turp| 14” ol 4.3 36 4.2 38 4.0 
Rubbing Varn. 50%Turp| 1%” |... 42 5.0 48 6.0 50 6.0 


The same combination of glasses was used in successive readings to deter- 
mine whether there had been any change in color. This procedure is necessary 
because the combined thickness of the glasses affects the reading. For in- 
Stance, a Sample may match glasses 16+ 14+ 8 but be lighter than a combina- 
tion of glasses 16+ 14+ 6+2. In the Second and third readings, the same 
combinations of glasses as were found to match the sample in the first readings 
were tried. Changes were then made until the glasses matched the samples. 
In Tables 62 and 63 only total readings are given. 


In considering the set of 12 solutions reported on Table 62, 
it was found possible to omit samples 3 and 5. This left a 
series of 10 standards which during the past year have been 
slightly revised in gradation. Standard No. 1 is now equiva- 
lent to the Standard for turpentine in accordance with the 
U. S. Interdepartmental Specifications for that material. 
Standard No. 9 in the new set is the equivalent of the bichro- 
mate solution used as the standard in accordance with the 
Federal Specifications Board Specifications for Spar Varnish. 
These ten new standards made up as outlined and now con- 
taining 25 per cent of alcohol to further guard against fer- 
mentation, are placed in tubes and hermetically sealed. 
This method of sealing has been found to be the only one that 
is satisfactory. These tubes are placed in special carrying 
eases such as that used for the Bubble Viscosity Test Stand- 


484 Color Standards for Varnishes 


ards described on page 32. The labels used on the carrying 
case with methods for use are given below. 


Combination of Glasses in Lovibond 
Tintometer to Match Sample 


eee aT 
Solution Size of cell 
No. inches Yellow Red 
1 % 0.0 0.0 
2 VY 0.38 0.0 
3 % 3.0 1.0 
4 % 14.0 3.6 
5 % 17.5 6.0 
6 % 21.0 20.0+1.0 10.0 
7 4 15.0 : 8.0 
8 iy 41.0 12.0+14.0+15.6 12.0 
9 WY 51.0 15.0+16.0+20.C€ 16.0 
10 A 56.5 16.5+20.0+ 20.6 34.0 14.04 20.0 


Directions for Using Color Standards.—Fill one of the extra tubes with 
the sample to be gauged for color. Compare it with the suggested standards. 
The sample and standard tube being compared should be held close together 
and observed by transmitted light. Readings of each with the Lovibond tinto- 
meter are presented. 

No. 1 is approximate to limit of color for turpentine, Federal Specifications 
Board Specifications, Recommended Standards for Turpentine. 

No. 9 is approximate to limit of color for Spar Varnish, Federal Specifica- 
tions Board Specifications, Recommended Standards for Spar Varnish: 3 grams 
potassium bichromate to 100 ce. sulphuric acid Sp. Gr. 1.84. 


CHAPTER XXVII 
-ANALYSIS OF MIXED DRIERS 


While composed mainly of organic material, mixed driers 
may contain silicon, iron, aluminum, calcium, magnesium, 
phosphorous, copper, zinc, lead, manganese and cobalt. Some 
of these are present in linseed oil, oils and resins, some may 
be accidentally introduced (as from kettles) and some are 
purposely added. Although the last three only are usually 
determined, the possible interference of the others must be 
considered in any scheme of analysis. 

When an accurate determination of the percentage of 
various metallic driers in oils and varnishes is desired, it is 
eustomary to slowly ignite the mass and examine the ash. 
Wet oxidation of such large amounts of sample as are 
necessary, with nitric and sulphuric acids is impracticable 
and rapid ignition at high temperatures will result in the 
volatilization of some or all of elements such as lead and zine. 

The ash is usually extracted with nitric acid, on account of 
the presence of lead. It is to be borne in mind that direct 
determination of lead as sulphate is not permissible in the 
presence of calcium, that the bismuthate method for man- 
gwanese can not be used in the presence of cobalt, and that 
most methods for the determination of cobalt require the 
elimination of several of the above constituents. 


RECOMMENDED PROCEDURE* 
(For lead, manganese and cobalt) 

Ash 50-200 g. of the drier in a muffle at the lowest possible 
temperature. Dissolve the ash in dilute nitric acid (1:1), 
adding hydrogen peroxide to facilitate solution in case per- 
oxides are present. Filter and dilute to measured volume. 

Determine manganese in an aliquot of the above solution 
by the persulphate-arsenite method if cobalt is present and 
by either this method or the bismuthate method in the ab- 
sence of cobalt. (A. S. T. M. Standards, 1921, pages 514-16.) 

Determine lead in another aliquot by first precipitating 
with hydrogen sulphide in a solution of suitable acidity, dis- 
solving the precipitate in hydrochloric acid with the aid of 


* Suggested by P. H. Walker. 


486 Analysis of Mixed Driers 


a little nitric acid toward the end, if necessary, and then finally 
precipitating the lead as sulphate or as chromate by the 
usual procedures. } 

Determine cobalt in another aliquot by first evaporating 
with sulphuric acid to eliminate lead, then carrying on a 
double precipitate with ammonia to eliminate iron and alumi- 
num, and finally adding potassium nitrite to the combined 
ammoniacal filtrates after acidification with acetic acid. In 
ease the amount of cobalt is very small, a preliminary con- 
centration should be carried out by treating the ammoniacal 
filtrates with ammonium sulphide, filtering, dissolving the 
sulphides, making the solution alkaline and then proceeding 
with the acidification and addition of nitrite. 

If a determination of zinc is desired, it may be carried out 
in the filtrate from the hydrogen sulphide separation of lead. 
In this ease, the filtrate should be treated with sulphuric acid 
and evaporated until sulphuric acid is evolved. The cooled 
solution should then be diluted, neutralized until it contains 
approximately one hundredth normal sulphuric acid and zine 
precipitated in the sulphide which can then be ignited and 
weighed as oxide or sulphate. For determining the efficiency 
of a drier, see methods outlined under Federal Specifications 
Board Specifications for Drier, back of this volume. 

Quick Test for Driers in Varnishes and Pigmented Enamels. 
—A quick test communicated to the writer by C. L. Schumann,* 
for determining such constituents, is as follows: 3 

Weigh 50 grams of varnish into a 500 ec. Erlenmeyer flask, 
add 60 ce. of denatured alcohol, 60 ce. concentrated hydro- 
chlorie acid, and a few glass beads. Heat on.a hot plate un- 
til most of the alcohol is boiled off. -Add about 12 oz. of water 
and heat to boiling, subsequently filling up to the neck of the 
flask with turpentine substitute. Heat and let stand until a 
clear separation is noted. Siphon off the turpentine substi- 
tute and add another portion thereof. Repeat process. Kvap- 
orate the water solution to a sufficient concentration for de- 
termining metals present. This water solution will contain 
all the metal portion of the varnish. The same method as 
above may be used with enamels, but only 2 or 3 grams is re- 
quired. i 


*Pratt and Lambert Laboratories, 


” a 3 Ai te . 
sc con iene 


Analysis of Mixed Driers 487 


Morrell* gives certain qualitative tests for lead, mangan- 
ese, and cobalt driers in varnish, that are referred to here- 
with. For detecting the presence of lead, the varnish or 
drier is diluted with about an equal quantity of light petro- 
leum ether. A dilute solution of potassium bichromate is 
added, and the mixture shaken thoroughly. If lead is pres- 
ent, there will be no sharp line of division between the water 
and the diluted varnish, owing to the formation of a precipi- 
tate of lead chromate at the dividing surface, and also on 
the walls of the test tube. The contents are poured out of 
the tube and the walls carefully examined for the presence 
of yellow lead chromate adhering to the sides. The addition 
of some ammonium sulphide, which will turn the chromate 
to a dark color, is confirmatory. This test works in the 
presence of manganese and cobalt. 

For the presence of manganese, 2 or 3 ec. of the varnish 
are thinned with from 3 to 4 ee. of petroleum ether and 
shaken for about 8 minutes with moderately dilute nitric acid. 
The aqueous layer is withdrawn and boiled with a pinch of 
manganese-free lead peroxide. On settling, a violet color 
indicates the presence of manganese. This test can be per- 
formed directly in the presence of lead and cobalt. | 

For the presence of cobalt, the varnish is diluted with light 
petroleum ether, and then shaken with dilute hydrochloric 
acid. The water layer is separated, and to it there is added 
an excess of ammonium sulpho cyanate with a little concen- 
trated potassium acetate and 2 or 3 drops of saturated tar- 
taric acid (to remove ferric sulpho cyanate), a blue colora- 
tion indicating cobalt. If rosin is present, the procedure 
is slightly modified. 114 ce. of the thinned varnish is shaken 
with % ce. of ammonium sulpho cyanate solution; 14 ce. amy] 
alcohol, and from 3 to 4 ec. of ether are added. This mixture 
is shaken. As a red color might indicate a trace of iron, 1 
ec. of ammonium acetate solution and 2 or 3 drops of satu- 
rated solution of tartaric acid are added, whereby the var- 
nish-ether-amyl alcohol layer becomes green. The addition 
of 1 cc. of acetone causes a cobalt blue color to appear in the 
aqueous layer. The presence of lead and manganese does 
not interfere. 


* Robert S. Morrell, Varnishes and Their Components. Oxford Technical 
Publications. 


CHAPTER XVIII 


EXAMINATION AND ANALYSIS OF VARNISH RESINS* 


The value of a resin for varnish purposes depends largely 
upon its physical properties, such as color, hardness, and fusi- 
bility. In certain cases chemical tests, such as acid number 
and acetyl value, yield important information. Knowledge 
of the chemistry of the varnish resins, however, is far from 
complete and their composition, except in two or three cases, 1s 
not definitely known. Consequently there is much confusion 
in the literature regarding the proper method of procedure for 
determining the chemical constants. The purchase of resins 
on chemical constants such as iodine, saponification, and acid 
values together with ash, color, and size of lumps may not be 
far distant. Such procedure would at least eliminate many 
fanciful ‘‘gradings’’ now existing and which have but little 
meaning. 

All resins used in varnish making may, for analysis at least, 
be conveniently divided into two classes: 

(1) Fossil Resins (‘‘Copals’’ or ‘‘ Varnish Gums’’). These 
are in general very hard and difficultly soluble. They must be 
melted and held at a rather high temperature until a certain 
portion is driven off and they become soluble in oil. 

(2) Spirit soluble resins such as rosin, sandarac, mastic, 
damar, ete. 

These two groups interlap to a certain extent. For instance, 
Manila which is soluble in alcohol, must be ‘‘cracked’’ at a 
rather high temperature when used in oil varnishes and for 
the latter purpose might be considered as a fossil resin. 


PuysicaL CHARACTERISTICS OF Fosstu RESINS 

Hardness.—The term hardness is purely relative. More- 
over, the value of the resin depends not so much upon its initial 
hardness as upon the degree of hardness which it imparts to 
the finished varnish. <A resin of greatest initial hardness, 
however, usually produces the hardest varnish. The general 
scale of hardness of the principal types of copal, according 
to EK. J. Parry,t is as follows: 


*Arranged by the writer and P. C. Holdt, from Scientific Section, Cir- 
cular No. 159. ; 


yGums and Resins, E. J. Parry, Pitman & Sons, London. 


~— a 


Examination of Varnish Resins 


489 


1. Zanzibar 6. Sierra Leone (fossil) 11. Manila 

2, Mozambique 7. Yellow Benguela 12. White Myola 

3. Lindi 8. White Benguela 13. Kauri 

4, Benguela 9. Camaroon 14. Sierra Leone (liv- 
5. Pebble 10. Congo ing trees) 


15. South American 


This table agrees 
gators. 


fairly well with that of other investi- 


The hardness of resins may be measured by means of the 
methods described in chapter III. 


TABLE 64.—Table Showing Percentage of Resins Dissolved by Various 


Solvents. By Coffignier 

a # Carbon 

Ethyl Amyl Spirits of 2 

Alcohol Ether Alcohol | Turpentine ane p 

eet leo es Soe 14.10 | 25.00 | 36.70 | Insoluble Insoluble 
0 a 26.20 | 35.00 7P.60 39.70 15.00 
remneTOrA cw 27.90 | 44.60 | 47.00 7.50 24.50 
OS A 1421051" 61.70 97.80 31.80 30.90 
pierra leone. ........0-... 8/40 | 52.20 95.20 28 .60 29.10 
12 hs Sa 69.80 | 70.30 98 .20 51.80 55.10 
US Cl 83.50 | 56.30 99.10 31.20 26.00 
Rn oe... 42.60 | 57.40 91.50 20.40 30.10 
MeMCTUfig es SG es hoe ss 33.30 | 44.20 | 70.80 21.40 26.30 
ON 52.20 | 56.00 | 95.90 20.30 19.70 
GG 93.40 | 38.20 | Soluble 22.50 18.90 
oe 64.20 | 39.30 | Soluble 26.40 22.70 
OOS CO 87.70 | 52.70 | Soluble 27.10 28.10 
OO ONG 44.10 | 41.50 | Soluble 26.80 31.00 
Mienva, friable.........%. Soluble | 71.30 | Soluble 35.90 38 .00 
a Soluble | 54.00 | Soluble 33.60 38.09 
PievANPOlA. 6.2656... .. 84.90 | 72.70 98 .60 30.60 38.70 
PISO a. Se 62.40 | 48.70 | 93.00 23.00 22.30 
ees es ec. 83.00 | 50.00 | 95.10 31.30 30.40 


According to Bottler, resins may be tested for hardness by 
scratching with rock salt. All are seratched; the hardest 
only with much difficulty. He classifies them in order of 
decreasing hardness: 


1. Zanzibar 5. Congo 
2. Red Angola 6. Manila 
3. Sierra Leone 7. White Angola 
4. Benguela — 8. Kauri 


For further work on hardness of resins see page 499. 


Solubility.—The solubility of the various resins in different 
organic solvents has been thoroughly studied and numerous 
attempts made to develop a system of classification based on 


Examination of Varnish Resins 


490 


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Examination of Varnish Resins 491 
ee _.____..._— 
this property. The solubility of a particular resin varies with 
its age, handling after collection, etc. The hardest and best 
varieties are in general the most difficult soluble. Tables 65 and 
and 66 are taken from K. Dieterich’s ‘‘ Analysis of Resins.”’ 
For further results on solubility see pages 500 and 598-9. 


Fusibility—None of the resins have sharply defined melt- 
ing points. The fusing is a continuous process and may extend 
over a considerable range of temperature, as indicated in the 
table below. The harder resins require higher temperatures 
to melt them, and always undergo partial decomposition dur- 
ing the melting process. Different samples of the same kind 
of resin often differ considerably in this respect, hence the 
melting point is of little value in identifying a resin. 


TABLE 66.—According to Coffignier 


Specific Softening | Melting 

Gravity Point Point 
Re he ee ke we 1.058 at 16° 65° 165° 
ITEC, nec ee eee PoU5D at 7 45° 95° 
ERNE es ee hk es ee de 1.066 at 17° 90° 300° 
Ee Palys. oye et ee 1.061 at 17° 90° 195° 
Sierra eS, er 1.072 at 19° 60° 130° 
SI ee ee es Te OGG Ate ey ees oa Live 
UCM ys Ca svn os ee FO OOD Aes ace ee 150° 
EE A ee PeUsoratiey oto ee 120: 
Oa oe 1.065 at 17° 80° 190° 
0S ESN Sr 1.060 at 17° 45° 120° 
Nae SU SR 1.037 at 16° 55° 1352 
Se ee rh a eee a dng w bw eke ctw b Gt [eens ote eee? 100° 
ee eee ec bake cs Sis else dis ewte abana eke 

| 300 


Specific Gravity.—According to Bottler and Sabin,* specific 
eravity determinations are very useful in estimating the value 
of aresin. The specific gravity of the resin in its usual condi- 
tion and after being freed from contained air is found. The 
resins showing the smallest differences contain the least en- 
closed air and are assumed to be more valuable than their 
opposites. They find that Zanzibar, thus treated at 15° C., 
gives 1.0621 and 1.0636, the difference being 0.0015. Lindi 
copal shows a difference of 0.0010; red Angola 0.014; Cama- 
roon 0.015; Manila 0.059; and Kauri 0.064. 


*Bottler & Sabin, German and American Varnish Making. John Wiley & 
Sons. Pages 13-14. 


492 Examination of Varnish Resins 


A method for specific gravity suggested by Dieterich for 
rosin and which could be applied to other resins is as follows: 

A series of solutions of common salt, ranging between sp. 
gr. 1.070 and 1.085 at 15° C., are prepared, and in each of these 
is placed a few fragments of the colophony under examination, 
the temperature being maintained constant. The sp. gr. of 
the solution which retains the colophony in suspension will be 
the same as that of the substance. In selecting the test pieces, 
care must be taken to reject any which exhibit cracks, air bub- 
bles, or impurities. 


CHemicaL Examination or Fossit Resins 


Tschirech and his collaborators, KK. Dieterich and others, 
have done a great deal of work on the various resins and have 
collected much data concerning their composition, and chem- 
ical behavior. According to the majority of investigators, 
varnish resins consist largely of resin acids (resinolic acids) 
and neutral substances of unknown composition (designated 
resenes by Tschirch), with small proportions of volatile com- 
pounds, ash and impurities. The absence of esters, ethers, 
anhydrides and lactones (except in the case of rosin) has been 
fairly well established.* 

According to Tschirch and Stephen, the composition of Zan- 
zibar copal is as follows: trachylolie acid (Css6HssOs), 80 per 
cent; iso-trachylolic acid (CssHssOs), 4 per cent; essential oil, 
9.46 per cent; Alpha-resene (CsHesOs) and Beta-resene 
(C2HssO4), together 6 per cent; ash .12 per cent; impurities .42 
per cent. Congo copal, according to A. Engel} has the follow- 
ing composition: Congo Copalie Acid (C1sH3002) 48 to 50 per 
cent; Congo-Copalolie Acid (C22Hss04) 22 per cent; Alpha Con- 
go-Copal Resene, 5 to 6 per cent; Beta Congo Copal Resene, 
12 per cent; Ethereal Oil, 3 to 4 per cent; Impurities and Ash, 
4 to 9 per cent. 

For those resins which contain no other saponifiable com- 
pounds than the free resin acids, it might be expected that the 
acid number, determined in the usual manner (1. e., by dissolv- 
ing the resin in a suitable solvent and titrating directly with 
KOH solution) would be identical with the saponification num- 


re KE. J. Parry, contrary to most other workers, states that all copals contain 
esters. 
+ Journal American Chemical Society, 1903; Vol. 25, p. 860. 


Examination of Varnish Resins 493 


ber. This, however, is not found to be true in practice. The 
saponification number (indirect acid number) is usually con- 
siderably higher than the direct acid number. There are prob- 
ably several contributing causes for this variation. Accord- 
ing to evidence presented by Worstall* (in a very excellent 
article on Fossil Resins) when a resin is titrated directly with 
an alkali solution, the resin acids are neutralized very slowly. 
There are also indications that small amounts of aldehydes 
may be present and that these take up alkali during the saponi- 
fication process, thus giving a higher figure by this method. 

Numerous methods have been proposed for determining acid 
and saponification numbers using different solvents in varying 
proportions. Widely varying values have been reported, and 
much of the literature on the subject is highly contradictory. 
These differences of opinion are undoubtedly due in some 
eases to actual variations in the samples examined, many being 
of doubtful origin. In other cases where there is a wide 
divergence on apparently authentic samples of the same resin, 
it is probably due largely to a difference in the method em- 
ployed. Hence reported values are meaningless unless the 
method used is specifically described. 


Since many of the resins are insoluble or only partially solu- 
ble in alcohol, it is in general advisable to use other solvents. 
Various mixtures of alcohol, benzine, benzol, ether and chloro- 
form have been suggested. Alcohol alone is suitable only for 
rosin, shellac, and possibly Manila. 


The presence of water in the solution should be carefully 
avoided. It will not mix with most organic solvents, but forms 
an emulsion which makes the titration more difficult by render- 
ing the end point less distinct. Furthermore, according to 
Dieterich, the addition of water decomposes the resin soaps 
and results in abnormally high values. An alcoholic KOH 
solution should always be employed. 

The following methods of analysis have been used and found 
satisfactory by the writers: 


Direct Acid Number—Weigh three grams of powdered 
resin into a 500 cc. Erlenmeyer flask and add 200 ee. of alcohol 
benzol, Allow the mixture to stand overnight in a tightly 
stopped flask and then titrate with fifth normal alcoholic KOH 


*Archive der Pharmacie, 1908, p. 298. 


494 Examination of Varnish Resins 


solution, using phenol-phthalein indicator. Run a blank on 
the alcohol-benzol at the same time. 

Both the alcohol and the benzol used as solvents should be 
redistilled before using. The alcohol passing over at 78 to 
39° (. and the benzol at 80 to 82° C. being collected for the 
purpose. 

A fifth normal solution of KOH in C. P. absolute Methyl Al- 
cohol is used for both acid and saponification numbers. Methyl 
is preferable to Ethyl Alcohol on account of the difficulty in 
obtaining the latter sufficiently free from aldehydes to prevent 
darkening on standing. 

Saponification Number (Indirect Acid Number).—The same 
quantities of resin and solvent are used as in taking acid num- 
ber. An excess of alcoholic KOH is added, the flask tightly 
stoppered, allowed to stand 18 hours and then back-titrated 
with fifth normal sulphuric acid. <A blank is run on the same 
quantity of alkali and solvent as used in the determination. 

The saponification number may also be determined by boil- 
ing the resin-solvent-alkali mixture for 14 hour under a reflux 
condenser. The solution is cooled and the residual alkali. 
titrated as before. Saponification numbers determined in this 
way are somewhat higher than those determined by saponifica- 
tion in the cold. The solvents and alkali solution for saponi- 
fieation numbers are made up in the same manner as those 
used for Direct Acid Number. 

A method recommended by K. Dieterich and used by Wor- 
stall* with a slight modification in solvents gives very good 
results. This method is as follows: 

Weigh one gram of the finely powdered resin into a glass- 
stoppered bottle and add 15 ce. benzol and 5 ee. aleohol. Solu- 
tion is complete in a few minutes with these solvents. Then 
add 15 ce. fifth normal alcoholic potash solution and allow to 
stand 18 hours. Add 25 ec. alcohol and titrate the excess alkali 
with fifth normal sulphuric acid, using phenolphthalein as the 
indicator. Blank determinations are run each time. The addi- 
tion of alcohol before the titration is a great help in securing 
sharp end reactions. 


Acetyl Value——K. Dieterich proposed the following method 
for determining the acetyl value of resins: 


* Journal American Chemical Society, Vol. 25 (1903), page 862. 


Examination of Varnish Resins 495 


Boil the resin under a reflux condenser with an excess of 
acetic anhydride and a little anhydrous sodium acetate, until 
completely dissolved, or until it is evident that no farther 
portion will pass into solution. Pour the solution into water, 
collect the ensuing precipitate and extract with boiling water 
until perfectly oe from all traces of uncombined acetic acid. 
The insoluble residues left by copal and dammar are also 
treated in the same manner. The dried acetylized products 
are then tested for the acetyl, acid, ester and saponification 
values by dissolving 1 gram in cold Ate tell and titrating with 
half normal ne potash. The saponification is also Serie 
with half normal alkali for half an hour under a reflux con- 
denser, and the product titrated back after cooling and dilu- 
tion with alcohol (not water). As in the case of fate the dif- 
ference between the acetyl-saponification value and te acetyl- 
acid value gives the ‘‘true acetyl value.’’ 


Resins Other Than Fossil.— Under this heading are included 
the following types of resins: 


(1) Resins ordinarily used as solutions in some volatile sol- 
vent. Prominent in this group are shellac and macassar which 
are usually applied in alcohol solution and sandarac, mastic, 
and damar, which are generally cut in petroleum spirits. tur- 
pentine or some similar solvent.* 

(2) Rosin. 

(3) Ester Gum. 


(4) Synthetic resins. 


These resins are distinguished from the fossil resins in 
being softer, much more readily soluble in volatile solvents 
and having lower melting points. As indicated at the begin- 
ning of this chapter, however, there ig no sharp line of de- 
marcation between the classes. For example, both manila and 


macassar might be classed either as fossil or as aleohol soluble 
resins. 


Acid and saponification numbers can be determined by the 
Same methods as used for the fossil resins. While most of 
them are soluble to a certain extent in aleohol more concord- 
ant results will, in general, be obtained when the resin is dis- 


*Manila might also be placed in this class as it is soluble in alcohol and 
is frequently so used. 


496 Examination of Varnish Resins 


solved in a mixture of alcohol and benzol.* Alcohol alone is 
entirely suitable as a solvent only for rosin, shellac and ma- 
cassar. 


Macassar, Sandarac, Mastic and Damar.—These resins are 
usually evaluated entirely on a basis of color, solubility, size of 
lumps and freedom from dirt or other foreign material. How- 
ever, chemical tests such as the determination of acid number 
are of value in checking up on the uniformity of different 
shipments. 

Shellac (see Chapter X XIX). 


Ester Gum.—The main consideration in the evaluation of 
ester gum is, as a rule to secure the lowest possible acid num- 
ber consistent with good color. Determination of melting point 
and the degree of darkening occurring during melting are 
also important indications of quality. 


Ethyl Acetate Test for Ester Gum.—One part ester gum 
is dissolved in 1 part of ethyl acétate. The solution is placed 
in the ice box at 0° C. for 72 hours. At the end of that time 
there should be no precipitate in the vessel. It has been sug- 
vested by one resin manufacturer that any matter precipitated 
in this test decreases the adhesive properties, diminishes the 
gloss and hastens the decay of lacquers and varnishes using 
ester gum which contains it. 


Yacca Gum (Red Gum; Gum Accroiides)—This product 
which is quite widely used as a shellac substitute in dark 
colored compositions, is almost entirely insoluble in benzol, 
mineral spirits, or turpentine. It is readily soluble in acetone, 
ether, and alcohol. Distillation under vacuo generally yields 
a phenol body having a strong phenol odor. For methods of 
testing shellac see page 526. 


Phenolic Type Resins.—Resins of the formaldehyde-phen- 
olic type are readily identified by their strong odor of cresylic 
acid or phenol. Fonrobert (Chem. Ztg., 1922, 46,513) de- 
scribes the results of tests made on a series of condensation 
products from various German sources. A study of these 
results shows the great variety existing In many German 
products. Steinitzer (AKunststoffe, 1915, 5,109) states that 
the phenol resins may be detected by boiling with caustic soda 


*Sandarac is practically insoluble in benzol. For analytical purposes hot 
absolute alcohol is the best solvent. 


Vi 
5 


< 


Examination of Varnish Resins 497 


solution or heated soda-lhme, when phenol is liberated, which 
may be identified by odor or color reactions. This method 
would hardly serve to discriminate between phenol-formalde- 
hyde condensation resins and other resins of a phenolic nature. 
Redman, Weith, and Brock (J. J. E. C., 1914, 205) gives a 
method for the determination of phenol in the presence of 
hexamethylenetetramine and formaldehyde. 

An improvement on Steinitzer’s method has been proposed 
by Herzog. He observed that the quantity of phenol liberated 
by the Steinitzer test was small and obtained better results by 
distilling the powdered sample in a current of nitrogen. 
Filings of the sample are sifted to yield a fine powder. The 
latter is placed in a distilling flask with a long side outlet tube. 
The side tube is bent at right angles so as to extend nearly to 
the bottom of an Erlenmeyer flask. A current of nitrogen is 
passed through the distilling flask. By this method, Herzog 
claims to have recovered phenol equivalent to 4 of the sample. 


A method for the determination of free phenol in synthetic 
phenolic resins has also been suggested by Morgon and Meig- 
han (J. J. E. C., 1925, 17, 626). This depends on the meas- 
urement of the hydrogen evolved after treating with sodium, 
the phenolic solution produced by extracting the resin with a 
solvent. 


Coumarone Resins.—Coumarone resins, according to Mar- 
eusson (Chem. Zeit., 1919, 48, 109 and 122) dissolves com- 
pletely or almost completely in acetone, while coal tar pitch, 
lignite pitch, wood-tar pitch, and petroleum pitch are practi- 
eally insoluble in this solvent. 

Wolff’s method (Farben Ztg., 1918, 23, 307) for the identifi- 
eation of coumarone resins has been developed and success- 
fully used by Ellis (‘‘Synthetic Resins and their Plastics,’’ 
1925, p. 54). The separation from fatty acids is accomplished 
by saponification, the soaps being separated by boiling with 
water. ‘The final identification of the resin is made by destruc- 
tive distillation. Coumarone resin decomposes at 300-400° 
into coumarone, b. p. 172, indene b. p. 182, hydrindene b. p. 
176, along with a small quantity of cresols. The presence of 
coumarone and indene in the distillates is determined by means 
of their picrates and bromides; coumarone picrate melts at 
102° C. and the dibromide at 86° C. Indene picrate boils at 
180° C., while the dibromide melts at 43-45° C. 


498 Examination of Varnish Resins 

A more rapid method of determining coumarone in resin 
is by the color reaction with bromine. Coumarone resins give 
a permanently red color when treated with bromine in the 
presence of glacial acetic acid. The test is carried out as 
follows: 1 cc. of a 10% solution of the resin in chloroform is 
diluted with 6 ec. of chloroform, and 1 ce. of glacial acetic 
acid is added. The solution is then shaken and 1 ce. of a 107% 
solution of bromine in chloroform is added, the solution again 
shaken, and allowed to stand. A permanent red color devel- 
ops if coumarone resin is present. 


During the last few years many synthetic resins have come 
into the varnish and lacquer trades. Some have been made 
from glycerol and phthalic anhydride, and by condensation 
reactions with toluol products. Probably the most important 
class is represented by the Albertol resins produced through 
reactions between phenol and formaldehyde, usually in the 
presence of some rosin. This latter type is differentiated 
from the Bakelite type of phenol resins by their hardening 
properties in the absence of baking, as well as their solubility 


i 
\ 
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re. 
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in oils. The identification of these resins is naturally a diff- . : 


cult matter. A determination of their physical constants 
gives much more information. 


Testing the Physical Properties and Solubility of Some 
Synthetic Resins —Some of the synthetic resins of the modi- 
fied phenol-formaldehyde type, which have recently appeared 
upon the market are being used to a considerable extent in 
the production of quick drying varnishes. The main char- 
acteristic of these resins is the harder surfaces which they 
produce. This was clearly shown by exposures of exterior spar 
varnishes made with one of these resins, as compared to a 
similar varnish made with ester gum. They were applied in 
thick, flow-coat films to metal panels and exposed upon the 
roof of the laboratory. The varnish made with the synthetic 
resins apparently dried to a hard film, whereas those made 
with ester gum apparently dried only at the surface, the under 
portion remaining soft. This condition naturally caused the 
formation of cracking and checking. 


The melting point, acidity, and hardness of these synthetic 
resins as compared with rosin and ester gum are given in the 
table below. In determining the hardness of these resins, they 
were fused and poured into friction top can lids to a depth 


499 


Examination of Varnish Resins 


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Examination of Varnish Resins 


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Examination of Varnish Resins 501 


of about 3/16 inch. Upon cooling, the determination of hard- 
ness was made with a swinging beam, in accordance with the 
outline given on page 74. This method, of course, is subject 
to improvement. 

The solubility of the synthetic resins referred to above was 
determined, and is given in Table 68. Determination was 
made by adding an excess of resin to the solvent, and heating 
the mixture. Upon cooling, the clear mixture was removed 
from the suspended matter, a portion weighed and evaporated, 
and the amount of non-volatile thus determined. This gave 
information as to the amount of resin that could be held in 
solution by any of the solvents used, at a temperature of 20 
to 20 degrees C. Wherever the figure 100+ is given, it indi- 
cates that the solvent referred to will hold in solution, at the 
temperature given, at least 100 per cent of the resin experi- 
mented with. 


502 Examination of Varnish Resins 


EXPOSURE TESTS ON RESINS 
SERIES A. 
RESIN SOLUTIONS. 


50 parts by weight Resin, 50 parts by weight Toluol (or other solvent noted.) 
Panels exposed Feb. 24, 1927. 


Rating on 
April8 May 24 General Observations 

ae a nnn neces 

Fine checking in 1 month. Heavy 

Ampberol “BiSsli.is% te 5 4 chalking and loss of gloss after 3 
months. 

Fine checking in 1 month. Heavy 

Amberol: 7.5.05. 535% 4 4 chalking and loss of gloss after 3 
months. 

. Chalking after 1 month. Rusts through 

Amberol: HAO. 0s 25 ewe see 5 2 film in 2 monte 
Some loss of gloss and slight chalking 
Condensation No. 1...... 10 8 after 2 months. Film checked but 


no rust after 3 months. 
Entire surface covered with rust in 5 


1 s » ‘ 
Condensation No. 2...... 0 0 days. Failed. 
‘ CS Chalking and fine checking in 6 weeks. 
Ran CONnZO.s Pes eee 5 a Rust under film’ in 12 weeks. 
AS : Chalking after 4 weeks. Very heavy 
Tadeht Cumays.. 5:08 ate + 4 chalking at end of 12 weeks. 
‘ : Rust through film in 5 weeks. Covered 
Damar Batavia......... 4 2 with rust in 12 weelee 
Damar Singapore (alco- Ghalking in 8 weeks. Heavy rust under 
DOLD-A4 soe Wee oe age 8 4 film but film intact after 12 weeks. 
Retar (1 Fine checking and chalking in 4 weeks, 
i ee leet Be A Since 2 2 Rusts through film in 12 weeks. 
Hexol G (2 resin—1 - Fine checking in 5 weeks. Some rust 
toluol—1 alcohol) .... 10 vé through film in 12 weeks. 
Alligatoring and chalking after 4 weeks. 
Hesol) R-205¢6 sa wees eee 1 0 Rusts through film after 12 weeks. 
Failed. 
j Fine checking and chalking after 4 
Rey vs fal Secs ake ee 3 1 weeks. Rusts through film after 12 
weeks. 
Chalking after 4 weeks. Rust under 
Manila “(Caleonol j-3..<.4.< 3 2 film and heavy chalking at end of 
12 weeks. 
Fine checking and chalking after 4 
Pontianak (alcohol) ... 3 1 weeks. Rust through film in 12 
weeks. 
Fine checking, slight chalking after 4 
Rosin (Refined Wood) .. 3 1 weeks. Rusts through film in 12 
weeks. 
Fine checking, slight chalking after 4 
Rosin (W.W Gum Rosin) 3 0 weeks. Rusts through film in 12 


weeks. Failed. 


0 Fine checking but fair gloss in 4 weeks. 


tlycerol-Phthali Si 
Glycero halide Resin 2 Rusts through film in 6 weeks. Failed. 


SR ee ERC ee Me ee SOR Ne ce eg Aebeerjceg een niimeniiaill 9 


Examination of Varnish Resins 503 
— 
SERIES B. 


RESIN AND OIL SOLUTIONS. 
Resin solutions of Series A extended with oil. Oil used was heavy bodied 
linseed oil dissolved in an equal volume of toluol. 5 parts of 
resin solution A and 1 part of oil solution. 
Panels exposed Feb. 24, 1927. 


Rating on 
April8 May 24 General Observations 
Fine checking in 4 weeks. Rust under 
mE werot bs, 1 ..e sk... 8 6- film in 6 weeks. Rust under film in 
12 weeks. 
Binverag, N-f ........... 9 7* Checking. Some rust. Dull in 6 weeks. 
oe - 2S 0 gq Heavy chalking and some’ rust through 


film in 4 weeks. Failed. 


‘ c hilm intact. Rust in oil craters after 
Condensation No. 1 ..... 8 tf toeweeks 
PGienvation No. 2 7 5 Slight rust under film after 8 weeks. 


Film sound after 12 weeks. 


Slight chalking after 4 weeks. Heavy 
PUT ONLO So... ks eae bi) ae chalking but film fairly sound after 
12 weeks. 
Slight chalking after 6 weeks. Heavy 
ate ADUINGY os oe es ss 5 D chalking but film fairly sound after 
12 weeks. Dark color. 


Fine checking in 4 weeks. Heavy 


‘ chalking and rust under film in 8 
Damar Batavia ......... 8 2 weeks. Rusts through film in 12 
weeks. 
Fine checking in 4 weeks. Heavy 
Damar Singapore (alco- chalking and rust under film in 8 
US 8 2 weeks. Rusts through film in -12 
weeks. 
Covered with fine checking after 4 
Oo ET rrr o 0 weeks. Heavy chalking and rusts 
through film in 8 weeks. Failed. 
Hexol G (2 resin—1 Chalking and some rust under film in 
toluol—1 alcohol) .....10 7 12 weeks. Film sound: 
Chalking after 4 weeks. Rust under 
OO 0 0 film in 6 weeks. Rusts through film 
in 12 weeks. Failed. 
Fine checking and chalking in 4 weeks. 
OS 0 0 Rust under film in 8 weeks. Rusts 
through film in 12 weeks. Failed. 
; Fine checking and chalking after 4 
Manila (alcohol) ....... 4 3 weeks. Rust under film after 6 weeks. 
Fine checking and chalking after 4 
Pontianak (alcohol) .... 3 0 weeks. Slight cracking and rust 


under film after 8 weeks. Rusts 

through film after 12 weeks. Ki 
Checking, chalking and rusting after 4 
Rosin (Refined Wood) .. 0 0 weeks. Rusts through film after 6 
weeks. Failed. 


Checking, ‘chalking and rusting after 4 


Rosin (W.W.Gum Rosin) 0 0 weeks. Rusts through film. after 6 
weeks. Failed. 
Glycerol-Phthalide Resin 7 9 Checking but fair gloss after 4 weeks. 


Rusts through film in 6 weeks. 
* Pitted in spots where separation occurred. 


504 Examination of Varnish Resins 
hetoell eae nme ecnieieaneniriae Cia MR 


SERIES C. 


LACQUER-RESIN SOLUTION, 


A standard lacquer base was made of 100 parts by weight of 32 oz. Butyl 

Acetate Solution of 1% second Nitrocellulose, 50 parts by weight of toluol, 

and 5 parts by weight of tricresyl phosphate. To 155 grams of this solution, 

GO grams of resin solution, such as were used in Series A, were added. 
Panels exposed Feb. 24, 1927. 


Rating on 


April8 May 24 


AMDGPOLIE Se kote oe ee 7 
Amberol F-71703 Guacasae 8 
Amberol HeO 4.27 7h wise re 
Condensation No. 1 ..... 9 
Condensation No. 2 ..... 9 
Ran One 0 en soo wie aes 7 
Light Comarces 5...) wines +) 
Damar Batavia ....... 10 


Damar Singapore (alco- 


TG] peas wee ect ae 10 
Ester Gut wasscc owiehe Z 
Hexol G (2 resin—1 

toluol—1 alechol) .... 10 
Hevolh Ress oe ce ee 0 
Rin RAWels. oes eee 3 
Manila: (aleonol) =... 5.6 4 


Pontianak (alcohol) .... 5 


Rosin (Refined Wood) .. 90 
Rosin (W.W. Gum Resin) 0 


Glycerol—Phthalide Resin § 


3 


4 


0 


° 


General Observations 


Slight spotting and rust under film 
after 4 weeks. Rust through film 
after 8 weeks. 

Slight spotting and rust under film 
after 4 weeks. Rust under film but 
film still sound after 8 weeks. 

Spotting and rust under film after 4 
weeks. Rust through film after 8 
weeks. 


Rusts through film after 12 weeks. 


Rust under crystals in 4 weeks. Rusts 
through film in 12 weeks. 

White spots on surface and rust under 
film after 4 weeks. Rusts through 
film after 6 weeks. 


Rust under film after 4 weeks. Heavy 
chalking but film sound after 12 
weeks. Dark color. 


Slight rust under film in 6 weeks. 
Peeling after 8 weeks. Covered with 
rust after 12 weeks. Failed. 

Slight rust under film in 6 weeks. 
Peeling after 8 weeks. Covered with 
rust after 12 weeks. Failed. 

Rusting under film after 4 weeks. 
Heavy chalking and rust through film 
in 8 weeks. Failed. 

Rusting under film after 4 weeks. 
Heavy chalking and rust through 
film in 8 weeks. Failed. 

Film failed at the end of 4 weeks. 

Slight rust under film after 4 weeks. 
Heavy rust under film, heavy chalk- 
ing, but film intact after 12 weeks. 

Rust accumulating under film after 4 
weeks, which finally breaks through 
film after 12 weeks. 

Rust accumulating under film after 4 
weeks. Rust breaks through film 
after 12 weeks. Failed. 

Rust through film after 4 weeks. 
Failed. 

Rust through film after 4 weeks. 
Failed. 

Film peeling after 6 weeks. Rusts 
through film after 8 weeks. Failed. 


505 


h Resins 


Is 


Examination of Varn 


‘SSO[S pooyy ‘“SulyVp iy SIS 
*suUIYIIYI IQ BIBPISHOD— Uo puo0g 


SAV LT YADAV 
Gua TIVA UANOOVT NI NISAY 


PST quo oLy 
‘SSO[S POOK) “SuTypaqo deeq—wuorrpuog 


‘SAVC L YUALAV GAAIIVA TIO 
HLIM GHAONHLXG HSINUVA LIYIds 


NISGY HAlTIVHLHd-IOUROATD 


‘SSOIS pooy “Wy MOTaq 
ISNI V[CBIIPISUOD = “payooyO—'uoripuog 


‘SAV 6 YALAV 
daa TIVa HSINUVA LIvIds 


ish Resins 


Examina 


506 


tion of Varn 


[BJU 
oq} 0} SuLeypB I]S WY Jo sJususeAy IB] 
-NSUBII] [TRUS [JIM paleAod SUTEq sDUBlTVq 
ay} “BaIv 9} J[BY-9UO IBAO [BJO V1Bq SUT 
-Ave] ‘pojdnastp A[peq WIly—wo1z7puog 


‘SAV LI UALAV 
GW1IVA WANOOVI NI NISGUY 


fe > Sera OT I OR ee 


GOT ANAT 


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‘SyooyO OUTT[BISAIO YJLAK PoovpAojUL ATOITUa =-[B}JSL1O UY AIOA YITA PodBIAL9}UT Ajaarjue 


WIJ WNI ON ‘sso[s pooy—uolipuoyg WITT ‘ySsSnt ON ‘[[NpP vovjang—woripuog 
‘SAV 8 MALAV GATIIVA TIO ‘SAVC LT YALAV 
HLIM GQHANULXH HSINYVA LIUIds GaWTIVA HSINUVA CINIds 


VIAVLIVd UVNNVAd 


507 


f Varnish Resins 


Examination o 


‘sjyutod poqyesailses UT 
Wy POsteI JO SUOTIIS AB[NSUBII] SUTIABVT 
‘TBjou Woy AVMB PoTBos AT[RIARd pue 
pexyoseqo Alpeq AatoA UWYLy—woirpuog 


‘SAV OT UADCAV 
GaTIVa YANOOVI NI NISAUY 


OST aNOdIA 


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Io[od Joque snbedo Ue potinsse sey wy 
PpoyV,T “SULp~IYyO PadVl[19JUL YIM pod1dAood 
AjoItjUe WII] ‘“Sso[s ALB Y_——wolpuog 


‘SAVG L YALAV GH TIVA TIO 
HLIM GQHAUNHOXH ASINUVA LIYIdS 


‘UISOL 
jo sjTejshao OJUT PoIdnAsIp WIT ‘syooyo 
oug YIM PIIIAOD sdvJINg—uUoOIIpUoy 


‘SAV OT UALAV 
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WAS YUALSa 


ish Resins 


f Varn 


10n oO 


rs 


Examina 


508 


yw 5 al Pad + ree == ha, + Ve - 


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poos A[aAVjei Ul 818 SReIe Surpuno.sins 
YABC “LOTOO JUST] JO 91B YOIYM pue onbdoeyT 
woody Uns JO uoTyVaedas oyIT Teedde ory 
suotjdniia podeys-asesnes pue [eotreyds 
I[BUIS YIIM pPd19AOD VdBJANg—wUOWMpUOY 


‘SAV OT UADAV 
aW11VA YUANOOVI NI NISAY 


ae a fi ee. OD ee — 


IST auooLT 


‘SULYOIYO PaR[A9}UT ou AII A 


“‘SULyOeYO 
‘OBJANS IDAO [[B Sjods v}ITA—wolppuog 


SIG “SuryreyD ‘Tup 419a4A—wowrpuog 


‘SAV 16 YALAV 
awWiiIVa HSINYVA LIYIds 


‘SAV Le UALAV GWTIVA TIO 
HLIM GQHONGULXH AHSINUVA LIYIds 


VTIINVIN 


Examination of Varnish Resins 509 


CRYSTALLIZING CONDENSATION RESIN INC) 


SPIRIT VARNISH EXTENDED WITH RESIN LACQUER FAILED 
OIL FAILED AFTER 18 DAYS. AFTER 16 DAYS. 


Condition.—Surface covered with raised Condition.—Surface covered with needle 


spherical masses of white crystals in con- shaped crystals radiating out from erystal- 
trast with dark background of metal. lizing points. 


FIGURE 188 


RUN CONGO 


SPIRIT VARNISH FAILED SPIRIT VARNISH EXTENDED WITH 
AFTER 4 DAYS. OIL FAILED AFTER 4 DAYS. 
Condition.—Film covered with what ap- Condition.—Surface checking of a broad 


pears to be raised surfaces in the form order shown. Line in photomicrograph is 


of hexagonal checks. Very slight rust. one side of a check. Fair gloss. 
Good gloss. 


FIGURE 189 


510 Examination of Varnish Resins 
OS 
Color Comparison of Resins.—For comparing the color of 
rosin. there is available a set of standard color cubes which 
may be obtained from Harris N. King, Naval Stores Inspec- 
tor, Savannah, Ga. It is believed the price is about es 00. A 


FIGuRE 190 


Apparatus Used by Pfister in Making Resin Standards. 


method of making standards of a somewhat different char- 
acter, for comparing the color of various resins, has recently 
been evolved by K. Pfister* who has forwarded the following 
description of his method: 

Various methods have been proposed for measuring the 
depth of color of resins, e. g., the use of standardized solutions 
of Potassium Chromate and Bichromate, solutions of Iodine 
in Potassium Iodide, ete. These methods are in general satis- 
factory and allow of a comparatively accurate measurement 


Examination of Varnish Resins 511 


in terms of numerical scales, and we have found the use of 
such methods essential where small differences in color must 
be accurately measured. 


It was also necessary, for our purpose, to be able to measure 
the color of resins in terms of some widely recognized scale, 
and by a method the technique of which should be relatively 
simple. The Standard Rosin Types, although they admittedly 
possess defects for this purpose, naturally suggested them- 
selves, on account of their wide recognition, as the most suit- 
able scale. The method employed for making comparisons 
is as follows: 


Fight gms. of the sample of resin, in small pieces, is placed 
in an inverted Aluminum screw cap, as supplied with the 
standard 4 oz. friction top bottle, and the cap placed on a wire 
gauze ona tripod. A piece of wide glass tubing is fitted into 
the serew cap so as to form a funnel and a stream of CO2 run 
in. The sample is then melted with a Bunsen flame until it has 
fused to a clear mass. It is allowed to cool in an atmosphere 
of COz, until the Aluminum ean just be handled. The base of 
the screw cap is then removed by filing the edges with a steel 
file. This leaves a transparent circular disc of resin of con- 
venient and uniform thickness. By removing the base, as sug- 
gested, before it has completely cooled, shattering of the dise 
is avoided. The disc can then be compared with similar discs 
prepared from Standard Rosin Types. By placing two discs 
alongside each other over white paper and by examining by 
transmitted light, satisfactorily accurate comparisons can be 
made. Considerably more accurate comparisons can be made 
with these discs than with the cubes prescribed for the official 
Rosin Types. 


Toluol Insoluble Clarity Test for Rosin.—Methods for the 
determination of the clarity of rosin (freedom from dirt, 
wood chips, bark, ete.) have been studied by a special com- 
mittee of Committee D-1 of the A. S. T. M. These methods 
have been investigated in this laboratory and in other labora- 
tories with results which check very closely, and have been 
recommended for adoption by the Society. They are pre- 
sented below: 


Laboratory Handling of Sample.—Immediately before the 
determination is to be made, powder the sample to pass a 10- 


512 Examination of Varnish Resins 


mesh sieve, mix thoroughly, and place in a wide-mouth bottle 
which is filled thereby. 


Determination.—Place 50 grams of the freshly powdered 
sample in a 300 ee. beaker and add 150 ce. of toluol, free from 
water and non-volatile residue. Dissolve the sample with the 
aid of heat and occasional shaking. When solution is appar- 
ently complete (no particles of rosin visible) filter at once 
through a 25 ce. porcelain Gooch crucible which has been 
previously prepared with a mat of pure well-washed asbestos 
such as is used for the determination of BaSO,, and which has 
been finally washed thoroughly with the solvent used, dried in 
a boiling water oven for % hour, cooled in a dessicator and 
weighed. If the rosin filtrate is not clear return it through 
the Gooch until clear, finally washing the residue and the 
outside of the crucible free from rosin with additional hot 
solvent. Dry to constant weight at 105-110° C. (one hour 
usually suffices), cool in a dessicator, weigh, and calculate the 
percentage of toluol insoluble. 


Softening and Melting Points of Rosin.—Satisfactory meth-, 
ods of determining the softening and melting ;points of 
rosin have been studied by a special committee of Commit- 
tee D-1 of the A. S. T. M. As yet, these methods have not 
been adopted. In this laboratory they have given in general, 
excellent results. They are presented below, merely as a 
matter of general interest and to stimulate further work in 
this direction. 


DEFINITIONS 


Softening Point.—The temperature at which powdered rosin 
in a melting point tube begins to darken and coalesce. 

Melting Point.—The temperature at which powdered rosin 
in a melting point tube loses its powdered or crystalline shape 
and becomes wholly transparent. 


APPARATUS 


Thermometers must be accurate, graduated in degrees Cen- 
tigrade from 45 to 100 and have a length of about 5% inches 
(137 mm.) and diameter of about 44 inch (6 mm.). 


Test Tubes % by 6 inches (18 by 150 mm.) are fitted with 
eorks grooved at sides to permit air circulation and bored at 
center to receive thermometer. 


Melting Point Tubes of thin glass, inside diameter 1/16 
inch.(1.5 mm.), length about. 2 inches (50 mm.) and closed 
at one end. 


Examination of Varnish Resins 513 


Flasks are ordinary Erlenmeyer type of 300 cc. capacity, 
the mouths of which must be at least 1 inch (25 mm.) diameter 
and fitted with a cork grooved at sides to permit air circula- 
tion and bored at center to receive test tube. 


DETERMINATION 


Place 250 ec. glycerine in the flask, insert the grooved cork 
earrying test tube so that its lowest point is % inch above 
the bottom of the flask and heat the flask so that the ther- 
mometer rises at the rate of 1° C. per minute. 

From the freshly broken surface of a lump of the rosin 
quickly powder a sample (1-2 grams) and at once fill 4 melt- 
ing point tubes to a depth of about 10 mm. lightly packing 
with a fine glass rod or by tapping. Pass the stem of the 
thermometer through a cork, grooved to permit air circulation. 
Attach two of the filled melting point tubes to the thermom- 
eter so that the rosin is opposite the bulb. When the tem- 
perature of the glycerine in the flask reaches 45° (. place the 

-thermometer and m. p. tubes in the test tube so that the bottom 
of bulb is % inch above the bottom of the test tube. Continue 
to heat the flask at the rate of 1° C. per minute, note and re- 
cord the temperature at which the rosin begins to darken and 
coalesce (softening point) and also the temperature at which 
the rosin loses its powdered or crystalline appearance and be- 
comes wholly transparent (melting point). It is necessary 
during a test to have a light behind the flask, daylight or 
electric light. Repeat the test, using the other two filled melt- 
ing point tubes, making sure that the glycerine bath is below 
49° C. at the start. 

The four tests of melting point must not vary more than 1° 
C., otherwise two additional tests must be made and the aver- 
age reported. The softening point tests will probably vary 
more than the melting point tests. Report the average of 
each set of results as the softening point and melting point 
respectively. 


Some results on samples of rosin as obtained at this labora- 
tory by the above methods, are given below: 


OE, o. sc once svc en conv cieway 00°C d9°C 
57 58 
54 59 
53 57 
56 
60 
Mean 55°C 58°C 


514 Examination of Varnish Resins 


Melting Point 2, ...ceccccnsesssecscesercs 63.0 68 
62.0 «64 

62.0 65 

62.5 64 

63 

65 

Mean 62.5 65 


Drip Method for Melting Point of Rosin——Another method 
experimented with by the committee was the drip method. 
This is outlined below. The drip method will probably give 
results in various laboratories which will check closely, but 
the results are usually about 15° higher than by the capillary 


method. 
DEFINITION 


Melting Point.—The temperature at which the elongated 
drop of rosin from the thermometer bulb touches the bottom 
of the test tube. 


APPARATUS 


Thermometers.—Use an A. 8. T. M. Flash Test Thermom- - 
eter. Range —5° to +110° C. Total length 277-282 mm. 
Bulb length 9-13 mm., bulb diameter not greater than 6-7 mm. 

Test Tubes.—22 x 180-200 mm. fitted with corks grooved at 
sides to permit air circulation and bored at center to receive 
the thermometer. | 

Beakers.—Low or ordinary 600 ee. beaker. 


DETERMINATION 


From the freshly broken surface of the rosin remove a 
sufficient quantity to fill an 18 mm. diameter test tube to a 
depth of about 40 mm. Place the test tube in a boiling water 
bath until the rosin becomes fluid enough to adhere in a film 
on the thermometer. Heat the previously weighed thermom- 
eter to 100° C. by immersion in a bath of boiling water, 
quickly wipe dry, and dip into the rosin to a depth of 15 mm. 
from bottom of bulb, securing a coating which weighs when 
eold .50 to .55 gm. and is uniformly distributed. It will prob- 
ably be necessary to shape the rosin with the fingers. Cool 
the film rapidly, taking care that it remains evenly distributed, 
and allow to rest 10 minutes after cooling to room tempera- 
ture. Fill the beaker to a depth of 90 mm. with water at 
not over 45° C. Pass the thermometer through the cork and 
insert in the test tube so that the bottom of the bulb is 25 mm. 
above the bottom of the test tube. Fix the test tube in the 


Examination of Varnish Resins 515 


beaker of water so that the lowest point of the test tube is 
25 mm. above the bottom of the beaker. Heat the water 
so that the thermometer rises at not more than 2° (. per 
minute up to 65° C. and at a rate of 1° C. per minute above 
65° C. The average temperature in 4 tests at which the 
rosin dropping from the bulb of the thermometer touches the 
bottom of the test tube is recorded as the melting pomt (drip 
method). Ifthe variation of the 4 determinations is greater 
than 1° C. an additional determination shall be made and the 
average of the five determinations reported as the melting | 
point (drip method). 


CHAPTER XXIX 


SHELLAC ANALYSIS 


Many developments in connection with the analysis and 
testing of shellac have taken place during the past three years. 
Committees of experts representing importers and consumers 
have now arrived at specifications which have been adopted 
by the A. S. T. M. These specifications are presented below, 
including methods of test covering the raw material and shel- 
lac varnishes. Following these, there is presented the Steele 
modification of the McIlhiney method for the determination 
and estimation of adulterants in shellac varnish. This meth- 
od, which has been used at this laboratory for several years, 
is fairly rapid and has proved useful. Information is also 
presented on a method of determining the darkening of cut 
shellac. 


A. 8. T. M. STANDARD SPECIFICATIONS FOR 
ORANGE SHELLAC 


1. Orange shellacs may, for convenience, be grouped into the four follow- 
ing grades: Grade A, Grade B, Grade C and Grade D. Stick, seed, garnet 
and button lacs are not included under these grades. 


I. PROPERTIES 
2. Orange shellac shall conform to the following requirements: 


GRADE A GRADE B GRADE C GRADE D 


Iodine number, maximum...........+.- 18.0 18.0 18.0 24.3 
Matter insoluble in hot 95-per-cent alco- 

hol, maximum per cent...........+ 1.75 2.50 3.00 3.00 
Moisture and volatile matter, maximum, 

per. Cent Waal ae. ees ee 2.0 2.0 2.0 BY 
Matter soluble in water, maximum per 

CONC vs CLEA heats ee ron ae nes 0.5 0.5 0.5 0.5 
Wax, maximum, per cent.............- 5.0 5.5 5.5 5.5 
Ash, maximum, per cent.........0+-+++ 1.0 1.0 1.0 1.0 


II. SAMPLING 

3. (a) Only original packages shall be sampled. 

(b) Samples-shall be drawn by hand, or a suitable tryer may be used, pref- 
erably from not less than 10 per cent of the lot. 

(c) In sampling “free” shellac, approximately double handfuls shall be 
drawn from each bag and quartered down to approximately 2 lb. The shellac 
shall then be ground to pass through a No. 20 sieve (840 micron opening), half 
of which shall be reserved by the buyer, the other half used for analysis. 

(d) In sampling “blocky” or “matted” (hard) shellac, about 1 Ib. from 
each bag sampled shall be ground to pass a j-in. sieve. This shall then be 


Shellac Analysis 517 


quartered down to approximately a 2-lb. sample which shall be ground to pass 
through a No. 20 sieve (840 micron opening) and divided as in sampling 
“free” shellac.* 


III. METHODS OF TESTING 

4. The determination of iodine number, matter insoluble in hot alcohol, 
moisture and wax shall be made in accordance with the Standard Methods 
of Testing Shellac (Serial Designation: D 29) of the American Society for 
Testing Materials,y and the Standard Method of Test for Determination of 

5. The determination of matter soluble in water shall be made as follows: 

Weigh 10 to 25 g. of the sample accurately and stir thoroughly with 100 ce. 
of distilled water in a suitably sized flask or beaker. Cover with a watch glass 
and allow to stand at room temperature (approximately 21°C.) for four 
hours, stirring occasionally. Decant the water through a 12.5-cm. filter paper 
into a weighed evaporating dish, washing the shellac and paper with at least 
50 cc. more of water. Hvaporate the water and dry the extract at 105 to 
110° C. for one hour or more to constant weight. Cool, weigh, and calculate 
the percentage of matter soluble in water. 

6. The determination of ash shall be made as follows: 

Approximately 2 to 3 g. of the sample shall be accurately weighed, trans- 
ferred to a weighed porcelain or platinum crucible and ignited at as low a 
temperature as possible until all organic matter has been destroyed. The 
crucible and contents shall be cooled and weighed and the percentage of 
ash calculated. 


EXPLANATORY NOTES 

In general, Grade A will include grades of shellac known in the trade as 
D.C., VSO, Diamond I, Double Triangle G and Superfine. 

In general, Grade B will include the grades known in the trade as Fine, 
Good and Heart Brands. 

Grade C represents the grade known in the trade as Pure TN. 

Grade D represents the grade known in the trade as U.S.S.A. TN, and 
which may contain up to 3 per cent of rosin. 


A.§8. T. M. STANDARD METHODS OF TESTING SHELLAC 
DETERMINATION OF MATTER INSOLUBLE IN HOT ALCOHOL 


(a) Continuous Extraction Method (suitable for all grades of lac.) 


APPARATUS 
1. The extraction apparatus (Fig. 191) shall consist of a wide-neck flask in 
which is suspended a metal return condenser. From the lower part of this 
condenser is hung a siphon tube of Knoefler type. The extraction cartridge 
used for the determination shall be cut down to such a size that the top of 


*The above is a brief abstract of the Rules and Regulations of the United 
States Shellac Importers Association. 

71924 Book of A.S.T.M. Standards. 
Wax in Shellac (Serial Designation: D 29) of the American Society for 
Testing Materials. 

¢A.8.T.M. Standards Adopted in 1925. 


518 Shellac Analysis 


the cartridge is just above the upper curve of the siphon. It shall be supported 
on three indentations in the glass so that there will be a little space beneath 
and around the cartridge to permit of a free flow of liquid. 


Nore.—Any type of siphon extractor where the siphon is continuously sur- 
rounded by the vapors of boiling alcohol may be substituted for the above form 
of apparatus. 


SOLUTIONS REQUIRED 
2. 95-per-cent Alcohol.—Specially denatured alcohol, U. 8. Internal Revenue 
Bureau Formula No. 1 or Formula No. 30. 


METHOD 

3. Prepare an extraction cartridge 26 mm. in diameter by 80 mm. in height 
(Schleicher and Schull No. 603 or the equivalent). Place the cartridge in the 
extraction apparatus, Fig. 191, and extract for 30 minutes with boiling 95- 
per-cent alcohol. 

Dry in an air bath at 105° C., transfer to a glass-stoppered weighing bottle, 
cool and weigh. Dry to constant weight. A number of cartridges can be 
prepared and kept in glass-stoppered weighing bottles until wanted. Now 
weigh accurately 5 g. of the lac in a 100-cc. beaker and dissolve in 75 cc. of 
boiling 95-per-cent alcohol by immersing the beaker in a hot water bath until 
all the shellac is dissolved and the wax is in solution. Transfer this solution 
quickly into the weighed extraction cartridge, previously wet with hot alcohol, 
putting the cartridge into a carbon filter tube of suitable size supported in a 
hot water bath (Fig. 192), the outlet tube extending through the bottom of the 
bath allowing the escape of the filtrate. ° Wash all the residue from the beaker 
into the cartridge with hot 95-per-cent alcohol. Put the cartridge in the ex- 
traction apparatus (Fig. 191), and extract for exactly one hour. 


—_— 


¢ 


Foal Fearne 


FIGguRE 191 
Extraction Apparatus for Alcohol-Insoluble Matter in Shellac 


Shellac Analysis 519 


Keep the alcohol boiling briskly during the extraction. The rate of extrac- 
tion may be controlled by the use of an electric hot-point stove, 6 in. in 
diameter, and using the full current of 2.2 amperes at 110 volts. The volume 
of alcohol in the flask should be 125 cc. Protect the flask from drafts. Under 
these conditions the tube should siphon over at least 33 times in 1 hour. The 
condenser should be able to return all the alcohol volatilized during the vigor- 
ous boiling of the contents of the flask, the object being to effect the maxilthum 
extraction during the specified time. : 


The weight of the residue insoluble in alcohol thus obtained divided by the 
weight of the sample, and this quotient multiplied by 100 is the percentage of 
alecohol-insoluble matter in the lac. 


Nore.—When the determination of alcohol-insoluble matter in bleached 
shellac is required, the sample shall be dried if in the form of bars or hanks 
or ground shellac, as the water present dilutes the alcohol to a point where 
solution may not be complete. It is recommended that in preparing shellac 
for this determination, a separate portion be dried by exposure to the air in 
a thin layer, without the application of heat. 


FIGURE 192 


Filtering Device. 
(0) Gooch Filtration Method (Not Applicable for Stick, Seed or Grain 
Lac and Bleached Shellac). 


SOLUTIONS REQUIRED 
4. 95-per-cent Alcohol.—Specially denatured alcohol, U. 8S. Internal Revenue 
Bureau Formula No. 1 or Formula No. 30. 


METHOD 
5. Grind a 50-g. sample fine enough to pass a 40-mesh sieve. Weigh ac- 
curately 2 g. of the sample and transfer to a small beaker, heat the shellac 
with 25 ec. of 95-per-cent alcohol. Prepare a Gooch crucible with an asbestos 


pad in the usual manner* and dry it to constant weight. Arrange the crucible 
tor filtration by suction and pour sufficient boiling alcohol through it to thor- 


oughly heat the crucible. 


Note.—A cold crucible will congeal the wax and prevent filtration. 


*For the preparation of the Gooch crucible see any standard text on 
quantative analysis, for example, Fresenius (Cohn Translation), p. 120, 1904, 
or Treadwell-Hall, third edition, Vol. II, p. 26. 


520 Shellac Analysis 


Immediately filter the boiling solution through the crucible, using suction, 
transfer the insoluble material from the beaker to the crucible, using a “police- 
man” if necessary and a wash bottle containing hot alcohol until the washings 
are colorless and then wash five more times, nearly filling the crucible each 
time with boiling alcohol. 


Norr.—It will be necessary to shut off the suction momentarily to fill the 
crucible. 

Wash off any film of shellac on the sides or bottom of the crucible with hot 
alcohol and dry to constant weight in an oven at 105 to 110°C. The weight 
of the residue in the crucible, multiplied by 100 and divided by the weight of 
the sample, is the percentage of material insoluble in hot alcohol. 


DETERMINATION OF ROSIN 


SOLUTIONS REQUIRED 
6. Acetic Acid.—99-per-cent glacial acetic acid having a melting point of 
14.8° C., free from reducing impurities as shown by its action on a bichromate 
in sulfuric acid. 


NorE.—If these requirements are not met the results of the rosin determina- 
tion will be erratic. 


Iodine Monochloride Solution—Dissolve 13 g. of iodine in a liter of acetic 
acid, using gentle heat if necessary, determining the strength by titration 
with thiosulfate. Set aside 50 to 100 cc. of the solution and introduce dry 
chlorine gas into the remainder until the characteristic color change occurs, 
and the halogen content has been doubled. By titration, ascertain if the halo- 
gen content has been more than doubled, and if so reduce it by adding the 
requisite quantity of the iodine acetic acid solution. A slight excess of iodine 
does no harm but an excess of chlorine must be avoided. 

Chloroform.—Should be chemically pure. 


Sodium Thiosulfate Solution.—Dissolve 24.83 g. of the pure salt in a liter 
of cold, boiled, distilled water. Standardize by titrating against freshly re- 
sublimed iodine. It is recommended that the resublimed iodine be collected 
into a glass-stoppered weighing bottle and weighed after cooling. 


Starch Solution.—Dissolve 0.2 g. of starch per 100 ec. of water and boil. 


METHOD 


7. Introduce 0.2 g. of ground shellac into a 250 ec. dry bottle of clear glass 
with a ground-glass stopper, add 20 cc. of glacial acetic acid and warm the 
mixture gently on top of a hot water bath until solution is complete (except 
for the wax). A pure shellac is rather difficultly soluble; solution is quicker 
according to the proportion of rosin present. Add 10 ec. of chloroform and 
cool the solution to 21.5 to 22.5° C. The bottles should be allowed to stand half 
immersed in a shallow pan of water, well insulated or equipped with a suitable 
thermostat, at least 30 minutes at 21.5 or 22.5° C. before the Wijs solution is 
added. Add 20 ce. of Wijs solution (which shall be at a temperature of 21.5 
to 22.5° C.) from a pipette, having a rather small delivery aperture (about 
30 seconds). Close the bottle, place it back into the pan of water, and note 
the time. The bottles must be kept half immersed in water at 21.5 to 22.5° C. 


aD 


Oe 


Shellac Analysis 521 
sn Snel ere 


during the one hour that the shellac is exposed to the Wijs solution. Agitate 
the bottles occasionally during that hour. 


Norr.—If a number of samples are being run, at least 5 minutes should be 
allowed between the additions of the Wijs solution. 


After exactly one hour, add 10 ee. of freshly prepared 10-per-cent potassium 
iodide water solution, washing into the bottle any Wijs solution on ‘the stopper 
with the same. Titrate the solution immediately with the 0.1 N sodium thio- 
sulfate solution, allowing the solution to run in slowly (about 25 to 30 ce.) 
with vigorous shaking until the solution becomes a straw color. Now add 15 
ec. of freshly prepared starch solution and finish titrating. The end point is 
sharp, as the reaction products of shellac remain dissolved in the chloroform ; 
any color returning after 4 minute or so is disregarded. 


A blank determination shall be run at the same time on the reagents. The 
blank is necessary on account of the well-known effect of temperature changes 
on the yolume, and possibly loss of strength of the Wijs solution. A sample 
of pure shellac of known iodine value should also be run with every set of 
tests on unknown samples. 


In the case of grossly adulterated samples, or in the testing of pure rosin, 
it is necessary to use, instead of 0.2 g. of material, a smaller amount (0.15 g. 
or 0.1 g.) in order that the excess of iodine monochloride may not be too 
greatly reduced, since the excess of halogen is one of the factors in determining 
the amount of absorption. In case less than 25 cc. of the thiosulfate solution 
are required, another test should be made, using a smaller amount of the 
shellac to be tested. 


In weighing shellac, some difficulty is at times experienced on account of 
its electrical properties. In very dry weather it may be found that the neces- 
Sary handling to prepare it for weighing has electrified it, and that it may be 
necessary to leave it on the balance pan at rest for a few minutes before taking 
the final weight. 


No pure shellacs show a higher iodine absorption than 18. As pure shellae 
is relatively a high-priced material and as the variation between its highest 
and lowest figures is not great, it is recommended that 18 should be taken as 
the standard figure for rosin-free Shellac, determined by the method above 
described. 


The determination for added rosin in bone-dry bleached shellae is run 
the same as above, except that the iodine absorption of pure bleached shellac 
is taken as 10 instead of 18. 


It is recommended that the value for the iodine number of rosin be taken 
as 228. The results of using in this method the value of 18 as the iodine 
number of shellac and 228 as the number of rosin, may be that a slightly lower 
percentage of rosin, under some circumstances, will be found than that which 
is actually present. 


The percentage of rosin shall be determined from the formula: 


fedine number of bleached shellac............00eecc.0. ecen det 18 
a se eh OCLE tee Ian rae 2 oe Vege ohn new oe oe ene RN 228 
os “ Si PEAS stat Rg ep ee oe Oe A SORE it 0 cee CRN NUE Ba Oe Lr 

(2-18) 


———__- X 100 = percentage of rosin. 
(228 — 18) " % 


522 Shellac Analysis 
Todine number of bleached shellac....3.....U....una eure 10 
oe of “ . POSIN sce eule vee sie 0 widp ble Wo enals alent onan 228 
= a nD 6 4) ©: 4 F100 > ae IP REE CP v 
(x —10) 
—__-__-.- “~ 100== percentage of toe 
(398-10) : § 


DETERMINATION OF MOISTURE IN SHELLAC 


SAMPLING 

8. Both orange and bleached shellac give off volatile matter at tempera- 
tures approaching 100° C. Bleached shellac alters chemically at these tempera- 
tures, becoming less soluble in alcohol. For these reasons the usual method of 
determining water by heating in the air bath at 100 to 110° C. is not applicable 
in.the analysis of shellac. 

9. Dry Bleached Shellac.—In sampling dry bleached shellac, about 1 1b. 
should be taken from different parts of the barrel and finely ground by run- 
ning through a coffee mill. No attempt shall be made to sieve it. It should 
be rapidly mixed and transferred to a mason jar provided with a screw cap 
and rubber ring seal. The jar should be filled not more than two-thirds full, 
leaving room for a thorough mixing by shaking the contents. It should be 
kept in a cool place and tested as promptly as possible. If too warm, the 
shellac may tend to lump together, in which case the lumps must be broken 
up by shaking the bottle. 

10. Bars or Hanks.—In sampling bars or hanks it is recommended that a 
whole hank be taken. It should be crushed and ground as rapidly as possible. 

11. Ground Bleached Shellac.—Ground bleached shellac may be treated as 
above, bearing in mind that the large amount of moisture present makes rapid 
handling imperative. 

METHOD 

12. Dry-Bleached Shellac_—Weigh 5 g. of the finely ground sample in a 
flat-bottomed dish about 4 in. in diameter and place the dish in a well-venti- 
lated air bath for three to six hours at 38 to 43° C. One or two electric light 
bulbs provide a convenient source of heat. The temperature should not be 
allowed to rise above 48° C. 


NoreE.—With poorly ventilated ovens the drying may take much longer. 
Completeness of drying should be ascertained by continuing the treatment to 
constant weight. Se 


13. Hanks and Ground Bleached.—Proceed as in Section 12, but with the 
exception that the dish and its contents be allowed to dry in the air, or in 
a sulfuric acid desiccator over night before it is placed in the air bath. 

14. Orange Shellac.—Proceed as in the case of Section 12. 


Norr.—Dry-bleached shellac is also termed “bone dry,” “kiln dry,” “vac 
dry,” “bleached shellac.” 


NOTES 
Average commercial orange shellac contains not over 2 per cent of moisture. 
Average commercial regular dry-bleached and dry-refined bleached shellac 
contain not more than 5 per cent of moisture. 
Average commercial regular and refined bleached shellac as ground, hanks 
or bars contain not more than 25 per cent of moisture. 


o —— 


7 wa 


Shellac Analysis bes 


A. 8. T. M. TENTATIVE METHOD OF TEST FOR 
DETERMINATION OF WAX IN SHELLAC 


(“Machine Made” and Dry-Refined Bleached Shellac) 


1. Dissolve 10 g. of shellac with 2.5 g. of carbonate of soda and 150 ce. of 
hot water. Make the solution in a 200-cc. tall form beaker; immerse the 
beaker in a steam or boiling-water bath and stir till the shellac is in solution. 
Then cover with a watch glass, allow to remain in the water bath for 2 or 3 
hours more without agitation, remove beaker from the bath and stand in cold 
water. The wax will form a layer at the top. Filter the solution through 
a 12-cm. folded filter paper, or a Buchner funnel (24 in. in inside diameter) 
may be used. Cover the bottom of the funnel with a disk of filter paper, mix 
1 g. of filter cell with water and pour on the filter. Add 0.5 g. of filter cell 
to the solution, and filter with the aid of a vacuum. After washing out the 
soluble shellac pour on a few cubic centimeters of alcohol to facilitate drying. 
When dry, remove the filter bed and wrap in filter paper, and extract in 
suitable continuous extraction apparatus with chloroform or carbon tetra- 
chloride for 13 to 2 hours. Dry the wax at 105° C. to constant weight. 


Nore.—The filter cell used should be extracted with either of the solvents, 
chloroform or carbon tetrachloride. : 


2. In the case of dry-bleached refined shellac, dissolve 50 g. in 250 cc. of 
alcohol, add 1 g. of oxalic acid and stir till all is dissolved. Then add 0.5 g. of 
filter cell and allow to settle over night. Run the clear liquor through a Gooch 
crucible prepared with asbestos. Wash the sediment of wax and filter cell on 
the crucible with alcohol. Dry at a low temperature, remove the asbestos 
mat, wrap in filter paper and extract in continuous extraction apparatus with 
chloroform or carbon tetrachloride. Dry the wax at 105°C. to constant 
weight. 


Note.—The carbon tetrachloride and chloroform should be redistilled before 
using, as they must not leave a non-volatile residue. 


A. 8. T. M. TENTATIVE METHODS OF 
TESTING SHELLAC VARNISH 


Shellac varnishes are made by dissolving shellac in alcohol and are desig- 
nated in the trade in terms of pounds of shellac per gallon of alcohol, the 4.4.5 
and 5-lb. cut goods being most commonly used. Specially denatured alcohol 
(Formula No. 1) is largely used, and occasionally wood alcohol and butyl 
alcohol are used. Pure grain alcohol, or Formula No. 35 denatured, is used for 
confectioner’s varnish or glaze. 


I. GENERAL 


1. (a) All tests, unless otherwise stated, shall be made at room temperature 
between 21 and 32° C. (70 and 90° F.)). 

(b) The sample of shellac varnish shall be thoroughly agitated in the con- - 
tainer immediately before portions are removed for the various tests and the 
unused portion shall be kept in a tightly stoppered glass container, in a dark 
place. 


524 Shellac Analysis 


II. DETERMINATION OF COLOR 
2. The color of the well-shaken sample shall be compared with the color of 
the well-shaken sample of shellac varnish mutually agreed upon for color by 
the buyer and seller. The color comparison shall be made in clear glass tubes 
of the same diameter. 


Ill. DETERMINATION OF NON-VOLATILE MATTER 
Method (a). 


APPARATUS 

3. The apparatus shall consist of the following: 

(a) A weighing bottle for volatile liquids or a Grethan pipette. 

(b) A tin-foil dish, approximately 1} in. in height and 23 in. in diameter. 

(c) Prepared Sand, prepared as follows: Sieve sea-sand to remove any 
foreign material. Digest with hot HCl for about one hour. Wash with water 
to remove all the acid and soluble impurities. Ignite and put in a desiccator to 
cool. Preserve in a tightly stoppered bottle. 


PROCEDURE 

4. Put 10 g. of the prepared sand and a short glass rod in the tin-foil dish. 
Record the exact weight of the dish and contents. Transfer about 1 g. of 
the sample from the weighing bottle to the dish. Record the exact weight of 
the sample taken which will be the difference in weight of the weighing bottle 
before and after the removal of the sample. Thoroughly mix the varnish and 
sand with the glass rod and place the dish in an oven maintained at 105° C. for 
one hour. Remove the dish from the oven, allow it to cool and weigh. The 
increase in weight of the tin-foil dish containing the sand and glass rod is the 
weight of the non-volatile matter in the sample of varnish taken. 

Method (b). 

5. Follow the procedure given in the Standard Methods of Testing Oleo- 
Resinous Varnishes (Serial Designation: D 154) of the American Society 
for Testing Materials,* for non-volatile matter in oleo-resinous varnish, with 
the exception that the weight of sample taken shall not exceed 1.5 g. With 
varnishes made by “cutting” over 5 lbs. of shellac per gallon of alcohol, add 10 
g. of sea sand, prepared as described in Section 3 (c), to the container and 
mix with the sample by means of a short glass rod (previously weighed with 
the container and sand). 

6. (a) Since bone dry white shellac may lose up to 5 per cent of its weight 
when heated at 105° C., the weight of non-volatile matter found in the case of 
white shellac varnish should be divided by the factor 0.95. 

(b) On account of the efforts of the orange varnish manufacturers to 
produce cleaner varnish for the trade by the use of centrifuge machines and 
improved filtration apparatus, the same allowance of 5 per cent, which is made 
in calculating white shellac varnish body, shall be used in determining clari- 
fied orange varnish body. This 5-per-cent allowance is based on the fact that 
2 per cent of moisture has always been allowed in the calculation, and in 
addition the 3 per cent of insoluble matter customarily encountered in varnish 
grades of orange shellac is eliminated by the modern methods of varnish 
production. 


*1924 Book of A.S.T.M. Standards. 


Te ee 


Shellac Analysis 525 


The calculations of the body of white and orange shellac varnishes are 
made according to the methods shown in the following examples: 


Example. 
White Shellac Varnish and Clarified Orange Shellac Varnish: 
Suerte Ore varnish CAken. 6.50.06. ee eee ee wees 1.2973 g. 
iveimno or residue (after drying)............3..6 Oieao f. 


0.5235 
0.95 X 1.2973 
This percentage corresponds to 5 lb. per gallon. 


The above orange-varnish calculation refers to ready-cut varnish as 
obtained in the regular paint and varnish shops. 


Per cent of body = X 100 = 42.45 per cent. 


The better grades of orange shellac, which contain little insoluble matter, 
can and are cut in alcohol and simply strained through an S0Q-mesh screen. 
Such a varnish would contain practically all the finely divided inert matter 
and the calculation of the body of such a varnish would be made as follows: 

Since dry orange shellac may lose up to 2 per cent of its weight when 
heated at 105° C., the weight of non-volatile matter found in the case of orange 
shellac varnish should be divided by the factor 0.98. 

The calculation of the body is made according to the method shown in the 
following example: 


Example. 
Unclarified Orange Shellac Varnish: 
Berar eGr VATHISH TAKEO ck. oa ce cnc oe ececceee 1.3200 g. 
MW ermut 0: residue (after. drying)........0.5...e00. 0.5491 g. 


0.5491 
0.98 X 1.3200 


This percentage corresponds to 5 lb. per gallon. 


Per cent of body = xX 100 = 42.45 per cent. 


(ec) To convert the percentage of solids (residue) of the varnish into 
pounds per gallon, from the percentage of solids expressed in pounds of solids 
in 100 lb. of varnish, the pounds of solvent is found by difference. The weight 
of solvent divided by 6.7793 (the weight of one gallon of denatured alcohol 
(Formula No. 1) at 15.5° C. (60° F.), gives the number of gallons of alcohol 
present. From this the number of pounds of shellac per gallon of alcohol is 
determined. 


Example. 
100 — 30.68 (solids found) = 69.32 lb. of alcohol. 
69.32 
6.7793 
30.68 
10.23 


For convenience, tables are appended hereto giving pounds of shellac per 
gallon for varnishes for various specific gravities. See page — 
IV. DETERMINATION OF MATTER INSOLUBLE IN HOT ALCOHOL 
7. (@) Matter insoluble in hot alcohol shall be determined by the continuous ~ 
extraction method or by the Gooch filtration method as given in the Standard 
Methods of Testing Shellac (Serial Designation: D 29) of the American 
Society for Testing Materials.* 


= 10.23 gallons of alcohol. 


= 3 lb. per gallon. 


*1924 Book of A.S.T.M. Standards. 


526 Shellac Analysis 


(b) In the ease of the continuous-extraction method, weigh an amount of 
shellac varnish corresponding, as closely as practicable, to 5 g. of non-volatile 
matter, while with the Gooch filtration method take a weight of sample cor- 
responding closely to 2 g. of non-volatile matter. 


V. DETERMINATION OF WAX 
8. In the determination of wax, dilute an amount of the varnish that will 
contain approximately 10 g. of dry shellac with 95-per-cent specially-denatured 
aleohol to about 200 ce. and proceed as in the Standard Method of Test for 
Determination of Wax in Shellac (Serial Designation: D 29) of the American 
Society for Testing Materials* 


VI. DETERMINATION OF PURITY 
A. Qualitative Tests 
9, (a) Copal.—Filter some of the varnish through dry paper into a large 
test tube 6 by 3 in.). To 10 ce. of the filtrate add 99-per-cent methyl alcohol 
to nearly fill the tube and thoroughly mix. The formation of a precipitate 
after standing is an indication of copal. Shellac free from copal should remain 
clear under the conditions given above, , : 
(b) Rosin.—Add 20 ec. of absolute alcohol or glacial acetic acid (melting 
point 13 to 14°C.) to 5 ee. of the varnish and thoroughly mix. Add 100 cc. 
of petroleum ether and again thoroughly mix. Add approximately 2 liters of 
water and separate a portion of the ether layer (at least 50 ec.) and filter if 
cloudy. Evaporate the petroleum ether and test the residue by the Halphen- 
Hicks reagent as follows: 


Solution A.—One part by volume of phenol dissolved in 2 parts of carbon 
tetrachloride. 

Solution B.—One part by volume of bromine dissolved in 4 parts of carbon 
tetrachloride. 


Add 1 to 2 cc. of solution A to the residue left after evaporation of the petrole- 
um ether solution. Pour this solution into a cavity of an ordinary porcelain 
color reaction plate and fill an adjacent cavity with solution B. Cover the 
plate with a watch glass and note the color, if any, produced by the action of 
bromine vapors on solution A. A decided purple or blue color is an indication 
of rosin. 

B. Determination of Iodine Number 

Method (a). 

10. (a) With the percentage of solids known, weigh accurately in a suit- 
able pipette, or weighing bottle for volatile liquids, an amount of varnish cor- 
responding to 0.20 g. of dry shellac and transfer to a 250-cce. glass-stoppered © 
bottle. In case heavy adulteration is suspected, weigh an amount of varnish 
corresponding to 0.15 g. of shellac or less if necessary. 

(b) Warm the bottle in a water bath at a temperature of 75 to 80° C, for 
about 15 minutes, aspirating the alcohol vapor until the residue is practically 
dry. Cool and add 20 ce. of acetic acid (melting point, 14.8° C.). Proceed in 
accordance with fhe method for iodine number described in the determination 
of rosin in the Standard Methods of Testing Shellac (Serial Designation: D 
29) of the American Society for Testing Materials.* 


*A.S.T.M. Standards Adopted in 1925. 


Shellac Analysis 527 
eee 


ALTERNATE PROCEDURE 
Method (Db). 

11. Transfer about 1.5 cc. of the varnish by means of a pipette to a flat- 
bottomed glass or porcelain dish at least 8 em. in diameter. Add 1 fo 2 COLOL 
95-per-cent alcohol to spread the varnish evenly over the bottom of the dish. 
Heat the dish and contents at 75 to 80° C. for one-half hour. Scrape the resi- 
due from the dish, accurately weigh 0. 20 g.., and transfer to a 250-ce. glass- 
stoppered bottle. In case of badly adulterated samples, a proportionately 
smaller weight of sample should be taken. Proceed in accordance with the 
method for iodine number described in the determination of rosin in the 
Standard Methods of Testing Shellac (Serial Designation: D 29) of the 
American Society for Testing Material.* 


12. (a) If a qualitative test shows the presence of copal but no rosin, the 
amount may be estimated from iodine number, taking the iodine number of 
copal as 180 and making the calculation in an analogous manner to that for 
rosin described in Section 7 of the Standard Methods D 29. 


(b) If a qualitative test shows the presence of rosin but no copal, the 
calculation of the percentage of rosin may be made as described in Section 
7 of the Standard Methods D 29. 


APPENDIX 


Information concerning the volatile portion of a shellac varnish May be 
obtained by distilling approximately 50 ce. of varnish to dryness (avoiding 
decomposition of the shellac through excessive heat at the end) and determin- 
ing the boiling range of this distillate by a redistillation. A portion of the 
final distillate may be diluted with water to ascertain if other solvents, such 
as naphtha or benzol, have been added. These will] separate on dilution and 
the layer formed may be measured. 


RELATION OF POUNDS Or SHELLAC PER GALLON TO SPECIFIC GRAVITY 


— —S— 


Wire SHELLAC VARNISH: Dry BLEACHED SHELLAC (5 PER CENT MOISTURE), 
DENATURED ALCOHOL, FoRMULA No, 1, 95-PER-CENT, 


SHELLAC, SPECIFIC WEIGHT 


LB. PER GAL. GRAVITY DEG. PER 1 GAL. 
OF ALCOHOL 15.5° C. (60° F.) Baumnp VARNISH, LB, . 
Taking Weight of Water 1 gal.—8.33 Ib. 
ne 0.9056 24.60 7.544 
A 0.9167 22.70 7.636 
_ Er 0.9278 20.90 7.729 
SS ee 0.9375 19.33 7.809 
a 0.9464 "17.92 7.884 
a 0.9530 16.90 7.938 
sek s< 2 Ae 0.9597 15.90 7.994 


*1924 Book of A.S.T.M. Standards. 


528 Shellac Analysis 


ORANGE SHELLAC VARNISH: TN SHELLAC 2 PER CENT MoIstuRE), DENATURED 
ALCOHOL, FoRMULA No. 1, 95-PER-CENT, 
Taking Weight of Water 1 gal.—8.83 Ib. 


Re Gatebase rigs aiaer ey 0.900 25.55 7.497 
1 eee reer n Se otk 0.9114 23.6 7.592 
es A a eee See 0.9228 oy 7.687 
OY, Gal apres Wes Mar ent 0.9318 20.25 7.762 ; 
Bee of Seo 5 ee oe 0.9895 19.0 - 3 7.926 | 
Bo kate eee ee 0.9500 17.36 7.914 
Bilas cs ety eee 0.9554 16.53 7.958 


Note 1.—Shellac varnishes will not always agree exactly with the specific 
gravity given above, estimated at 15.5° C. (60° F.). They will vary somewhat, 
due to more or less moisture and insoluble matter contained in the white and 
orange shellacs and also to loss of solvent by evaporation. However, the 
figures given agree closely with theoretical and practical results. 

Nore 2.—If 10 lb. of shellac is cut in 1 gal. of alcohol the yield is 2 gal. of 
varnish, hence 10 lb. of shellac cut in alcohol is equivalent to 1 gal. 


Example. ; 
4 lb. shellac cut in 1 gal. alcohol yields 1.4 gal. varnish 
44 lb. shellac cut in 1 gal. alcohol yields 1.45 gal. varnish 
5 Ib. shellac cut in 1 gal. alcohol yields 1.50 gal. varnish 


The following table shows corresponding percentages of gum and alcohol in 
shellac varnishes of the following pounds of gum cut per gallon, No. 1 Specially 
Denatured Alcohol 95-per-cent, by volume at 15.5° C. (60° F.). 


POUNDS OF 
GUM PER 
GALLON OF ; GUM, ALCOHOL, 
ALCOHOL PER CENT PER CENT 
BO eis oc dele \ave'e sla eie)o 5 Oa tace tye ae ee ee oe 30.68 69.32 
BiDe. oo vlaie «ale ib dpi acnce Bie: Ghee ale eters ce vies betel iat eee 32.41 67.59 
BO ss hada bn aw tte c ele Otic eaeee Se eens oe ee 34.05 65.95 
ay 65 EY Aen She N ere ee A oe 35.61 64.39 
AAV, os Saw sy ©. scale & © Gael suave RI ReLn inion el Ps alta ae 37.11 62.89 
A ow ievece im anaemia Utah "ecole Malle Scheie Up se ek 38.54 61.45 
he FOE aed -d win. wha wiwea. o mile eine Costin te nie eens ete 39.90 60.10 4 
ATE b vcalGn 2 dc a Rew ee bcis ake SiGe io ea ea 41.20 58.80 ; 
5.0 oc Sie Oe Ss bbe ee Mes She pe eal ae 42.45 57.55 
Ty 45 a ere a ND eI aK ER 43.65 56.35 
BBs sucks ale bw Gio oF miele 6a oum gonie othe Gate tame raceatn ean 44.79 55.21 
Wy {i Pee ee a ere ee Pe ee ee ee ae 45.89 54.11 
GOs oo Sv 9 bis 6 we el bac ete aoe e 46.98 53.02 


The weight of 1 gal. of alcohol (No. 1 Special) at 15.5° C. (60° F.) is 6.7793 
lb. according to Regulations No. 61, U. S. Internal Revenue. 

The table given above is taken from the Official Booklet of the United 
States Shellac Importers’ Association. 


Note 3.—Method (a) covering Determination of Non-Volatile Matter in 
Varnish is the official method of the United States Shellac Importers’ 
Association. 

Nore +.—The above figures are the most important in the tables to the 
varnish industry as considerable shellac varnish is now sold by weight, or the 
gallonage is determined by dividing the net weight by its corresponding factor. 

Nore 5.—Hydrometers should not be employed to determine the specific 


ese ee 


gravity or degree Baumé of a shellac varnish, as readings so obtained are 
unreliable and inaccurate. The specific gravity of a shellac varnish can be ¥ 
accurately determined either with a specific gravity bottle (pyknometer) or j 


by weighing accurately 100 cc. of the varnish at 60° F. in a 100-ce. graduated 
flask, which has been calibrated with distilled water at the same temperature. 


Shellac Analysis 529 


Direct Method for Rosin in Shellac.—A direct method for 
determining the amount of rosin in shellac has long been de- 
sired. Such a method is being worked out by the Bureau of 
Standards and promises to be very satisfactory. It is based 
upon the solubility of rosin in certain hght fractions of petro- 
leum hydrocarbons. See the Bureau of Standards Techno- 
logic Paper No. 232. This petroleum ether method has not 
superseded the Wijs iodine method where a numerical value 
for percentage of rosin is desired. It is, however, of great 
value in determining the adulteration of shellac varnishes. 


Steele Modification of the McIlhiney Method for the Detec- 
tion and Estimation of Adulterants in Shellac Varnish.—Pe- 
troleum ether distilling between 55 and 75° C.* was obtained 
by the distillation on the steam bath of either commercial pe- 
troleum ether or aviation gasoline, fighting grade.+ Glacial 
acetic acid was diluted with water until its solidification point 
was between 13 and 14° C. 


Method.—In case of a shellac varnish, determine the per- 
centage of nonvolatile matter. Place a portion of the well 
mixed sample in a stoppered container. Weigh the container 
and sample. Transfer a weight of the sample corresponding 
as closely as practicable to 2 g. of nonvolatile matter to a 2- 
hter Florence flask, the neck of which has a volume of over 
100 ce. and restopper the container. Weigh the container 
again and by difference calculate the exact weight of the por- 
tion transferred to the flask. Calculate the exact weight of 
shellac in the sample taken from the percentage of nonvolatile 
matter in the varnish. The procedure from this point is the 
same for dry and cut shellac. Add 20 ce. of the special acetic 
acid and heat the flask until the shellac resin and wax are dis- 
solved. With certain shellac adulterants there may be a small 
amount of resin which cannot be dissolved. Cool the flask to 
room temperature (19-21° C.) hereupon a part of the natural 
shellac wax usually separates. Add slowly from ‘a pipette 50 
ec. of the petroleum ether cooled to 19-21° C., with constant 
shaking of the flask, allowing one to two minutes for the addi- 
tion. Add all at once from a graduated flask 100 ec. more of 
the petroleum ether kept at 19-21° C., stopper the flask and 


* A fraction with initial boiling point of 40° C. should be satisfactory, 
provided it is not used in extremely hot weather . 
+ Bureau of Mines Technical Paper No. 323, p. 1. 


530 Shellac Analysis 

a 
shake vigorously. While shaking the flask, slowly add tap 
water kept at 19-21° C., until the shellac has separated as an 
amorphous mass. Half fill the flask with water and agitate 
so as to thoroughly wash the ether layer. Add water until 
the petroleum ether layer nearly fills the neck of the flask, cork - 
and let the flask stand until the ether layer is free from sus- 
pended particles. Transfer 100 ce. of the ether layer to a 100 
ec. graduated flask. It is convenient to fit the large flask with 
a two-hole stopper with tubes arranged like a wash bottle, so 
that the ether solution can be blown into the graduated flask. 


Evaporate the 100 cc. of petroleum ether solution, portion 
wise if necessary, in a small weighed Erlenmeyer flask on a hot 
plate. When the dry point is reached, suck out the residual 
solvent vapors, cool the flask, and weigh. The weight of the 
residue multiplied by 150 and divided by the weight of shellae 
taken is the percentage of ‘‘matter soluble in petroleum 
ether.’’ Dissolve this residue in 25 ee. of a mixture of equal 
volumes of 95 per cent denatured alcohol and benzol (the mix- 
ture should be previously titrated to a faint pink color with 
dilute alkali, using phenolphthalein as an indicator) and ti- 
trate in the cold with 0.1 N alcoholic sodium hydroxide with 
phenolphthalein as an indicator. Calculate the acid number 
of the ‘‘matter soluble in petroleum ether’’ (milligrams of 
KOH required for 1 g. of petroleum ether residue). Transfer 


Suggested Method for Rating Samples of Shellac 


Petroleum Acid number of 
ether soluble Ros:n test residue Purity 
percentage 5 
7.0 OF esas, a2} INCZATIVON Se) ernie 60-90 Ris a. eens Pure. 
7,058.0. F008 2 Positivec. aan Se ae May be greater or | Slightly adulterated; probably 1-2 per cent 
less than 90. rosin, as in ‘‘Superfine”’ 
70-8032 nen Werativ Gh, sc eratacee ae 0 oy Aine ee. sors Suspicious; no adulteration proved. 
8.0-12.0...... POsitivednncok tenes Generally, but not | Somewhat adulterated; probably a “T.N.” 
always over 90. shellac. 
80292. 05 au Negative: ci normconlonncs Oe hats nate Somewhat adulterated with an adulterant 
other than rosin. 
12.0-20.0.....) Positive or nega- }|..... GO. = ccm Badly adulterated; possibly as high as 40 
tive. per cent adulteration. 
ver QO. Oke cals ores AO pirate ascent iiaecs re bo Weegee Paes Ac Grossly adulterated; possibly no shellac 
present. 


most of the petroleum ether layer remaining in the Florence 
flask to a small beaker or flask and evaporate to dryness. | 
Test this residue for rosin by means of the Halphen-Hicks test 
already referred to. Report a faint purple or blue coloration 


Shellac Analysis 531 


as ‘‘faint test for rosin’’ and a deep purple or blue as ‘‘de- 
eided test for rosin.”’ 


An examination of the results on many samples tested by 
this method indicate that a large number of the samples of 
shellac were free from rosin, as shown by a qualitative test 
and by an iodine value below the arbitrary accepted limit of 
18. Such samples can probably be safely considered as un-— 
adulterated shellacs. These samples of pure shellac, with 
few exceptions, yielded values between the limits of 6.0 and 
7.0 per cent for material soluble in petroleum ether and acid 
values for this residue between the limits of 60 and 90. 


Testing the Effect of Metals and Solvents upon the Darken- 
ing of Shellac Solutions.—Producers of shellac varnishes have 
occasionally noted darkening of their products which have 
stood for a considerable period of time upon dealers’ shelves 
or in store rooms. It was thought that the type of alcohol 
used in cutting the shellac may have had some influence upon 
this phenomenon, or that metals taken into solution during 
the cutting process may have been responsible. While as a 
rule wooden barrels are used for agitating shellac, metal bar- 
rels have sometimes been employed, or the fittings in the cut- 
ting apparatus may have contained iron parts. Iron spigots 
may have been employed, or the shellac solution may 
have come in contact with other metals previous to filling 
into small containers. Containers used for shellac may be 
ordinary tin cans or, as in many instances as at present, glass 
bottles fitted with metal covers which are insulated from con- 
tact with shellac by paper gaskets. 


In order to get some information as to the cause of this 
darkening phenomenon, a series of tests have just been made 
upon four grades of shellac. These consisted of Clean Dry 
Bleached Shellac, Superfine Shellac, Fine Orange Shellac, and 
TN Shellac, the latter being one of the lower qualities import- 
ed into this country. All grades of shellac contain organic 
acids, and therefore may be susceptible to reaction in contact 
with various metals. The five grades of alcohol experimented 
with were as follows: | 


COMPLETELY DENATURED ALCOHOL FORMULA No, 1 


100 parts by volume of Ethyl Alcohol] (not less than 160 proof) 
10. ~=—s parts by volume of Approved Wood Alcohol 
0.5 part by volume of Approved Benzine (Kerosene) 


532 Shellac Analysis 


SPECIALLY DENATURED ALCOHOL FORMULA No. 2 


100 parts by volume Ethyl Alcohol (not less than 160 proof) 
+) parts by volume Approved Wood Alcohol 


SPECIALLY DENATURED ALCOHOL FORMULA No. 2-B 


100 parts by volume Ethyl] Alcohol (not less than 160 proof) 
0.5 part by volume Specified Benzol 
(The above formula is allowed in a closed and continuous process only.) 


SPECIALLY DENATURED ALCOHOL FORMULA No, 3-A 


100 parts by volume Ethyl Alcohol (not less than 160 proof). 
u parts by volume Commercially Pure Methyl Alcohol having a specific 
gravity of not more than 0.810 at 60° F 


= { 
COMPLETELY DENATURED ALCOHOL FORMULA No. 5 


100 parts by volume Ethyl Alcohol (not less than 160 proof) 
2 parts by volume Approved Wood Alcohol 
0.25 part by volume Approved Pyridin Bases 
0.50 part by volume Approved Benzine (Kerosene) 


General information regarding the specifications used in 
purchasing the various denaturants referred to in the above 
formulas is contained in Appendix to Regulations No. 61, a 
pamphlet issued by the Treasury Department, entitled ** For- 
mulae for Completely and Specially Denatured Alcohols.”’ 
This may be obtained from the Government Printing Office, 
Washington, D. C., for five cents per copy. 


The various anata referred to above were cut in the alco- 
hols in the proportion of 3 lbs. of shellac per gal. of alcohol. 
The cutting was done in glass. This produced twenty differ- 
ent samples. Each of these was divided into four parts and 
placed in four glass jars with paper-insulated caps. In one of 
these jars for each group there was placed a few bright iron 
carpet tacks. In another jar a few small strips of sheet tin 
were placed. In the third jar a few small pieces of mossy 
granulated zine were placed. The remaining jar of shellac 
was used as a blank, no metal being added to it. These four 
sets of tests (a total of eighty jars) were then shaken every 
day for a period of 5 minutes until a test period of six weeks 
had elapsed. During this time frequent inspections were 
made. It was noted that the shellacs containing the iron, tin, 
or zine gradually darkened in color, while those that did not 
contain metal were only slightly affected by light. It was 
also noted that the clear liquid in each sample, above the set- 
tled wax, wherever metals were placed in the solutions, was 
very much darker than those without metals. This was espe- 
cially true of the orange shellac. 


Shellac Analysis 533 


It was also noted that the grade of alcohol used seemed to 
affect the color to some extent. The samples remaining the 
lightest in color were almost invariably those produced with 
Specially Denatured Formula No. 1 or Completely Denatured 
Formula No. 1. Specially Denatured. Formula No. 3-A was 
next in order. This was followed by Specially Denatured 
Formula No. 2-B. The darkest of all in practically every in- 
stance were those made with Completely Denatured Formula 
No. 5 which contained pyridin. It is probable that the pyri- 
dine base may have exerted some action upon the shellac, 
which would cause the darkening phenomenon. This, how- 
ever, was not nearly as pronounced as the effect of the metals. 

A comparison of the colors of the shellacs at the conclusion 
of the tests showed that the sheets of (tin-coated iron) tin 
caused the color to change to a very deep greenish brown. 
Next in order came the iron which had a somewhat similar 
effect but not as pronounced as the tin. The zine caused a 
change to a rather pleasing shade of brownish red, slightly 
darker than the original sample but not as dark as the colors 
produced by the tin and the iron. In this connection, it is 
interesting to note that the type of tin plate usually produced 
today probably contains very much less tin than several 
years ago. ‘This is due to the present shortage of tin. Thus, 
for instance, tin cans may contain a coating of tin which does 
not thoroughly coat the iron. Pin holes are present and the 
exposed base metal is therefore subject to fairly rapid cor- 
rosion when in contact with corrosive liquids. It is therefore 
possible that the results shown in these tests with the sheets 
of tin plate were due more to the effect of the iron than to the 
tin, the sheared specimens leaving reactive surfaces of un- 
coated iron. 

Another interesting phenomenon noted was the viscosity 
of the various samples after standing. For instance, in every 
case the shellacs treated with metals were considerably higher 
in viscosity than the original samples in which metal was not 
placed. Asarule, the difference in viscosity ranged from one- 
half to one bubble on the Gardner-Holdt viscometer. The 
shellacs were rated for viscosity in the following order: 


Original Shellac : Iron contaminated shellac 
Zine contaminated shellac Tin contaminated shellac 


534 Shellac Analysis 


The latter was very much greater in viscosity than the 
others. 


As a result of these tests, it would appear that Specially 
Denatured Formula No. 1 and Completely Denatured For- 
mula No. 1 are more suitable for cutting shellac than the other 
three. It would also appear that shellac should be cut in ap- 
paratus containing very little if any metal. It would further 
appear that shellac should be stored preferably in glass con- 
tainers. ‘Terne plate containers have also proved quite satis- 
factory and are doubtless superior to tin plate containers. 


CHAPTER XXX 


BITUMINOUS PAINTS, VARNISHES, CEMENTS AND AUTOMOBILE 
BLACK BAKING ENAMELS 


During the past five years the use of bituminous substances 
for cold application as protective coatings has increased con- 
siderably. This has resulted in an urgent demand for speci- 
fications and methods for analyzing and testing them. Here- 
tofore, reliable methods have not been available. The follow- 
ing descriptions and methods, many of which were prepared 
for this volume by E. H. jevsguen formerly of the Bureau of 
Standards, are to be highly recommended. 

Bituminous compositions for cold application can be di- 
vided into paints, coatings, varnishes, japans, and plastic 
cements. 


Bituminous Paints.—Bituminous paints are generally mix- 
tures of a bituminous material and a volatile solvent which 
are of brushing consistency and which dry and harden by the 
evaporation of the volatile solvent. They may contain min- 
eral filler and pigment and small amounts of fatty matter. The 
term, paint, as defined by the A. 8. T. M. is, however, misap- 
plied to these materials except in the few instances where pig- 
ment is added. 

Bituminous paints are marketed under various names but 
the most important kinds can be classed as dampproofing and 
roofing paints. Dampproofing paints are used almost exelu- 
sively on masonry and concrete to prevent the absorption or 
penetration of moisture and are rarely exposed to the weather, 
being protected in some manner. The two most common 
kinds are stone backing and plaster bond. 

Stone backing is a solution of a bituminous material in a 
volatile solvent used for coating all surfaces except the ex- 
posed face of cut stone, concrete blocks, ete., to prevent stain- 
ing, efflorescence, or other discoloration of the exposed face. 
It is of heavy brushing consistency, invariably dries to a tough 
flexible film free from tackiness and which will not chip or 
flake off in handling. They are composed either of asphaltic 
or coal tar materials. 

Plaster bond is a solution of a rather soft bituminous sub- 
stance in a suitable volatile solvent for coating the inside of 


536 Bituminous Paints 

lene ne ne ene CEASE INE 
exterior walls of brick, tile, stone, etc., before plastering to 
prevent staining, etc. Its value as a means of increasing the 
bond between the plaster and the wall is a matter of question. 
Plaster bonds are usually made from asphaltic materials and 
may contain fatty materials, rosin, rosin oil, aluminum stear- 
ate or oleate or other heavy metal soaps. They are of heavier 
consistency than stone backings and dry to soft, flexible films 
which have a tendency to remain permanently tacky or sticky. 

Roofing paints are used for painting metal roofs and for 
recoating prepared and built-up bituminous roofing. They 
vary in consistency from those which can be applied with an 
ordinary paint brush to those which require a stiff bristle 
dauber or three knot roof brush for application. The former 
are usually called roofing paints and the latter roof coatings. 
Roofing paints consist of a bituminous material thinned with 
a solvent and may contain fine mineral filler or pigments. 
When pigments are present, some drying or fatty oil may be 
used. Roof coatings are of heavier consistency than roof 
paints and contain mineral or other filler usually of a fibrous 
character in the proportion of about 5 to 15 parts per 100 parts 
of finished paint. Their common trade name is liquid fibrous 
asbestos roof coating. Roof paints and coatings may be made 
from either asphaltic or coal tar materials. When using them 
for prepared or built-up roofing only asphaltic materials should 
be applied over asphaltic roofings and only coal tar materials 
over roofings made with coal tar materials. 

Occasionally paints are encountered which consist of a bitu- 
minous substance dissolved in carbon bisulphide or carbon 
tetrachloride. These paints are based on the formula given 
in the patent of Pearce & Beardsley. Their chief advantage 
is that they dry rapidly and give relatively thicker dried films 
than paints of the same consistency made with ordinary sol- 
vents. 


Bituminous Varnishes.—Bituminous varnishes are mixtures 
of a bituminous material and fatty oil thinned to a suitable ~ 
consistency with a volatile solvent which dry partially by the 
evaporation of the volatile solvent and partially by the oxida- 
tion of the fatty oil. The toughness and general characteris- 
tics of the film obtained from bituminous varnishes are in- 
fluenced by the fatty oil present. Bituminous varnishes may 
be either long or short oil but those most commonly sold are 


Bituminous Paints 537 
_]—$—$—$— 
the short oil type with about one part of oil to four, of bitu- 
minous material. Hard bituminous materials are generally 
used and include gilsonite, hard native and residual oil as- 
phalts, glance pitch, manjak, wurtzelite pitch, grahamite, and 
fatty acid pitches. 3 

Bituminous Japans.—Bituminous japans are mixtures of 
bituminous materials with or without fatty oil and resins and 
volatile solvent the drying and hardening of which is brought 
about by baking. The cheaper grades of japan usually con- 
sist of a bituminous substance dissolved in a solvent, the bet- 
ter grades are mixtures of a bituminous substance with fatty 
acid pitch, drying oils, and resins, with or without small 
amounts of pigment. Most black insulating varnishes and 
Brunswick Black are of this character. : 


Bituminous Plastic Cements.—Bituminous plastic cements 
are mixtures of trowelling consistency of bituminous materi- 
als with or without fatty oil and volatile solvent and contain- 
ing about 15 to 40 parts of filler, generally of a fibrous charac- 
ter, per 100 parts of cement. They are applied in thick layers 
and usually dry to tough coatings which remain plastic for 
long periods. They are made either from asphaltic or coal 
tar materials and the same precautions should be taken in 
their use on bituminous roofing as with roof paints and coat- 
ings. Pine tar, pine tar oil, and hard wood tar are sometimes 
used to improve spreading quality and to modify the odor of 
coal tar materials. 


Constituents oF Biruminovs Paints, VARNISHES, 


Cements, Etc. 


The following materials are generally used in these prod- 
ucts, although any material entering into the manufacture 
of oil, paints, varnishes, etc., is likely to be used. 


(1) Bituminous Materials. 


Petroleum Asphalts Glance Pitch 

Trinidad Asphalt Wurtzelite Pitch 

Bermudez Asphalt Coal Var Pitch? © 

Gilsonite. Water Gas Tar Pitch 
Grahamite Pine Tar and Wood Pitches 


Manjak Fatty Acid Pitches 


538 Bituminous Paints 


a 


(2) Fatty and Resinous Materials. 


Linseed Oil Castor Oil 
China Wood Oil Rosin 
Cottonseed Oil Fossil Resins 
Rosin Oil 

(3) Driers. 


Any drier used in oil paints and varnishes. 


(4) Thonners. 
Petroleum Distillates Pine Oil and Pine Tar Oil 


Coal Tar Distillates Carbon Bisulphide 

Turpentine Carbon Tetrachloride 
(5) Fillers and Pigments. é 

Asbestos Slate Dust 

Asbestine Silica 

Clay Rag Fibers 

Portland Cement Jute Fibers 

Limestone Dust Paper Pulp 

Gypsum 


Meruops or ANALYSIS AND TEST 
(A) Volatile and Nonvolatile: 


(1) Materials without filler—Heat a 1.5 to 2 gram sample 
in a tared metal dish at 105° to 110° C. for three hours. The 
loss in weight is calculated as volatile. 


(2) Materials with filler—Heat a 3 to 5 gram sample 
spread out to a thin layer in a tared metal dish at 105° to 
110° C. for seven hours. The loss in weight is calculated as 
volatile. 


(B) Separation and Examination of Thinner: 


(1) Low boiling thinners.—Distill 100 grams of the sample 
with steam at a temperature of 130° C., collecting the distillate - 
in a separatory funnel. Stop the distillation when 300 ce. of 
water has distilled. When the distillate has separated into 
two distinct layers, draw off the water, and examine the dis- 
tillate for refractive index, specific gravity, soluble in 38 N. 
sulphuric acid, dimethyl sulphate, or by any other tests neces- 
sary for its identification. If no pigment or filler is present 
the residue in the flask may be dried and used for further 
testing as in paragraph (D). 


Bituminous arnt 539 


(2) High boiling thinners.—Distill 100 grams of ‘the sam- 
ple in a 200 ce. Engler distilling flask at the rate of about one 
drop per second, avoiding overheating, which may crack the 
bituminous material. Collect fractions up to 170° C., and 170° 
to 300° C., at which point the distillation is stopped. In most 
eases the thinner will all have distilled at a point below 300° C. 
and the distillation should be stopped when this occurs. The 
distillates are examined asin (1). The residue in the flask is 
allowed to cool until vapors are no longer evolved, when it is 
poured out into a suitable container and, if no pigments are 
present, preserved for further testing as in paragraph (D). 


(C) Fillers, pigments and free Carbon: 

Separate the fillers, pigments, and free carbon from the ve- 
hicle by any of the following methods: 

(1) Weigh accurately about 10 grams of the sample into a 
centrifuge tube. Add about 25 cc. of benzol and stir so as to 
break up the sample, then add about 25 cc. more solvent and 
centrifuge until well settled. Decant the supernatant liquid 
and repeat the extraction twice with 50 ce. portions of benzol 
and then with a mixture of equal parts of benzol and carbon 
tetrachloride until the supernatant liquid is colorless. Dry 
residue in tube at 105° to 110° C. for one hour and weigh. Pre- 
serve extracts for further examination of vehicle. The in- 
soluble residue contains the pigment and fillers, and mineral 
matter occurring naturally in the bituminous materials (7. e., 
Trinidad and Bermudez asphalts) and free carbon from coal 
tar pitches. 


(2) Weigh accurately about 5 grams of the sample into a 
small beaker, add 25 cc. of carbon bisulphide or carbon tetra- 
chloride or benzol (if an examination of the vehicle is to be 
made), break up the sample by stirring and allow to stand for 
15 minutes. Filter through a weighed Gooch crucible, pre- — 
pared with a medium thick mat of asbestos, or an Alundum 
crucible using suction if necessary to aid filtration. Wash 
the residue in the crucible until the washings are colorless, 
dry in air at room temperature until the odor of carbon bi- 
Sulphide has almost disappeared, and then for 1 hour at 105° 
to 110° C. Cool, weigh, and calculate percentage of insolu- 
ble material. In this method if Trinidad asphalt is present 
some of the fine mineral matter may pass through into the ex- 
tract. This can be determined by evavorating the extract, 


540 Bituminous Paints 
denne. ——————e 


burning off the bituminous matter, and weighing the ash ob- 
tained. 

(3) Weigh the sample into a paper thimble and extract ina 
Soxhlet or other suitable extractor. . 

Examination of insoluble matter—The insoluble matter 
(filler, pigment, free carbon) is examined as in the case of oil 
paints, except as follows: 

(1) Fibrous Filler —Examine mior once pia for mineral 
wool, rag fibers, jute, paper pulp and asbestos. 


(2) Free carbon from coal tar compositions, m presence of 
mineral matter containing water of crystallization.—W hen the 
filler is asbestos, this method gives satisfactory results. Hx- 
tract about 5 grams of the sample as in ‘‘C’’ and weigh the 
residue of carbon and asbestos. Now burn off the carbon and 
weigh. Increase this weight by 14 per cent to compensate for 
water of crystallization driven off from the asbestos. Calcu- 
late percentages of free carbon and asbestos. 


(3) For mixtures of free carbon with asbestos and clay.— 
The following method has been suggested but has not as yet 
been thoroughly investigated: Extract about 5 grams of the 
sample as in ‘‘C’’ and weigh the residue. Ignite the residue 
in a crucible for seven minutes in a current of dry carbon diox- 
ide (using a Rose crucible cover) with a flame about 20 cm. 
high, or in a platinum crucible with a tightly fitting cover in a 
muffle at between 950° and 975° C. for seven minutes. Cool 
and weigh. The loss in weight is water of crystallization from 
the filler. Now burn off the carbon, cool, weigh and calculate 
the loss in weight as free carbon. 


(D) Nonvolatile Vehicle: 

Saponifiable or fatty matter may be determined by either of 
the following methods. If no pigment or filler is present, the 
original material may be taken. If pigment or filler is pres- 
ent, it should be removed as in (C) and the extract containing 
the nonvolatile vehicle or base should be evaporated to a small 
volume over a steam bath. 

(1) The following method is essentially that given in ‘‘ As- 
phalts and Allied: Substances’’—1920, by Herbert Abraham. 

Weigh 5 grams of the original material (or take the evapor- 
ated extract from 7.5 grams of material obtained as in (C), 
and dissolve in 50 ce. of benzol using heat, if necessary, to aid 


Bituminous Paints — «541 
ne a 
solution. Add 5 ce. of dilute nitric acid (1:1) and boil under 
a reflux condenser for one-half hour to decompose any metallic 
soaps (7. e., driers, etc.). Add 150 cc. of water, boil under a _ 
reflux condenser, then transfer to a separatory funnel, draw 
off the aqueous layer, and repeat extractions with water until 
all metals are removed. 


To the benzol solution add 30 cc. of a saponifying liquid 
made by dissolving 100 grams of anhydrous potassium hy- 
droxide in 500 ce. of 95 per cent ethyl alcohol and diluting to 
1,000 ee. with 90 per cent benzol, and boil under a reflux con- 
denser from one-half to one hour. 


Pour the mixture while still warm into a separatory funnel 
containing 150 cc. of boiling water and 25 cc. of a 10 per cent 
solution of potassium chloride. Add 250 ce. of benzol, shake 
vigorously, and allow the funnel to rest quietly in a warm 
place until the solvent separates. (If an emulsion forms which 
refuses to separate on standing, add 200 ec. of benzol and 100 
ec. of 95 per cent ethyl aleohol and stand in a warm place over 
night). Usually three layers are obtained. Draw off the 
aqueous solution of the soaps as completely as possible and 
decant the benzol layer leaving the intermediate layer in the 
funnel. 7 


Extract the aqueous soap solution with 200 ec. portions of 
benzol until the benzol extract is colorless. 


Combine the benzol extracts with the layer obtained from 
the funnel and extract with 100 ce. portions of 50 per cent 
ethyl aleohol. Add the alcohol extracts of the benzol layer to 
the intermediate layer in the separatory funnel and extract 
with benzol until the benzol extracts are colorless. 

Combine the benzol extracts, evaporate, dry at 105° C., and 
weigh as unsaponifiable. 

Combine the aqueous soap and alcohol extracts and acidify 
with dilute hydrochloric acid, warm, and extract with benzol. 
Evaporate the benzol extract, dry at 100° C. and weigh as 
saponifiable. | 

(2) The following method (B. S. Circular 104, Recom- 
mended Specifications for Asphalt Varnish) is ‘more rapid 
and avoids troublesome emulsions. It has not been tried on 
compositions containing very soft petroleum asphalts, Trini- 
dad and Bermudez asphalt, or resins, but it gives satisfactory 


542 Bituminous Paints 


results on mixtures of fatty oil with hard petroleum asphalts, 
gilsonite, wurtzelite pitch, and manjak. 

Weigh about 5 grams of the material into a wide-mouthed 
flask (or take the evaporated extract from 7.5 grams of ma- 
terial obtained as in (C), add 50 ce. of benzol and 5 grams of 
silica sand, and heat under a reflux condenser on a steam bath 
until the material is entirely dissolved. Add 25 ce. of a half 
normal alcoholic caustic potash solution, and 25 ec. of de- 
natured alcohol, and continue boiling under the reflux con- 
denser for one hour. Remove the condenser and evaporate 
the solution to dryness. 

Add to the residue in the flask 50 ee. of distilled water and 
heat until the residue is disintegrated. Filter the water solu- 
tion of the soaps. Repeat this operation with 25 ee. portions 
of water until the residue is completely ecto and the 
wash water is clear and colorless. 

Combine the filtrates (the soap solution ue washings), 
acidify with hydrochloric acid, and heat until the fatty acids 
and any emulsified asphalt separate and rise to the top, and the 
water below is clear. 

Cool, transfer to a separatory funnel, and extract three 
times with 50 ce. portions of ether. Combine the ether ex- 
tracts and wash with water until free from acid. Filter the 
ether extracts through paper into a beaker and wash the resi- 
due on the paper with ether until the washing runs through 
colorless. EKivaporate the ether solutions to dryness. 

Add 15 ee. of 95 per cent ethyl aleohol to the residue in the 
beaker and warm on the steam bath. Cool to room tempera- 
ture and filter through paper into a tared flask or dish. Re- 
peat this operation with 10 ec. portions of 95 per cent ethyl 
alcohol until the aleohol remains colorless. Finally wash the 
residue on the paper with 95 per cent ethyl aleohol until the 
washings run through colorless. 

Evaporate to dryness on a steam bath and heat for an hour 
in an oven at 105° C. (221° F.). Cool and weigh. From the 
weight of the residue in the flask and the weight of the orig- 
inal sample calculate the precentage of fatty matter. 

(Sometimes the residue obtained after saponification and 
the evaporation of the benzol and alcohol from the saponify- 
ing mixture is not completely disintegrated by boiling with 
water. In that case, extract with water until nothing further 


Bituminous Paints 543 
nS SS Sn Rn RS ER PE SS SS SE SES SEER EAU LE TEESE! 
dissolves and then dry. Dissolve in benzol, using heat if nec- 
essary, and wash the benzol solution several times with water. 
Heat the washings until the odor of benzol has disappeared 
and add to the soap solution before acidifying). 


Examination of Saponifiable—The saponifiable obtained as 
above may be separated into fatty and resin acids by method 
as on page 451 and may be tested for rosin and fatty acid 
pitch (Test 37b) ‘‘ Asphalt and Allied Substances’’ by Her- 
bert Abraham—1920. 


Examination of Unsaponifiable—The unsaponifiable should 
be tested for melting point and fixed carbon. In case the 
sample contains no pigment, filler, or saponifiable these tests 
should be made on the nonvolatile obtained as in (A) or in the 
residue from distillation as in (B). 

For asphaltic materials determine the melting point by the 
‘Standard Method of Test for Softening Point of Bituminous 
Materials Other Than Tar Products’’—D. 36-21, A. 8S. T. M. 
Standards, 1921, page 739—(Ring and Ball Method). 

For tar products determine the melting point by the ‘‘Stand- 
ard Method of Test for Softening Point of Tar Products’’— 
D. 61-20, A. S. T. M. Standards, 1921, page 743—(Cube in 
Water Method.) 

For tar products having melting points above 77° C, (170.6° 
F.) use Cube Method in Air—‘‘Asphalts and Allied Sub- 
stances,’’ by Herbert Abraham—1920, page 516. 

Determine fixed carbon on asphaltic materials by method 
given in Journal of American Chemical Society, 1899, Vol. 21, 
page 1116, or ‘‘ Fixed Carbon in Bituminous Materials, Its De- 
termination and Value in Specifications,’’ by L. Kirschbaum, 
Hng. Contr. 39, 172 (1913). The fixed carbon obtained from 
common asphaltic materials is as follows: 


RIO SASPOAIT 65. b ce wwe ee ae elblnes 12. to 14 per cent 
MOT AOA BHNALL . is.0 cece cc's vole ao v's wes 8 914 to 18 per cent 
ERMA OPEC go ujs cos cs ip ns bois 8 es wei ee 15 to 22 per cent 
ETL Ceo wie. ccpieie au woos 4 o's cee © oe + 8s whe 13 ~=to 16 per cent 
MEMES ., ie ck Fe ees hs ge ve wines eae 10 to 138 per cent 
EME ar Wiese we eek eee ge 14 ~=to 20 per cent 
IEEE RIALS Ss ss ease ea ova ass eels Oh eee ls 15 to 25 per cent 
RTE Biome te 6 8 2 gs Lh walla Oe Re aie Boe 30 ~=6to 55 per cent 


(i) Tests for the Differentiation of Asphaltic and Coal Tar 
Pitch: 7 


Owing to the prejudice of the buying public against coal tar 


544 Bituminous Paints 

paints and cements, brought about by the use of materials of 
poor quality made from coal tar materials, and the fact that 
some dealers in asphaltic materials are using these failures as 
selling arguments, the analyst is often called upon to prove 
the presence of coal tar materials other than thinners in 
asphaltic products and vice versa. 


The following tests are useful for this purpose: 


(1) Color of solution of nonvolatile in benzol—Coal tar 
materials usually give a solution with a yellowish or greenish 
brown fluorescence. Asphaltic materials give a brown solution 
without fluorescence. The presence of oily constituents in 
some asphalts may at times give a fluorescence that might 
be mistaken for that obtained from coal tar materials. Wood 
pitches may also give a slight fluorescence. 


(2) Free Carbon—The presence of free carbon indicates 
the presence of coal tar or coal tar pitch. 


(3) Distillation T’est—Weigh into an iron or copper distill- 
ing retort 100 grams of the material under examination. Heat 
very slowly until distillation begins and then distill off the 
thinner at the rate of about one drop a second. Usually 
around 200° CG. a point will be reached where the distillate will 
stop coming over and the temperature will tend to drop. At 
this point the thinner is usually all removed. Change the re- 
ceiver and continue distillation so as to crack or destructively 
distill the bituminous material until the temperature reaches 
360° C. Note the character of the distillate. Asphaltic ma- 
terials usually give liquid distillates of a brown or reddish 
brown color. Coal tar materials usually give solid distillates 
of orange or reddish color or liquid distillates from which 
crystals tend to separate. The character of distillates from 
mixtures of the two materials varies. The presence of fatty 
oil is recognized by the odor of acrolein. 

The following tests are made on the cracked distillate: 

(a) Specific Gravity of Cracked Distillate at 25° C.— 
Cracked distillate or asphaltic materials—O.74 to 0.87. Coal 
tar materials—0.98 to 1.07. Cracked fatty oils lowers the 
specific gravity. 3 

(b) Sulphonation with 38 N H,SO,. _ 

The following amounts of residue are usually obtained: 


Bituminous Paints a. 545 


SITE DIACCTIAIS. . 05 ce ete e ce eeess 0 to 10 per cent 
OS Se el 0 to 15 per cent 
OO CNC a min. 80 per cent 
ME TICCNCS oo. cs oe ct wc ec eet eee eee Oto 5S per cent 
mati Acid bitches and Fatty Oils............. Oto 5 per cent 


(c) Soluble in Dimethyl Sulphate.—This test may be used 
but with caution owing to its unreliability in the case of small 
amounts of either material. 

The distillates from coal tar materials are usually com- 
pletely soluble in dimethyl sulphate, while those from asphal- 
tic materials are about 85 per cent insoluble. 


(d) Anthraquinone Test.—Melt the distillate if solid or if 
it contains solid particles and take about 5 ce. for examination. 
Cool and add 10 ec. of absolute ethyl alcohol and allow to stand 
until the solids separate. Decant the liquid and dry the solids. 
Dissolve in 45 ce. of glacial acetic acid and boil under a reflux 
condenser for 2 hours. Add drop by drop to the boiling solu- 
tion, a solution of 15 grams of anhydrous chromic acid dis- 
solved in 10 ce. of glacial acetic acid and 10 cc. of water. Boil 
under reflux condenser for two hours, allow to cool and add 
400 ee. of cold water, and filter off the precipitated anthra- 
quinone. The crystals of anthraquinone are washed with hot 
water, then a hot 1 per cent solution of NaOH, and then with 
hot water. The residue is dried and weighed and the per- 
centage of anthracene calculated. From 0.25 to 0.75 per cent 
of anthracene is found in coal tars, and correspondingly larger 
amounts in coal tar pitches. 

A qualitative test to identify the crystals consists in boiling 
them with zine dust and caustic soda solution, whereupon an 
intense red colored solution (Alizarin) is obtained, which de- 
colorizes in contact with the air. 

This test will serve to identify coal tar materials in asphalt 
compositions. 

(4) Diazo Reaction—devised by E. Graefe—‘‘ Distinction 
between Lignite Pitches and Other Pitches,’’ Chem. Zeit. 30— 
298—(1906), serves to distinguish those bituminous sub- 
stances containing phenolic bodies from those not containing 
them, as asphalts. It should be made on the original bitumin- 
ous substance. In the absence of coal tar materials, this test 
will establish the presence of wood tars and pitches in asphal- 
tic mixtures especially with a positive Liebermann Storch 
reaction. 


546 Bituminous Paints 


(F) Physical Tests: 

While the foregoing tests will give some information about 
the composition and quality of these materials, and their suit- 
ability for the purpose intended, the following physical tests 
are at times more valuable for determining the adaptability of 
a material for a particular use. 


(1) Time of drying or setting on prepared roofing, metal, 
concrete, ete. 

(2) Heat test at 140° F. 

(3) Exposure test outdoors at angle of 45° to the south for 
periods varying from one week to a month. 

(4) Baking test. 

(5) Toughness. 

(6) Working Properties. 
) Resistance to water, lubricating oil, and acids. 
(8) Heat test on smoke stack paint at 410° F. 
) Adhesion tests. 


Analysis and Specifications for Roof Coatings.—The Fed- 
eral Specifications Board of the U. 8S. Government has recently 
issued Specification No. 424, which is not yet available in 
printed form. This specification covers the purchase of as- 
phalt fibrous roof coatings intended for the repair and coat- 
ing of asphalt and metal roofing, and for application to con- 
crete, masonry, and steel structures as a damp-proof and 
protective coating over a priming coat of asphalt primer. 
Believing that this specification, together with the methods 
of test, will be of general interest to readers of this chapter, 
the essential details of the specification are given below. 


The coating shall consist of asphaltic materials, with or 
without fatty oils, thinned with a volatile solvent to a heavy 
brushing consistency, and asbestos fiber. 


Condition in Container.—The roof coating must be a smooth, 
homogeneous mixture. It must not separate or liver in the 
container. 3 


Consistency.—lt shall be of a heavy brushing consistency 
to insure a film of appreciable thickness and yet not so stiff 
as to prevent easy application with a 3-knot roof brush at 
the rate of approximately 1 gallon per 50 square feet over 
asphalt roofing. : 


Non-volatile Matter.—The roof coating shall yield not less 


Bituminous Paints 547 
$$ eee 


than 60 per cent non-volatile matter when 10 grains are neated 
in an oven at 105° C. (221° F.) for 24 hours. - | 


Asbestos Fiber—The roof coating shall contain not less 
than 5 per cent and not more than 15 per cent. of asbestos 


fiber. None of the asbestoss fiber shall be less than Ye inch 
in length. 


Lime of Setting—Brushed on prepared roofing and metal 
at the rate of 1 gallon per 50 square feet and exposed in the 
laboratory, the coating shall set to a tough plastic coating 
free from stickiness within 24 hours. 

Behavior at 60° C. (140° F.).—When brushed on prepared 
roofing at the rate of 1 gallon per 50 square feet and dried 
for 72 hours and then exposed to a temperature of 60° C. 
(140° F.) for 5 hours the coating shall not slip or sag and shall 
not be absorbed into the roofing. | 


Loughness——When the test piece. from previous test has 
cooled to 25° C. bend quickly over a mandrel 10 mm (2/5 inch) 


in diameter. The coating shall not crack or flake from the 
roofing. 


METHODS OF TESTING 


Condition in Container—Open the container when received 
at the laboratory and examine its contents. The material 
must be a smooth, homogeneous mixture and there must not be 
any separation, caking or livering. 


Non-volatile Matter.—Weigh about 10 grams of the sample 
in a weighed flat-bottom metal dish about 8 em in diamter, 
or in a friction top can plug. Heat the dish with its contents 
im an oven maintained at 105° C. (22 Tee ee ea Go ee 1s) 
for 24 hours, cool and weigh. From the weight of the residue 
left in the dish and from the weight of the original sample 
taken compute the percentage of nonvolatile matter. 


Asbestos Fiber—Weigh from 2 to 5 grams of the coating 
and transfer to a small beaker. Add 25 to 50 ce of carbon 
bisulphide, stir until thoroughly mixed and allow to stand 
for 15 minutes. . 

Filter the solution through a weighed Gooch crucible pre- 
pared with a medium thick mat of paper pulp or a paper 
‘dise, using suction if necessary to aid filtration. Wash the 
residue in the crucible with cold carbon bisulphide until the 
washings are colorless, dry the crucible with its contents 
in air at room temperature until the odor of carbon bisulphide 
has almost disappeared, and then for 1 hour in an oven at 
100 to 105° C. (221° F.), cool and weigh. From the weight 


548 Bituminous Paints 


of the insoluble matter in the crucible and the weight of the 
sample taken compute the percentage of the matter insoluble 
in carbon bisulphide and consider it as asbestos. Separate 
the layer of insoluble matter obtained from the mat or disc 
in the crucible and examine portions of it under the micro- 
scope in order to determine the length of fiber and the presence 
of material other than fibrous asbestos. Ignite also a weighed 
portion of the insoluble matter to a red heat for one-half hour, 
cool and weigh. The residue obtained shall be not less than 
80 per cent. 

Time of Setting.—Brush the coating at a rate of approxi- 
mately 1 gallon per 50 square feet on asphalt saturated felt 
and clean metal and allow to dry in the laboratory. Test the 
coating at points not less than 272 cm (1 inch) from the top 
by touching lightly with the finger. The coating is considered 
to have set throughout to a tough plastic mass free from sticki- 
ness when gentle pressure of the finger does not move the 
coating and none of it adheres to the finger. 

Behavior at 60° C. (140° F.).—Prepare test pieces on as- 
phalt saturated felt as in previous test and allow to dry for 
79 hours in a well-ventilated room. Suspend the test pieces 
vertically for 5 hours in an oven maintained at 60° C. (140° 
F.). On examination at the end of this period the coating 
shall not show blistering, sagging, or slipping of more than 
one-quarter of an inch and shall not be absorbed into the felt. 

Toughness.—Cool the test pieces from above to room 
temperature and bend quickly over a mandrel 10 mm (2/0 
inch) in diameter. In bending, the felt should be next to 
the mandrel. The coating shall not crack or flake from the 
roofing. 

Testing Automobile Black Baking Enamels.—An outline of 
some of the tests used by a committee of the subdivision on 
black baking enamels of the Society of Automotive Engineers, 
in co-operative work carried on during the past three years, 
is presented below. It is believed that in general these 
methods will give information of value in determining the 
relative properties of black baking enamels. 


Consistency.—‘‘The consistency shall be determined by re- 
ducing the Enamel with Mineral Spirits to a degree that when 
liberally poured over a No. 22 U.S. Standard Gage Steel panel 
314 inches wide by 12 inches long at a temperature of 80 deg. 
Fahr., and allowed to drain in a vertical position for 15 
minutes and properly baked will have a film thickness of 


Bituminous Paints 549 
a i a 
between 0.0008 and 0.0010 inches, measured 6 inches from the 
top of the panel. 

‘«The panel shall be cleaned to a bright surface by sanding 
with 7/0 waterproof paper and washing with benzol to remove 
rust. 

‘The thickness of the film shall be determined by the micro- 
scopic method, focusing to top and bottom of film. 

‘‘The results shall be reported in parts of thinner to parts 
of enamel required to give specified thickness. 

‘‘The viscosity of the thinned enamel is to be taken also 
in a Universal Saybolt Viscosimeter at 80° F. to compare this 
property with the film thickness. 

‘“‘The Specific Gravity of the thinned sample at 80° F. shall 
be determined by Westphal Balance. 


Baked Panels —‘‘In order to determine the correct baking 
time, three or more panels of the enamel when applied as 
described above shall be baked at 400° F. This temperature 
is very important and should be carefully watched. The size, 
type, kind of heat, and ventilation of baking oven should be 
reported. One of the panels shall be removed from the oven 
at the end of each of the following baking periods—(a) 60 
minutes, (b) 90 minutes, and (c) 120 minutes. The oven shall 
be at temperature when panels are put in and the time taken 
immediately the panels are put into the oven. These panels 
Shall stand over night after baking and then be tested as 
described below: 

(a) Appearance: 

‘“The appearance shall be determined on glass panels of the 
same size as the steel panels. They shall be prepared in the 
Same manner as the steel panels. The results shall be re- 
ported as shown on the log sheet. 

(b) Hardness: 


‘“‘The hardness shall be determined by the Gardner Pencil 
Test method, reporting the greatest pencil hardness that will 
not scratch the surface. 


(ce) Elasticity: 
‘“The elasticity of the film shall be determined by rapidly 


bending each panel 180° over a rod 14 inch in diameter at 
the center and noting the cracking at the bend when examined 


550 Bituminous Paints 


under a shaded light. Report temperature and humidity at | 
the time of making the bend test. | 


(d) Kerosene Softening: 


‘“The enameled panels shall be immersed for 24 hours in 
kerosene at room temperature. The hardness immediately 
after removal shall be determined by the Gardner Pencil Test, 
reporting the greatest pencil hardness that will not scratch 
the surface. | 

Chemical Composition: 


‘“The enamels shall be analyzed for: 


(a) Pigment 
(b) Ash 
(c) Non-Volatile Content 


‘The pigment shall be determined by diluting liberally with 
benzol, settling and filtering or centrifuging, and reporting 
pigment in per cent by weight. 

‘The non-Volatile matter shall be determined by drying a 
sample of from 1.5 to 3.0 grams in a pint friction-top ean lid 
in an oven for 5 hours at 115 to 120° cent. ; 


Exposure Test: 


‘The test panels are to be of automobile sheet or strip steel 
corresponding to hood and fender stock. The panels shall be 
31% inches wide by 12 inches long by 0.035 inches thick. 

‘“Three test panels of each enamel are to be furnished using 
a film thickness of 0.0008 to 0.0010 inches measured 6 inches 
from the top of the panel after baking. The baking time on 
each panel shall be as directed above. 

‘“The panels for the exposure tests shall be labeled as indi- 
cated so that each panel may be properly identified. The char- 
acters should be made with a cellulose nitrate material on a 
sandpapered spot so that they will not rub off or fade out. 

‘‘The exposed panels are to be examined for: (a) lustre; 
(b) general appearance; (c) rusting; (d) adhesion; (e) 
checking.”’ 


‘CHAPTER XXXI 


EXAMINATION OF TURPENTINE AND MINERAL SPIRITS 


The standard specifications of the A. 8S. T. M. for these 
materials are presented in the latter part of this chapter. 
Some special methods of testing mineral spirits are included 
below. With this latter product less uniform grading is 
found in commercial practice than with turpentine. For this 
reason manufacturers of paint and varnish often experience 
considerable difficulty in securing uniform and standard types 
of mineral spirits for their work. Therefore, in addition to 
the test prescribed in the specifications referred to, it is well 
for the chemist to make a study of the evaporative value of 
various grades of mineral spirits submitted. For this purpose 
a good exterior and a good interior varnish base may be 
selected, heated, and thinned with about an equal quantity by 
weight of mineral spirits of the grades being tested. The 
varnishes may then be applied to weighed glass plates which 
should be re-weighed every fifteen minutes for a period of two 
hours. The loss in volatile is then reported. Mineral spirits 
having large quantities of heavy, non-volatile ends will readily 
be noticed. The body of the varnishes and the brushing, flow- 
ing and leveling properties should also be ascertained by 
further tests. 


Solvent Properties —It is also advisable to make a test to 
determine the solvent properties of the mineral spirits, and 
for this purpose it is customary to use varnish bases as re- 
ferred to above, thinning down with equal parts by weight of 
the mineral spirits being tested. The reduced samples are gen- 
erally placed in 4 oz. oil bottles and inspected for a period 
of 10 to 12 days to watch for the development of suspended 
matter, turbidity or other precipitated products due to lack 
of solvent properties of the thinner. Distillation of a sample 
of the mineral spirits and examination of the various frac- 
tions for solvent properties often gives much information of 
value. 

One of the most useful materials to include in a test for the 
solvent character of mineral spirits is extremely heavy-bodied 
linseed oil. Apparent solution takes place when such an oil is 
thinned with mineral spirits, but after standing, the oil is often 


BEY Turpentine and Mineral Spirits 
thrown out, showing that the preliminary solution was only of 
a suspension colloid type. The continued addition of incre- 
ments of mineral spirits to a volume of heavy-bodied oil, until 
the precipitation point is reached, will give relative data of al- 
most quantitative character. Since such oils are often used 
in flat finishes which sometimes contain in the liquid portion as 


Begins to cloud Separation occurs 
Thinner a ae 

Oil Thinner Oil Thinner 
Die ee 2 1 3 
E.. ae. Men Re GOES one Heel a) a” 1 8 i: 8 
eae 1a hi ay uate eae Ri ne No cloudiness or separation at any dilution. 
Git 1 | 10 1 | 11 
tae si poled ete ta dan MON ae No cloudiness or separation at any dilution. 
ta : y Pee Me ete gb e pie. 1 a 1 4 
Ki aia 1 3 1 4 
lid hel 1 8 1 10 


high as 75 per cent of mineral spirits, the throwing out of the 
oil would be a very objectionable feature. 


There appears to be a great difference in the action of the 
various brands of mineral spirits with bodied oils, especially 
blown oils. Turpentine usually mixes well in all proportions 
with such oils. When equal portions of the same oil and min- 
eral spirits are mixed, some samples show a turbid and milky 
appearance. As the quantity of thinner is increased the tur- 
bidity increases until separation occurs. While in some grades 
cloudiness occurs even at low dilution, other samples may not 
become turbid until much greater dilutions have been reached. 
Some may remain clear when mixed in practically any propor- 
tion. Where there is only a slight turbidity at first, complete 
separation may occur on standing. The accompanying chart 
shows the dilutions at which cloudiness and oil separation first 
occurred when thinning a very heavy grade of blown and heat- 
treated linseed oil with several commercial grades of mineral 
spirits. Figures indicate parts by weight. 


-- wee 


Turpentine and Mineral Spirits 553 


In making these dilution tests a tall narrow beaker may be 
conveniently used. <A fair idea of the miscibility of the thinner 
may be obtained in the following manner: Weigh out a small 
quantity of bodied oil, say 5 or 10 grams, in the beaker. Then 
add an equal quantity of the mineral spirits to be tested. Stir 
with a glass rod, noting the readiness with which the two 
layers mix. Some samples will show a cloudiness at once, 
which may, however, disappear as the two mix. Others may 
mix perfectly clear. Add successive portions of the thinner, 
stirring after each addition and noting carefully the appear- 
ance, readiness of mixing, etc. Determine the point at which 
a permanent milkiness results. After the addition of one or 
two more portions, part or all of the oil will usually separate 
on standing a short time. 

While the quantity of thinner required to throw out the oil 
may in many cases be far in excess of the proportion ordi- 
narily used, yet in consideration of the fact that the products 
which exhibit the greatest tendency to become turbid are most 
likely to separate on standing, it seems advisable to employ 
only those which stand up best under the dilution test. 


Run Kauri Solubility Test—Another test of importance can 
be made with standardized run Kauri gum such as is used for 
testing the elasticity of varnish. The preparation of this is 
outlined in the specifications for spar varnish in the back of 
this book. The Run Kauri is dissolved in an equal quantity 
by weight of re-distilled turpentine. To 50 ce. of the mixture, 
mineral spirits is gradually added with occasional shaking 
until a cloud forms. An improvement in the test is to use a 
mixture of 100 ce. of the Run Kauri solution and 100 ce. of 
heavy bodied oil, subsequently thinning down a determined 
volume of this mixture with the mineral spirits under exam- 
ination. For this purpose, however, a standard grade of 
heavy bodied oil should be used in every laboratory, otherwise 
different results would be obtained. 

Whether the thinner is derived from an asphaltum base or 
paraffin base petroleum is of little importance so long as it con- 
forms to other requirements. The asphaltum base petroleums 
are said to possess, in general, greater solvent power due to 
the presence of a larger proportion of cyclic hydrocarbons. If 
desired, the proportion of the latter may be estimated com- 


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Turpentine and Mineral Spirits 555 


paratively by the Formolit Reaction (Nastjukoff Test) ).* 
But practical tests, such as those described herein must remain 
the deciding ones in determining the value of a given thinner. 


Sulphur Content.—Another very important observation to 
be made on mineral spirits is the effect of the sulphur content 
upon the color of paints or varnishes in which they are used. 
The white lead test that has in the past been used for this pur- 
pose will not very often disclose the presence of objectionable 
sulphur compounds. The Doctor test is not sensitive and is 
rather difficult to perform. Varnishes, however, which con- 
tain metallic driers, such as lead, in organic solution, will 
rapidly become darkened when thinned with mineral spirits 
containing certain objectionable sulphur compounds. Some 
grades of mineral spirits, for instance, may contain as high as 
1% per cent of sulphur. If this sulphur is in a certain fixed 
form, it may not darken with lead compounds in solution. 
Other grades of mineral spirits, which contain even very small 
traces of sulphur in readily available form, will quickly darken 
organic lead solutions. One test which the writer has used is 
as follows: 7 


Make up a varnish base by fusing 100 grams of rosin 
with five-tenths of a gram of lead oxide. If desired, co- 
balt, manganese, copper and other oxides that are liable 
to be present in cooked varnish, may also be included 
in small amounts. This is then used as the base for 
test. 100 grams of the product is heated and thinned 
down with 100 grams of the mineral spirits to be tested, 
and held at a temperature of about 350° F. for 30 
minutes, preferably in a reflux condenser. Darkening 
will occur with those grades of mineral spirits having 
reactionable sulphur content. 


Probably the most graphic test for sulphur in mineral spirts | 
is the copper strip test. This is made by placing in a carbon 
tube about 15” long and 14” in width, a strip of copper 14” wide 
and 2” long. Sufficient mineral spirits is added to completely 
cover the copper. The tube is then immersed in an oil bath 
which is run up to 350° F. or to such temperature as will cause 
the mineral spirits to boil. The test should be run for a period 


*See Holde-Mueller. Examination of Hydrocarbon Oils and Saponifiable 
Fats, John Wiley & Sons, p. 388. 


556 Turpentine and Mineral Spirits 


of 30 minutes, and the effect on the copper strip observed. If 
only a slight bloom or fluorescence is shown, the mineral spirits 
should be acceptable. If blackening of the strip is shown, the 
mineral spirits should be looked upon as unsatisfactory for 
certain varnishes. This test will show a blackened condition 
of copper if the mineral spirits contains even .04 per cent of 
reactive sulphur. 


It has been proposed to run the copper strip test at a higher 
temperature, keeping the strip in a flask of boiling mineral 
spirits, connected with a reflux for ten minutes and then dis- 
tilling off about 96 per cent of the mineral spirits. 

Distillation Range.—Better control of boiling range by the 
refiner will enable him to deliver a more satisfactory product 
to the consumer. Mineral spirits conforming to Federal 
Specifications (see back part of this volume) while generally 
satisfactory for thinning paste paints, would be of much 
greater value for thinning varnishes if of a narrower range in 
distillation. The Philadelphia Paint Production Men’s Club 
suggests the following range: 


Distillate below 150° C. not over 5%. 
Distillate below 180° C. not less than 50%. 
Distillate below 220° C. not less than 97%. 


A. 8S. T. M. STANDARD SPECIFICATIONS FOR GUM SPIRITS 
OF TURPENTINE AND STEAM-DISTILLED WOOD 
TURPENTINE 


1. These specifications apply both to spirits of turpentine made from gum 
(oleoresin) from a living tree, commonly known as “gum spirits” or “turpen- 
tine” and to steam-distilled wood turpentine, which is distilled with steam 
from the oleoresin within the wood. When ordering under these specifications, 
the purchaser shall specify whether (a) gum spirits of turpentine or (0) 
steam-distilled wood turpentine is desired. 


I. PROPERTIES AND TESTS 

2. Gum spirits of turpentine or steam-distilled wood turpentine shall be 
pure and conform to the following requirements : 

8. It shall be clear and free from suspended matter and water. 

4. The color shall be “Standard” or better. 

5. The odor shall be mild, aromatic and characteristic of the variety of 
turpentine specified and, if desired, shall conform to the odor of the sample 
agreed upon. 

6. Other properties shall be as follows: 


Turpentine aud Mineral Spirits 557 


Maximum Minimum 

eee aVity 15.5° /15.5° Con... cee ye ede. 0.875 0.860 
Buereraverniex At ZOO. . kw kee ce cae 1.478 1.465 
Residue after polymerization with 38 N H,SO,: 

SPENT TCCONG os 6. cc te os sce wesc twee 2.0 eee cape 

peereetave index At 20° CO... . wk cet eee ee 1.500 

Consistency shall be viscous. 

Color shall be straw or darker. 
Initial boiling point at 760 mm. pressure...... 160° C. 1502 C. 
Distilling below 170°C. at 760 mm. pressure, 

Sia eens wigs oe a ale sre el sles cee ie 0 9s eee es 90 


Il. METHODS OF TESTS 
7. The sampling and methods of testing shail be conducted in accordance 
with the Standard Methods of Sampling and Testing Turpentine (Serial 
Designation: D 233) of the American Society for Testing Materials.* 


A.S.T.M. TENTATIVE SPECIFICATIONS FOR 
DESTRUCTIVELY DISTILLED WOOD TURPENTINE* 


1. These specifications apply only to destructively-distilled wood turpentine 
obtained in the destructive distillation of resinous wood. 


I. PROPERTIES AND TESTS 
2. The destructively distilled wood turpentine shall be pure and conform 
to the following requirements: 
3. It shall be clear and free from suspended matter and water. 
4. The color shall be “Standard” or better. 
5. The odor shall be characteristic of destructively-distilled wood turpen- 
tine and, if desired, shall conform to the odor of the sample agreed upon. 


6. Other properties shall be as follows: 
MAXIMUM MINIMUM 


PUMA OTAVILY, 10.0 /1D.5° Goceks ecco case cece 0.875 0.860 
Hemuactiye index at 20° C., D line....... ....... 1.4838 1.463 
Residue after polymerization with 38 N H).SO,: 

Pen e CTI CON (0). ic sve cn 0's ce oe 0 ses ese 2.0 nie A 

Peetrreniye. INGex at 20° ©... 6. sic ce wes cies CALE 1.480 
Initial boiling point at 760 mm. pressure..... iby igs Oe 150° C., 
Distillation below 170° C. at 760 mm. pressure, 

REI AAMT ae oia's bos cv ace Sok Oe eV ac <i s's sae 60 
Distilling below 180° C. at 760 mm. pressure, per 

RE Te APs any 'c ike sos in 605,84 0! 0% so 8 wale See 0 Seats 90 


-II. METHODS OF TEST 
7. The sampling and methods of testing shall be conducted in accordance 
with the Standard Methods of Sampling and Testing Turpentine (Serial 
Designation: D 233) of the American Society for Testing Materials. 


A. 8S. T. M. STANDARD METHODS OF SAMPLING AND 
TESTING TURPENTINE 


I. DETECTION AND REMOVAL OF SEPARATED WATER 
1. Draw a portion by means of a glass or metal container with a removable 
stopper or top, or with a “thief,” from the lowest part of the container, or by 


* A.'S.T.M. Standards Adopted in 1926 


558 Turpentine and Mineral Spirits 
| a 
opening the bottom valve of the perfectly level tank car. If water is found 
to be present, draw it all out, record the quantity, and deduct it from the 
total volume of liquid delivered. 


¥ Il. SAMPLING 
2. The method of sampling given under (a) shall be used whenever feasible. 
When method (a) is not applicable, method (0b), (c), or (d) shall be 
used according to the special conditions that obtain. 
(a) While Loading Tank Car or While Filling Containers for Shipment.— 
Samples shall be drawn by the purchaser’s inspector at the discharge pipe 
where it enters the receiving vessel or vessels. The composite sample shall 


be not less than 5 gal. and shall consist of small portions of not more than 1 


qt. each taken at regular intervals during the entire period of loading or 
filling. 

The composite sample thus obtained shall be thoroughly mixed and from 
it three samples of not less than 1 qt. each shall be placed in clean, dry, glass 
bottles or tin cans, which shall be nearly filled with the sample and securely 
stoppered with new, clean corks or well-fitting covers or caps. These shall 
be sealed and distinctly labeled by the inspector; one shall be delivered to the 
purchaser, one to the seller, and the third held for check in case of dispute. 

(vb) From Loaded Tank Car or Other Large Vessel.—The composite sample 
taken shall be not less than 5 gal. and shall consist of numerous small samples 
of not more than 1 qt. each taken from the top, bottom, and intermediate points 
by means of a metal or glass container with removable stopper or top. This 
device, attached to a suitable pole; is lowered to the various desired depths, 
when the stopper or top is removed and the container allowed to fill. The 
sample thus obtained is handled as in method (a). 

(c) Barrels and Drums.—Barrels and drums shall be sampled after gaging 
the contents. Five per cent of the packages in any shipment or delivery shall 
be represented in the sample. Thoroughly mix the contents of each barrel 
to be sampled by stirring with a clean rod and withdraw a portion from about 
the center by means of a “thief” or other sampling device. The composite 

sample thus obtained shall be not less than 3 qt., shall consist of equal portions 

of not less than } pt. from each package sampled, and shall be handled as in 
method (a). Should the inspector suspect adulteration, he shall draw the 
samples from the suspected packages. 

(d) Small Containers, Cans, etc., of 10 gal. or Less.—These shall be 
sampled, while filling, by method (a) whenever possible; but in case this is 
impossible the composite sample taken shall be not less than 3 qt. This shall 
be drawn from at least five packages (from all when fewer), and in no case 
from less than 2 per cent of the packages. The composite sample thus taken 
shall be thoroughly mixed and subdivided as in method (a). 


Ill. LABORATORY EXAMINATION 

8 Examine to determine compliance with the specifications. 

4. Fill a 200-mm. perfectly flat-bottomed colorimeter tube, graduated in 
millimeters, to a depth of from 40 to 50 mm. with the turpentine to be ex- 
amined. Place the tube in a colorimeter and place on it or under it a No. 2 
yellow Lovibond glass. Over or under a second graduated tube in the colori- 
meter, place a No. 1 yellow Lovibond glass and run in the same turpentine 
until the color matches as nearly as possible the color in the first tube. Read 


ayer FN 


sa IN eT i A a A ak pall cath Shells) ied “Dg 


Turpentine and Mineral Spirits 559 


the difference in depth of the turpentine in the two tubes. If this difference 
is 50 mm. or more, the turpentine is “Standard” or better. 

5. Determine odor by comparison with the agreed-upon sample which shall 
have been kept in the dark in completely filled well-stoppered bottles and free 
from separated water. In case no agreed-upon sample is available, compare 
with samples of known purity that have been kept in filled stoppered bottles 
in the dark and are free from separated water. 

-6, Determine specific gravity at 15.5 /15.5° C., by any convenient method 
that is accurate within 2 points in the fourth figure. 

7. Determine refractive index at 20° C. with an accurate instrument. When 
the refractive index is determined at any other temperature, the readings 
obtained shall be corrected to 20° C. by adding to or by subtracting from the 
actual reading 0.00045 for each degree Centigrade that the temperature at 
which the determination was made is, respectively, above or below 20° C. 

8. Distillation Apparatus.*—(a) Condenser.—The type of apparatus is 
shown in Fig. 194, or may be the apparatus described in the Tentative Method 


we 


7-7 Se: 


——— 


FIGURE 194 
Distillation Apparatus. 


* The flask, condenser, shield, ring support and hard asbestos board, gas 
burner or electric heater, described in the Tentative Method of Test for 
Distillation of Gasoline, Naphtha, Kerosene and Similar Petroleum Products 
(Serial Designation: D 86-26 T) of the American Society for Testing Ma- 
terials, Proceedings, Am. Soc. Testing Mats., Vol. 26, Part I (1926), which are 
essentially the same as the equipment herewith described, may be employed 
in the distillation test wherever it is available. 


560 Turpentine and Mineral Spirits 


aaa, 


of Test for Distillation of Gasoline, Naphtha, Kerosene and Similar Petroleum 
Products (Serial Designation: D 86-26 T) of the American Society for 
Testing Materials,* substituting for the thermometer there described an 
immersed thermometer, such as is described below. 

(b) Flask—Comparable results can be obtained only by using flasks of 
the same dimensions. The distilling flask used shall be the standard Engler 
flask, as used for petroleum distillation, having the following dimensions: 
Diameter of bulb, 6.5, cm.; cylindrical neck, 15 cm. long, 1.6 cm. internal 
diameter ; side or vapor tube, 10 em. long, 0.6 cm. externa] diameter, attached 
to neck at an angle of 75 deg., so that when the flask contains its charge of 
100 ec. of oil the surface of the liquid shall be 9 em. below the bottom of the 
junction of the side tube and neck. 

(c) Support for Flask.—Support the flask on a plate of asbestos 20 cm. in 
diameter, having an opening 4 cm. in diameter in its center, and heat with 
an open flame. Surround the flask and burner with a shield to prevent 
fluctuation in the temperature of the neck of the flask. Or, support the flask 
in a metal cup, 15 to 20 cm. in diameter, containing high-boiling mineral oil 
or glycerin and fitted with a concave cover having in the center a circular 
opening 54 to 6 em. in diameter. In all cases take the necessary precautions 
to prevent fluctuation in temperature in the neck of the flask. 

(d) Thermometer.—The thermometer used for turpentine distillation shall 
conform to the following specifications: 

It shall be graduated from 145 to at least 200° C. in 0.2° intervals. Length, 
bottom of thermometer to 175° C. mark, not more than § nor less than 6.5 cm. 
Length, top of bulb to 145° C. mark, not less than 1.5 cm. Length, 145 to 175° 
C. mark, not more than 6 cm. Thermometers graduated above 200° C. may be 
used, provided they also comply with the foregoing requirements. 

The thermometer shall be made of suitable thermometric glass and thor- 
oughly annealed, so that the scale errors will not increase after continued 
heating. 

The thermometer shall be filled above the mercury with an inert gas, with 
sufficient pressure above the mercury column to prevent breaking of the 
column. It shall have a reservoir at the top, so that the pressure will not 
become excessive at the highest temperature. 

Every fifth graduation shall be longer than the intermediate ones, and 
the marks shall be numbered at each interval of 5° C. The graduation marks 
shall be clear-cut and fine and the numbering clear-cut and distinct. 

The error at any point on the scale shall not exceed + 0.5° C. when tested 
for total immersion of the mercury column. é 

(e) Receiving Cylinder.—Collect the distillate in an accurately graduated 
50 or 100-ce. cylinder. The so-called normal or precision cylinder of 50 cc. 
capacity, having an internal diameter of 1.5 cm. and graduated in 0.2 ce. is 
preferred. If a cylinder with larger inside diameter is used, a pasteboard 
cover should be placed over the top and surround the condenser tube. 

9. Operation.—Place 100 cc. of the turpentine and several small pieces of 
pumice (or glass) in the distilling flask, fit the thermometer so that the top 
of the mercury bulb is level with the bottom of the side tube, and the 175° C. 


* Proceedings. Am. Soc. Testing Mats., Vol. 26, Part I (1926); also 1926 
Book of A.S.T.M. Tentative Standards. 


Th Ree 


gars rick ae! 


Turpentine and Mineral Spirits 561 


mark is below the cork. Place the flask in position on the asbestos board or 
oil bath and connect with the condenser. Apply the heat cautiously at first, 
and, when distillation begins, regulate the heat so that the turpentine distills 
at the rate of not less than 4 nor more than 5 cc. per minute (approximately 
two drops per second). The initial boiling point is the thermometer reading 
at the instant when the first drop falls from the end of the condenser. Dis- 
continue distillation when the temperature reaches 170° C., or an equivalent 
thereof, depending on the atmospheric pressure, as described in Section 10; 
let the condenser drain and read the percentage distilled. 

The percentage distilled below successive selected temperatures and the 
temperature at which each successive 10 cc. distills may also be determined, 
if desired, making the necessary correction of the temperature for variations 
in atmospheric pressure. 

10. Correction for Variation in Atmospheric Pressure.—Since distillation 
results are comparable only when obtained under exactly the same pressure 
conditions, turpentine shall be distilled at that pressure which, at room 
temperature, is equivalent to a pressure of 760 mm. of mercury at O° C., 
Whenever the atmospheric pressure after correcting to O° C. is other than 


CORRECTION TO BAROMETER READINGS.! 


(From Circular F, Instrument Division, Weather Bureau, U. S. Department of 


Agriculture.) 
Texapera- Observed Reading of Barometer, mm. 
ture, 
deg. Cent. 

650 | 660 | 670 | 680 | 690 | 700 | 710 | 720 | 730 | 740 | 750 | 760 | 770 | 780 
15.0 1.56 | 1.59 | 1.61 | 1.64 | 1.66 | 1.69 | 1.71 | 1.74 | 1.76 | 1.78 | 1.81 | 1.83 | 1.86 | 1.88 | 1.91 
16.0 1.67 | 1.69 | 1.72 |.1.75 | 1.77 | 1.80 | 1.83 | 1.85 | 1.88 | 1.90 | 1.93 | 1.96 | 1.98 | 2.01 | 2.03 
17.0 1.77 | 1.80 | 1.83 | 1.86 | 1.88 | 1.91 | 1.94 | 1.97 | 1.99 | 2.02 | 2.05 | 2.08 | 2.10 | 2.13 | 2.16 
18.0 1.88 | 1.91 | 1.93 | 1.96 | 1.99 | 2.02 | 2.05 | 2.08 | 2.11 | 2.14 | 2.17 | 2.20 | 2.23 | 2.26 | 2.29 
19.0 1.98 | 2.01 | 2.04 | 2.07 | 2.10 | 2.13 | 2.17 | 2.20 | 2.23 | 2.26 | 2.29 } 2.32 | 2.35 | 2.38 | 2.41 
20.0 2.08 } 2.12 | 2.15 } 2.18 | 2.21 | 2.25 | 2.28 | 2.31 | 2.34 | 2.388 | 2.41 | 2.44 } 2.47 | 2.51 | 2.54 
21.0 2.19 | 2.22 | 2.26 | 2.29 | 2.32 | 2.36 | 2.39 | 2.43 | 2.46 | 2.50 | 2.53 | 2.56 | 2.60 | 2.63 | 2.67 
22.0 2.29 | 2.33 | 2.36 | 2.40 | 2.43 | 2.47 | 2.51 | 2.54 | 2.58 | 2.61 | 2.65 | 2.69 | 2.72 | 2.76 | 2.79 
23.0 2.40 | 2.43 | 2.47 | 2.51 | 2.54 | 2.58 | 2.62 | 2.66 | 2.69 | 2.73 | 2.77 | 2.81 | 2.84 | 2.88 | 2.92 
24.0 2.50 | 2.54 | 2.58 | 2.62 | 2.66 | 2.69 | 2.73 | 2.77 | 2.81 | 2.85 | 2.89 | 2.93 | 2.97 | 3.01 | 3.05 
250 2.60 | 2.64 | 2.68 | 2.72 | 2.77 | 2.81 | 2.85 | 2.89 | 2.93 | 2.97 | 3.01 | 3.05 | 3.09 | 3.13 | 3.17 
26.0 2.71 | 2.75 | 2.79 | 2.83 | 2.88 | 2.92 | 2.96 | 3.00 | 3.04 | 3.09 | 3.13 | 3.17 | 3.21 | 3.26 | 3.30 
27.0 2.81 | 2.85 | 2.90 | 2.94 | 2.99 | 3.03 | 3.07 | 3.12 | 3.16 | 3.20 | 3.25 | 3.29 | 3.34 | 3.38 | 3.42 . 
28.0 2.91 | 2.96 | 3.00 | 3.05 | 3.10 | 3.14 | 3.19 | 3.23 | 3.28 | 3.32 | 3.37 | 3.41 | 3.46 | 3.51 | 3.55 
29.0 | 3.02 | 3.06 | 3.11 | 3.16 | 3.21 | 3.25 | 3.30 | 3.35 | 3.39 | 3.44 | 3.49 | 3.54 | 3.58 | 3.63 | 3.68 
30.0 3.12 | 3.17 | 3.22 | 3.27 | 3.32 | 3.36 | 3.41 | 3.46 | 3.51 | 3.56 | 3.61 | 3.66 | 3.71 | 3.75 | 3.80 
31.0 3.22 | 3.27 | 3.32 | 3.37 | 3.43 | 3.48 | 3.53 | 3.58 | 3.63 | 3.68 | 3.73 | 3.78 | 3.83 | 3.88 | 3.93 
32.0 3.33 | 3.38 } 3.43 | 3.48 | 3.54 | 3.59 | 3.64 | 3.69 | 3.74 | 3.79 | 3.85 | 3.90 | 3.95 | 4.00 | 4.05 
33.0 3.43 | 3.48 | 3.54 | 3.59 | 3.64 | 3.70 | 3.75 | 3.81 | 3.86 | 3.91 | 3.97 | 4.02 | 4.07 | 4.13 | 4.18 


1 These corrections apply to a mercurial barometer with brass scale. They can, however, be used fora mercurial 
barometer with glass scale, since the érrors introduced thereby are negligible as applied to the work contemplated in 
_ this circular. For exact correction to be applied to such a barometer see Smithsonian Physical Tables, p. 119 (1914). 
An aneroid barometer should not be relied on. : , . 

For barometer readings below 640 mm. the correction can be interpolated, since the difference at any particular 
temperature for each 10 mm. variation in barometer reading is practically constant. 


760 mm., a correction shall be made. Since alteration of the pressure in the 
distilling system requires rather complicated apparatus, it is simpler to alter 
the temperature observation points to correspond to the prevailing pressure. 

To determine what the atmospheric pressure at the prevaiilng room tem- 
perature, or at the temperature of the barometer, would be at 0° C., read the 
barometer and the thermometer alongside when about to begin distillation. 
Referring to Table above, under the column nearest the observed pressure 
reading and on the line nearest the observed temperature of the barometer 


562 Turpentine and Mineral Spirits 


will be found the correction which must be subtracted from the observed 
pressure reading to obtain the equivalent, or true, reading at 0° C. 


The distilling temperature of turpentine is affected plus (+) or minus 
(—) 0.057° C. for each millimeter variation of the barometer above or 
below the normal 760 mm. at 0°C.* If the barometer reading, after correct- 
ing to 0° C., is below 760 mm., the turpentine will distill at a slightly lower 
temperature than under normal pressure. Therefore, the temperature re- 
corded at the beginning of distillation (and any others observed during the 
course of the distillation) must be corrected to get its equivalent at normal 
pressure, The final temperature observation point (170° C., Section 9) must 
be altered accordingly to get its equivalent at the pressure (corrected to 0° 
C.) at which distillation is made. 


For example, if the barometer reading, after correcting to O° C., is 
750 mm., the correction of the observed initial distilling temperature will be 
0.057 X 10 = 0.6° C. approximately. If the reading of the thermometer when 
the turpentine begins to distill is 155.6° C., the corrected initial distilling 
temperature will be 155.6° + 0.6° = 156.2° C. Furthermore, the temperature 
observation point at end of distillation (170° C. at 760 mm.) must be altered 
to the same extent. Since the turpentine is distilling 0.6° C. below what it 
would at normal pressure, distillation must be discontinued at 0.6° C. below 
the specified limit of 170° C. to determine the percentage distilling below 
170° C, 

If the barometer reading corrected to 0° C. is above 760 mm., subtract the 
temperature correction from the observed thermometer reading to determine 
the initial distilling point, and continue distillation to 170° C. plus the correc- 
tion to determine the percentage distilling below 170° C. 

11. (a) Place 20 ce. of 38 N (equivalent to 100.92 per cent H,SO,) sulfuric 
acid in a graduated, narrow-necked Babcock flask, stopper, and place in ice 
water to cool. Add slowly—from a pipette, 5 ce. of the turpentine to be 
examined. Gradually mix the contents, keeping warm, but being very careful 
that the temperature does not rise above 60° C. When the mixture no longer 
warms up on shaking, agitate thoroughly and place the flask in a water bath 
and heat at 60 to 65° C. for not less than 10 minutes, keeping the contents 
of the flask thoroughly mixed by vigorous shaking for one-half minute each 
time, six times during the period. Do not stopper the flask after the turpen- 
tine has been added, as it may explode. Cool to room temperature, fill the 
flask with concentrated sulfuric acid until the unpolymerized oil rises into 


the graduated neck and centrifuge from four to five minutes at not less than ~ 


1200 r. p. m., or for 15 minutes at 900 r. p. m., or allow to stand, lightly 
stoppered, for 12 hours. Calculate the percentage, note the consistency and 
color, and determine the refractive index (at 20° C.) of the unpolymerized 
residue. 

(b) Reagent for Testing.—In a weighed glass-stoppered bottle (the regu- 
lar 2%-liter acid bottle is of a convenient size) mix ordinary concentrated 
sulfuric acid (sp. gr. 1.84) with fuming sulfuric acid. If the fuming acid 
used contains 50 per cent excess SO,, the ratio of one part, by weight, of the 
former to three-fourths of a part, by weight, of the latter will give a mixture 


* Landolt-Biérnstein Physikalisch-Chemische Tabellen, Ed. 4, Table 127, 
p. 435. 


net ie os aie hw ee 


Turpentine and Mineral Spirits 563 


slightly stronger than the required strength. To determine the exact strength 
of this mixture in terms of H,SO,, weigh exactly, in a weighing pipette of 
about 10 ce. capacity, approximately 20 g. of the acid. Allow it to flow down 
the sides of the neck into a 1000-cc. volumetric flask containing about 200 cc. 
of distilled water. When the pipette has drained, wash all traces of the acid 
remaining in the pipette into the flask, taking precautions to prevent loss of 
SO,, and make up to the mark. Titrate 20-ce. portions, drawn from a burette, 
against half normal alkali. Calculate the concentration in terms of the 
percentage of H,.SO, in the sample taken. 

In the same way determine the percentage of H.SO, in the stock of ordi- 
nary concentrated acid (sp. gr. 1.84). From these data calculate the quantity 
of the latter which must be added to the quantity of mixed acid in the 
weighed bottle to bring it to a concentration, in terms of H,SO,, of 100.92 
per cent. 

After adjusting the concentration by the addition of the ordinary sulfuric 
acid, thoroughly shake the bottle of mixed acid and again determine its concen- 
tration. The allowable variation is + 90.05 per cent H,SO,. Finally as a 
check run a polymerization test on gum turpentine known to be pure. The 
residue should fall below 2 per cent. 


FIGurE 195 
Acid Bottle and Pipette. 


Special precautions must be taken to prevent dilution of this acid by 
the absorption of atmospheric moisture. The arrangement shown in Fig. 195 
is most suitable for storing and delivering measured quantities of this reagent. 


564 Turpentine and Mineral Spirits 


With the three-way stop-cocks A and B in the position shown, acid is 
siphoned into the pipette P, the displaced air passing into R. To empty the 


pipette, A and B are turned to the position shown by the broken lines, air 
passing in at a. The acid adhering to the walls of the pipette dries this air 


so that when it passes into R&R on again filling the pipette there is no accumu- 
lation of moisture in the acid remaining in the reservoir. If such arrange- 
ment is not to be had, the acid should be kept in well-fitting glass-stoppered 
bottles of not more than one-half liter capacity. 


A. 8. T. M. TENTATIVE SPECIFICATIONS FOR 
PETROLEUM SPIRITS (MINERAL SPIRITS) 
1. These specifications apply only to petroleum distillates. 


I. PROPERTIES 

2. The material shall conform to the following requirements : 

(a) Appearance.—It shall be clear and free from suspended matter and 
water. 

(bv) Color.—The color shall be “water white,’ that is, not darker than 
No. 21 Saybolt Chromometer. 

(c) Flash Point.—The flash point shall not be lower than 86° F. (30° C.) 
when tested in the Tag closed tester. 

(d) Blackening.—It shall not blacken or corrode clean metallic copper 
in 30 min. at the boiling point of the spirits. 

(e) Distillation.—The distillate below 266° F. (130° C.) shall not exceed 
5 per cent. 

The distillate below 446° F. (230° C.) shall not be less than 97 per cent. 

(f) Acidity.—The residue after distillation shall be neutral. 


II. METHODS OF TEST 

3. The properties enumerated in these specifications shall be determined 
in accordance with the following methods of test: 

(a) Color—The test for color shall be in accordance with the Tentative 
Method of Test for Color of Refined Petroleum Oil by Means of the Saybolt 
Chromometer (Serial Designation: D 156—23 T) of the American Society for 
Testing Materials.* : 

A fresh aqueous solution of potassium dichromate in distilled water, 
containing 0.0048 g. KyCr.O7 per liter, is approximately equivalent to No. 21 
Saybolt Chromometer. 

(0b) Flash Point.—The test shall be made in accordance with the Standard 
Method of Test for Flash Point of Volatile Flammable Liquids (Serial Desig- 
nation: D 56) of the American Society for Testing Materials.+ 

Blackening—A clean strip of mechanically polished pure Sheet copper, 
about 14% in. (1.8 cm.) in width and 3 in. (7.5 em.) in length, shall be placed 
in a glass test tube about 34 in. (1.9 em.) in width and 18 in. (46 cm.) in 
length. Sufficient of the sample to be tested shall be added to completely 
cover the strip and heated rapidly to boiling. It is most convenient to heat 
higher than the initial boiling point of the mineral spirits. The sample shall 


* Proceedings, Am. Soc. Testing Mats., Vol. 23, Part I, p. 682 (19238) ; also 
1925 Book of A. S. T. M. Tentative Standards, p. 374. 
+ 1924 Book of A.S.T.M. Standards. 


Turpentine and Mineral Spirits 565 


the tube by immersion in an oil bath maintained at a temperature slightly 
be kept boiling for 30 minutes without any actual distillation taking place 
and the copper strip then examined for blackening. <A slight tarnish shall 
be disregarded, but any marked blackening shall be cause for rejection. 


Distillation—The test shall be in accordance wth the Tentative Method 
of Test for Distillation of Gasoline, Naphtha, Kerosine and Similar Petroleum 
Products (Serial Designation D 86 — 26 T) of the American Society for 
Testing Materials.* 


Acidity—The cooled residue from the distillation flask shall be collected 
in a test tube, three volumes of distilled water added, and the tube thoroughly 
shaken. The mixture shall be allowed to separate and the aqueous layer 
removed to a clean test tube by means of a pipette. One drop of a 1-per-cent 
solution of methyl orange shall be added. No pink or red color should be 
formed. 


A. 8. T. M. STANDARD METHOD OF TEST FOR FLASH POINT 
OF VOLATILE FLAMMABLE LIQUIDS 


1. (a) The Tag Closed Tester shall be used for all volatile flammable 
liquids flashing below 175° F. with the exception of products classed as Fuel 
Oil. Determination of the flash point of fuel oil by the Tag Tester is permis- 
Sible, but the Pensky-Martens Tester is to be preferred. aa | 

(b) The Tag Closed Tester shall conform to the following dimensions 
within the limits of tolerances given: : 


DIMENSION. NORMAL, TOLERANCE. 
Depth of water surface below top of 
ae ob eek eee cess 13g5 (27.8mm.) +1, (0.4 mm.) 
Depth of oil surface below top of cup, 
Sy eee’ esis acne ees 1545 (294mm.) +i%, (04mm.) 


Depth of top of bulb of oil thermom- 
eter when in place below top of 


RN MR oo ss Ce ccc a ule co eee 1%, (38.3 mm.) +4 (0.8 mm.) 
Inside diameter of oil cup at top, in 2% (54.00mm.) +0.005 (0.1 mm.) 
Remeemreer On CUD, 2. .... 0... cee e. 68 pe eat 
Diameter of bead on top of cover, in 54, (4.0mm.) +14, (0.4 mm.) 


The plane of underside of cover to be between the top and bottom of 
. the burner tip when the latter is fully depressed. 


(c) The thermometer shall conform to the following requirements. 
These specifications cover a special thermometer graduated in either Centi- 
grade or Fahrenheit degrees as specified, the ranges being —7 to +110° C. 
or +20 to +230° F., respectively. 
Type: Etched stem, glass. 

Ligui: Mercury 
RANGE AND SUBDIVISION’: —7 to 110 Ce in 0.59 ©) or. 20: f0> 230 in 

1 
ToraL LENGTH: 273 to 277 mm. (10.75 to 10,92 in.). 

SteM: Plain front, enamel back, suitable thermometer tubing. Diameter, 
6.0 to 7.0 mm. (0.24 to 0.28 in.). 


* Proceedings, Am. Soc. Testing Mats., Vol. 26; Part I. (1926): also 1926 
Book of A. S. T. M. Tentative Standards, are 


566 Turpentine and Mineral Spirits 


Bus: Corning normal or equally suitable thermometric glass. 
Length, 9 to 18 mm. (0.35 to 0.51 in.). 
Diameter, not greater than stem. . 

DISTANCE TO —7° C. oF +20° F. Line From Borrom oF BULB: 75 to 90 mm. 
(2.93 to 3.54 in.). 

DISTANCE TO 110° C. OR 930° KF, LIne FROM TOP OF THERMOMETER: 25 to 40 
mm. (0.98 to 1.57 in.). 

EXPANSION CHAMBER: TO permit heating the thermometer at least 50° C. 
(90° F.) above highest temperature on scale. 

FILLING ABOVE MERCURY : Nitrogen gas. 

Top FrinisH: Glass ring. 

GrapuATION: All lines, figures, and letters clear cut and distinct. The whole 
degree Centigrade lines or the first and each succeeding 5° F. line to be 
longer than the remaining lines. Graduations to be numbered at each 
multiple of 5° C. or 10° F. 

IMMERSION: 57 mm. or 2% in. The words “S7-mm. immersion” on Centi- 
grade or “2%4-in. immersion” on Fahrenheit thermometers and a line 
around the stem 57.0 mm. or 925 in. above the bottom of the bulb shall 
be etched on the thermometer. 


SPECIAL MARKETING :* “A.S.T.M. P.M. and Tag,” a serial number and the manu- 


facturer’s name or trade mark shall be etched on the stem. 

ScaLE Error: The error at any point of the scale when the thermometer is 
standardized as provided below shall not exceed 0.5° C. or 1° F., respec- 
tively. 

STANDARDIZATION : The thermometer shall be standardized at the ice point 
and at intervals of approximately 20° CG. or 50° F. for 57-mm. or 2%-in. 
immersion and for the following temperatures of the emergent mercury 


eolumn : 
AVERAGE TEMPERATURE OF EMERGENT 
THERMOMETER READING Mercury COLUMN 
Pe Views Bs 70° F. 2c. 70° FB. 
40° GC. 100° F. 31°: C.. ©3867 
TO: C. .150S 40°C. 104° F. 
100° C, 212° F. 48°C. 118° F. 


Case: The thermometer shall be supplied in a suitable case on which shall 
appear the marking: ‘A S.T.M. P.M. and Tag., —7T to +110° CO.” oE 
“A STM. P.M. and Tag., +20 to +230° F.” according to the type of 
thermometer. 


Nore.—For the purpose of interpreting these specifications the following 
definitions apply: 


The total length is the over-all length of the finished instrument. 

The diameter is that measured with a ring gage. 

The length of the bulb is the distance from the bottom of the bulb to the 
beginning of the enamel backing. 

The top of the thermometer is the top of the finished instrument. 

2. (a) If gas is available, connect a \%-in. rubber tube to the corrugated 
gas connection on the oil cup cover. If no gas is available, unscrew the 


* This thermometer is identical with the low-range instrument specified for 
use with the A. S. T. M. Pensky-Martens Closed Tester. 


at) ‘ 
ee oe 


ae 


Turpentine and Mineral Spirits 567 
sl Rita 


test flame burner-tip from the oil chamber on the cover, and insert a wick 
of cotton cord in the burner-tip and replace it. Put a small quantity of 
cotton waste in the oil chamber, and insert a small quantity of signal, sperm 
or lard oil in the chamber, light the wick and adjust the flame, so that it is 
exactly the size of the small white bead mounted on the top of the tester. 

(b) The test shall be‘performed in a dim light so as to see the flash 
plainly. 

(c) Surround the tester on three sides with an inclosure to keep away 
draughts. 

A shield about 18 in. square and 2 ft. high, opens in front, is satisfactory, 
but any safe precaution against all possible room draughts is acceptable. 


Tests made in a laboratory hood or near ventilators will give unreliable 
results. 


(dq) See that the tester sets firm and level. 

(e) For accuracy, the flash-point thermometers which are especially 
designed for the instrument should be used, as the position of the bulb of 
the thermometer in the oil cup is essential. 

3. Put the water-bath thermometer in place, and place a receptacle under 
the overflow spout to catch the overflow. Fill the water bath with water 
at such a temperature that, when testing is started, the temperature of the 
water bath will be at least 20° F. (11° C.) below the probable flash point 
of the oil to be tested. . 

4. Put the oil cup in place in the water bath. Measure 50 cc. of the 
oil to be tested in a pipette or a graduate, and place in the oil cup. The 
temperature of the oil shall be at least 20° F, (11° C.) below its probable 
flash point when testing is started. Destroy any bubbles on the surface 
of the oil. Put on the cover, with flash-point thermometer in place and gas 
tube attached. Light the pilot light on the cover and adjust the flame to 
the size of the small white bead on the cover. 

5. Light and place the heating lamp, filled with alcohol, in the base of 
the tester and see that it is centrally located. Adjust the flame of the 
alcohol lamp so that the temperature of the oil in the cup rises at the rate 
of about 1.8° F. (1° C.) per minute, not faster than 2° F. (1.1° C.) nor 
slower than 1.6° F. (0.9° C.) per minute. 

6. (@) Record the barometric pressure which, in the absence of a lab- 
oratory instrument, may be obtained from the nearest Weather Bureau 
Station. 

(b) Record the temperature of the oil sample at start. 

(c) When the temperature of the oil reaches 9° F. (5° ©.) below the 
probable flash point of the oil, turn the knob on the cover so as to introduce 
the test flame into the cup, and turn it promptly back again. Do not let it 
snap back. The time consumed in turning the knob down and back should 
be about one full second, or the time required to pronounce distinctly the 
words “one-thousand-and-one.” 

(d) Reeord the time of making the first introduction of the test flame. 

(e) Record the temperature of the oil Sample at the time of first test. 

(f) Repeat the application of the test flame at every 1° F. (0.5° C.) rise 
in temperature of the oil until there is a flash of the oil within the cup. 


Do not be misled by an enlargement of the test flame or halo around it 
when entered into the cup, or by slight flickering of the flame; the true 


568 Turpentine and Mineral Spirits 


flash consumes the gas in the top of the cup and causes a very slight 
explosion. 

(g) Record the time at which the flash point is reached. 

(h) Reeord the flash point. 

(i) If the rise in temperature of the oil, from the “time of making the 
first introduction of the test flame” to the “time at which the flash point 
is reached” was faster than 2° F, (1.1° C.) or slower than 1.6° F. (0.9° ©.) 
per minute, the test should be questioned, and the alcohol heating lamp 
adjusted so as to correct the rate of heating. It will be found that the wick 
of this lamp can be so accurately adjusted as to give a uniform rate of rise 
in temperature within the above limits and remain So. 

7. (a) It is not necessary to turn off the test flame with the small regu- 
lating valve on the cover; leave it adjusted to give the proper size of flame. 

(vb) Having completed the preliminary test, remove the heating lamp, 
lift up the oil cup cover, and wipe off the thermometer bulb. Lift out the 
oil cup, and empty and carefully wipe it. Throw away all oil samples after 
once used in making a test. 

(c) Pour cold water into the water bath, allowing it to overflow into a 
receptacle, until the temperature of the water in the bath is lowered to 15° 
F. (8° C.) below the flash point of the oil, as shown by the previous test. 

With cold water of nearly constant temperature, it will be found that a 
uniform amount will be required to reduce the temperature of the water bath 
to the required point. 

(ad) Place the oil cup back in the bath and measure into it a 50-ce. charge 
of fresh oil. Destroy any bubbles on the surface of the oil, put on the cover 
with its thermometer, put in the heating lamp, record the temperature of 
the oil, and proceed to repeat the test as described above in Sections 4 to 6, 
inclusive. Introduce the test flame for first time at a temperautre of 10° F. 
(5.5° ©.) below the flash point obtained on the previous test. 

8. If two or more determinations agree within 1° F. (0.5° C.), the average 
of these results, corrected for barometric pressure, shall be considered the 
flash point. If two determinations do not check within 1° F. (0.5° C.), a 
third determination shall be made and, if the maximum variation of the 
three tests is not greater than 2° F. (1° C.), their average, after correcting 
for barometric pressure, shall be considered the flash point. 

9. Correction for barometric pressure shall only be made in cases of dis- 
pute or when the barometer reading varies more than % in. (13 mm.) 
from the standard pressure of 29.92 in. (760 mm.). When the barometer 
reading is below this standard pressure, add to the thermometer reading 
1.6° F. (0.9° C.) for each inch (25 mm.) of barometer difference to obtain 
the true flash point. When the barometer reading is above the standard 
pressure, deduct 1.6° F. (0.9° C.) for each inch (25 mm.) of barometer 
difference to obtain the true flash point. 


wh 


pais ce Th ali onal ich 


CHAPTER XXXII 
EXAMINATION OF FLAXSEED 


Preparation of Sample.—Sample is quartered until 500 
erams are obtained. In quartering, seed must be poured at 
center of pile to evenly distribute seed and impurities. All 
of the dirt which settles to the bottom must be carefully 
brushed up and added to the pile. Screen the 500 gram sam- 
ple through 10 mesh until about 50 grams remains on the 
sereen. The residue is hand picked and everything other than 
linseed is set aside and weighed with the dust. The clean seed 
obtained at this picking is added to what has passed through 
the 10 mesh screen. The seed is then passed through a 20- 
mesh screen, rubbing the seed around in the screen so as to 
remove any seed attached to it. The under size is collected and 
weighed after the coarse pickings have been added to it. This 
constitutes the first dust. The partially cleaned linseed is then 
reduced to 50 grams in a rifflesampler. This is divided into 
two 25-gram portions which are hand picked separately and 
the impurities weighed separately. All linseed portion, 
whether dried seed or broken seed, is to be put with the lin- 
seed. After corrected calculation, the total impurities are 
obtained. The impurities found in the second picking should 
agree within 60 milligrams. 


Oil in Flaxseed.—A 3-gram sample of the clean seed is 
weighed out and is ground in an agate mortar with an equal 
part of fine sea-sand which has been washed with hydrochloric 
acid. The ground sample is placed in a Soxlet thimble and 
extracted with redistilled ether for three hours. The distillate 
is placed in a weighing dish and the ether is removed by 
evaporation. The residue is then dried for one-half hour at 
103° C., and the oil is weighed. 


Oil in Oil Cake.—A 10-gram sample of undried oil cake is 
placed in a Soxlet thimble and extracted in the same way as 
described under Oil in Flaxseed. 


Water in Oil Cake.—Weigh 5 grams of oil cake and place in 
flask fitted with clean cork. Weigh flask, cork and contents ; 


570 Examination of Flaxseed 


connect with hydrogen generator, and start flow of hydrogen 
at the rate of 2 bubbles per second. Place flask in paraffin 
bath at a temperature of 110° C., and heat in current of hydro- 
gen for two hours. Disconnect tubing, and wipe clean of 
paraffin while hot, with absorbent paper. Cool and draw dry 
air through flask to remove hydrogen. Disconnect, replace 
original cork, and weigh. Loss of weight reported as moisture. 


Protein in Oil Cake.—Protein is found by determining total 
nitrogen by the Kjeldahl method, calculating it to protein. 


Coleman-Fellows Method for Oil Content.—Recent work 
carried out by Coleman and Fellows of the U. 8. Department 
of Ariculture has resulted in the publication of Bulletin 1471 
on the Oil Content of Flaxseed, which presents a new method 
for the rapid determination of the oil content. The paper 
referred to also deals with the sources of variation in the oil 
content and grading of the seed as to oil content. The sources 
of variation are well known and include geographical origin, 
such as Argentina, Canada, North Dakota, ete.; latitudinal 
source within any particular country; total rainfall; and 
regularity of rainfall. In general, Argentine seed contains 
more oil than seed from any of the other places mentioned, but 
poor Argentine seed may contain less than good North Dakota 
seed. In addition to grading seed as to its source the follow- 
ing criteria are, or have been, used or suggested, weight per 
bushel, moisture content, soundness of seed, dockage, color 
and size of seed, and numerical grading which is the compo- 
site of all the above factors. None of the above methods of 
grading has been found to give dependable information as to 
the per cent of oil in flaxseed. 

Wesson observed that the change in the refractive index 
of halowax and cottonseed oil mixtures was directly propor- 
tional to the per cent of oil present. The authors of Bulletin 
1471 observed the same relationship in halowax-linseed oil 
mixtures. The refractive index of halowax used in the investi- 
gation was 1.63354@25° C. and of the linseed oil, 1.47878 @29° 
C. The decrease in the refractive indice of halowax in mix- 
tures of the two was 0.001906 for each per cent of linseed oil 
present. 

Directions for Preparation of Conversion Tables—(1) Into 
three 4 ounce bottles, previously weighed, place approximately 
25 cubic centimeters of halowax oil and note the exact weight 


«Tal 


Examination of Flaxseed 571 


sa nEEnEEEEEEEEEEEEREE ae 


of the halowax oil added to each bottle. Next add linseed oil 
to each of the three bottles so that, by weight, a 10, a 12, and 
a 14 per cent solution of linseed oil in halowax oil will be ob- 
tained. Additional mixtures may be made if desired, but three 
will usually be enough. It is not necessary to obtain even per- 
centages of linseed oil in the mixture. As the optical method 
is standardized against the ether-extraction method, linseed 
oil obtained by ether extraction is used for making up the mix- 
tures with halowax oil. 

When the bottles containing the known percentages of lin- 
seed oil have been thoroughly mixed, read the refractive in- 
dex of each mixture, as well as the refractive index of the 
halowax oil used, at a temperature of 25° C., and from these 
data determine the change in the refractive index of the halo- 
wax oil per 1 per cent of linseed oil present in the mixture. 
The results will be of the order of 0.001906. The constant ob- 
tained will depend upon the original refractive indices of the 
halowax oil and the linseed oil used. 

(2) Determine the percentage by weight of linseed oil pres- 
ent in halowax oil when 4 cubic centimeters of halowax oil are 
mixed with a 2-gram sample of ground flaxseed. To do this 
the weight of 4 cubic centimeters of halowax oil must first be 
determined. This is accomplished by direct weighing of sev- 
eral 4 cubic centimeter portions of halowax oil or by determin- 
ing the specific gravity of the halowax oil and by multiplying 
this value by 4, the volume of halowax oil used in the test. 

Knowing the exact weight of the 4 cubic centimeters of halo- 
wax oil and the weight of linseed oil that would be present in 
flaxseed of known composition, the percentage of linseed oil 
in the halowax-linseed oil mixture when 2 grams of ground 
flaxseed are used in the test is now determined. To illustrate, 
suppose a sample of flaxseed contained 31 per cent of linseed 
oil. A 2-gram sample would contain 0.62 gram of oil. If this 
0.62 gram of oil was mixed with 4 cubic centimeters of halowax 
oil which weighed 4.904 grams, the percentage of linseed oil 
in halowax oil would be 11.224 per cent. Conversions of this 
nature are then made over any part of the scale from 3 to 49 
per cent as is illustrated in Table 69 in whole per cents and 
tenths of 1 per cent, depending on how extensive a table is 
desired. Ag an aid in‘ preparing this step in the conversion 
table the following formula will prove useful: 


Weight of oil in 2-gram sample of flaxseed Percentage 


Weight of 4 cubic centimeters of halowax oil—of linseed 


+ weight of oil in 2-gram sample of flax- oil in the 
seed mixture 


572 Examination of Flaxseed 


TABLE 69 
Percentages of iinseed oil in a halowax-linseed oil mixture made by adding 
4 cubie centimeters (4.904 grams) of halowax oil to 2 grams of ground flax- 
seed containing 31, 31.1, 31.3, 31.5, 31.7, and 32 per cent of linseed oil. 


Percentage 
Percentage of linseed oil 
of linseed oil in the halo- 
in flaxseed wax-linseed 
sample oil mixture 
31.0 11.224 
od 11.256 
31.3 11.320 
31.5 11.384 
ak Bg 11.448 
32.0 11.544 


(3) In the case of the experiments, the change in refractive 
index per each per cent of linseed oil present was 0.001906. 
All that is necessary, therefore, to express refractive index 
values in terms of the percentage of linseed oil present in 
ground flaxseed is to multiply each per cent and tenth of 1 per 
cent of linseed oil, as described in section 2 above, by the con- 
stant described under section 1. Finally, point off nine deci- 
mal places and subtract the value obtained from the refrac- 
tive index of the halowax oil used in the tests. The results 
will appear like those in Table 70, which is the section of the 
scale usually used for flaxseed. 

(4) As is general with optical measurements, the tempera- 
ture at which the readings are made is important. It is neces- 
sary when using this method to adjust individual readings to 
the same temperature basis. For general conditions 25° C. 
has been selected as an average laboratory temperature. Thus, 
for every degree above or below 25° C., 0.00045 is added to or 
subtracted from the original reading. This adjustment can 
not be overlooked, as this reading—0.00045—is equivalent to 
approximately 0.75 per cent of oil. 


_ Details of Method for Making Test.—(1) Grind 25 grams 
of the flaxseed sample so that at least 80 per cent of the meal 
will pass through a 34-grits gauze sieve. 

(2) Weigh out 2 grams of the ground sample and empty 
it into a 3-inch porcelain mortar, which has been previously 
heated to 70° C., and grind the flaxseed meal with 4 cubic 
centimeters of halowax coal grade No. 1007, for se least two 
minutes. 

(3) Filter through a small folded filter, using a 40- milli- 
meter glass funnel seated on a flat- bottomed test tube. 
(4) Let the tube and contents cool to room temperature. 


‘ 
‘s 
9 
; 

. 


. 


- 
i 
°S 
Rs 
% 
2 
sae 


» 
a 
Bi 


Examination of Flaxseed S75 


Place a drop of this mixture on the prism of the refractometer 
and take the average of three readings. 

(5) Note the temperature, and for every degree above 25° 
C. add 0.00045 to the refractometer reading and for every de- 
gree below 25° C. subtract this amount. 


TABLE 70 


For converting refractometer reading into percentages of linseed oil. 
(Readings made at 25° C.) 
Linseed oil 


Refractometer reading Per cent 
to lag ein ay ng kbd tans Ge cb ww sens ee ee e's 35.1 
ee Gee ics alc. Se <.disvs- dese bo ee ba Seine de hase ase poe 
ESS ASO a on ar a 35.3 
TOR RI laa lacs ook sss, visi cise sees ees tienecscensess 35.4 
Tete CNRS foe 6 core 5a 5 ods we wah 6 ass s’a sees vs eie sees 35.5 
TE te 7s 5 oe gd sls ads cy he seine s ket psececales 35.6 
Ee Pe Ss iole 3 Gino aise sss « « vise vcd-a sw ov seen ese aaens 35.7 
oat ae fe his ede ins’ o's odo ¥ % ace, 9 ¢ 0.08 disco ote ee eases 35.8 
Beeline ann cael als neo 3)s wee se-eiels"esale ad ee tye od wv b wie’ 35.9 
NM Ra gia sles Sov isig c's «sds lee cele pesbedeedees come’ 36.0 
Sah iw 5 Sa ss ce vos ole a doe Oa eh iy vale ae aloses 36.1 


(6) Wipe off the prism of the refractometer with a piece 
of soft absorbent cotton. 

(7) Note the percentage of oil in the sample under test by 
comparing the refractometer reading with a set of oil values 
which have been assigned to the refractometer readings. 7 

A study of 120 seed samples* by both the A. O. A. C. ether 
extraction and the optical methods shows that the results 
of 45.8 per cent of the samples tested by the optical method 
varied less than 0.1 per cent from the results secured by the 
method of the Association of Official Agricultural Chemists; 
39 per cent of the results varied 0.1 to 0.19 per cent; 14.2 per 
cent varied 0.2 to 0.29; and only 5 per cent varied 0.3 per cent 
or more, the greatest variation in any sample being only 0.33 
per cent. 

The method works equally well on linseed cake or meal. 
With the linseed cake it was necessary to pass the material 
through a burr mill in order to grind it to a fine state of sub- 
division. For sake of uniformity the linseed meal was also 
passed through a burr mill. 


SPECIAL Points FOR CONSIDERATION IN MAKING THE 


Optical TEst. 


Fineness of Division of Sample.—As the method was being 
developed it was brought out that the seed had to be pulver- 


*Details given in Bulletin 1471. 


574 Examination of Flaxseed 


ized to a very fine state of subdivision before accurate results 
were obtainable. It was found that seed ground on an attrition 
mill was not in a satisfactory condition as it was too coarse 
for rapid and complete solvent action. Many trials were made 
with grinding devices of various kinds, and it was finally de- 
termined that a small flouring mill, having rolls 6 by 6 inches, 
corrugated 40 to the inch, was the most satisfactory device for 
grinding flaxseed samples for analytical work. Such a mill 
reduces and pulverizes flaxseed without difficulty, to a point 
where over 80 per cent will pass through a 34 grits gauze in 
about four to five minutes. 


Volume of Halowax Oil to Use-——Experiments have shown 
that 4 cubic centimeters of halowax oil.is the optimum quan- 
tity to use with a 2-gram sample of flaxseed meal. With this 
quantity of solvent this method checks the ether-extraction 
method the closest. Although 3 cubic centimeters work well 
with some samples, with the majority this quantity is usually 
completely absorbed by the meal necessary for the test. 


Temperature at Which Readings Are Made.—The tempera- 
ture at which readings are made should always be the same in 
order that different operators may obtain concordant results. 
This end can be accomplished by using a conversion chart or 
by the continued use of a temperature regulator. It is be- 
lieved the chart system is preferable, inasmuch as less time is 
lost in making intial tests, because the operator does not have 
to wait until a specified temperature is reached. 


Temperature of Extraction.—The optimum temperature at 
which to allow the extraction to take place appears to be 70° 
C. Extracting in the cold reduces the percentage of oil ex- 
tracted. 


Filtering the Halowax-Linseed Oil Mixture —The filtering 
of the halowax-linseed oil Mixture is accomplished by the use of 
a small dry, folded filter, instead of the absorbent-cotton filter 
recommended by Wesson. By using the small folded filter, a 
cleaner filtrate is obtained and with less effort than when 
using absorbent-cotton filter. Only a few drops of the filtrate 
are necessary for making the refractometer reading. 


Cleaning Prism; Warning.—Because of the highly solvent 
action of the halowax oil, it is absolutely essential for accurate 
results that this material be completely removed from the 
faces of the prism after each test has been completed. Failure 
to do this will not only result in an incorrect oil test reading, 


but will also eventually result in a corrosive action on the back — 


of the prism. 


i Sic: 


CHAPTER XXXIII 


EXAMINATION OF WAXES AND POLISHES 


The principal use of waxes in the paint and varnish in- 
dustry is in polishes for use on automobiles and floors. The 
waxes which predominate are beeswax and carnauba. These 
waxes consist chiefly of esters of cerotic acid (C,;H;,COOH) 
or of homologous acids and myricyl (C;.H«,OH) alcohol. The 
fatty acids of the oils and fats are not present. Both bees- 
wax and carnauba wax contain some hydrocarbons, the former 
12.5 to 14.5 per cent and the latter less than 2 per cent. 


BrEswax * 


Refractive Index.—The refractive index of beeswax lies be- 
tween 1.4398 and 1.4451 at 75°, at which temperature pure 
beeswax is clear. For each degree above or below 75° C. 
0.00037 should be added or subtracted. 


Specific Gravity.—The specific gravity of beeswax may be 
determined by the following method. After eliminating all 
air bubbles by careful melting and then allowing to cool for 
2 to 24 hours, the sample is weighed in air and then in alcohol. 
The specific gravity is then calculated from the formula 
Weight in air 


a ee 
Loss in aleohol X sp. gr. of alcohol 


The specific gravity for pure beeswax lies between 0.961 and 
0.968 at 15.5°/15.5°. 


Melting Point.—The melting point of beeswax is determined 
by the capillary tube method, and averages about 60° C. 


Acid Number and Saponification Number.—Place 5 grams 
of the wax in a 200 ec. Erlenmeyer flask with about 25 ce. 
neutral aleohol and heat on the water bath until the mixture 
is entirely melted. Then add 1 ce. of phenolphthalein solu- 
tion and titrate the free acids quickly with N/2 alcoholic 
potash. Add 50 ec. more of the N/2 potash and heat the 
mixture for at least 3 hours over a direct flame with a 


*Much information presented in this chapter has been obtained from the 
following references: lL. Feldstein, U. S. Bur. of Chem. Cire. 86 (1911); F. 
Utz, Farben Ztg. 29, 645 (1924); Kebler & Boyles, U. 8S. Bur. of Chem. Bull. 
150 (1912) ; P. Bourcet, Bull. Soc. Chem. 39, 421 (1924). 


576 Examination of Waxes and Polishes 


reflux condenser. The excess of potash is determined with 
N/2 HCl. <A blank on the KOH should be run. The acid 
values range from 16.8-20.6, the saponification values from 
88-96. The ester value is the difference between the saponifi- 
cation value and the acid value. The ratio of the ester value 
to the acid value for pure beeswax ranges from 3.5 to 4. 


Detection of Stearic Acid.—Boil 1 gram of the wax for sev- 
eral minutes with 15 cc. of 80 per cent alcohol. Allow to cool 

to 18-20°. Filter into a 200 ec. cylinder and dilute filtrate with 
water to about 200 ce. If stearic acid is present, it separates 
into flakes and collects at the surface. The test is sensitive to 
1 per cent. If from 7 to 8 per cent are present, a thick, 
creamy mixture results. 


Detection of Resins —The following alternate methods may 
be used for determination of resins. 

(a) A mixture of 5 grams of the wax and 20 to 25 ce, 
HNO, (1.32 to 1.33), is kept at the boiling point for about 1 
minute. Dilute with an equal volume of water, and render 
slightly alkaline with NH,OH. The solution decanted from the 
separated wax, in the absence of resin, is of a yellowinsh 
color, while the presence of resin produces a more or less 
intense reddish brown coloration. 

(b) Heat 1 gram of the wax for a few minutes with 25 ce. 
or 50 per cent alcohol (this strength will not extract stearic 
acid if present). Cool and filter. Evaporate the filtrate to 
dryness on a steam bath, and add 5 ee. acetic anhydride. Heat 
to boiling. Cool and then carefully allow H.SO, (1.53) to 
flow into the solution. The presence of the minutest quantity 
of resin will develop a fine violet (fugitive) color. 

Detection of Paraffin—The following method is the only 
one by which paraffin can be detected with certainty. Melt 
from 2 to 5 grams of the wax in a porcelain dish, then add an 
equal weight of finely powdered KOH. Continue heating for 
a few minutes, with thorough stirring. Cool and powder the 
hard mass. Mix the resulting powder with three times as 
much potash lime as wax used. Then introduce this mixture 
into a thick walled tube, immerse in an oil bath; heat to 250° 
C. for 2 to 4 hours. After cooling, powder the tube with 
its contents. Place the mass in a Soxhlet apparatus and ex- 
tract with petroleum ether for several hours. The petroleum 
ether is evaporated, and the residue dried at 100° C. and 


Examination of Waxes and Polishes Sf 


weighed. By this treatment, the esters are converted into 
aleohols, and these alcohols on heating with potash lime are 
in turn converted into their respective acids, while the hydro- 
carbons present are not affected and are extracted with the 
petroleum ether. Pure beeswax contains from 12.5 to 14 per 
cent hydrocarbons, and any adulteration with paraffin or 
allied bodies will increase this percentage. 


Detection of Glycerin.—2 to 3 grams are heated in a large 
test tube on the water bath with 10 to 15 ce. KOH for 1 hour. 
15 ce. of water saturated with H.SO, are then added and the 
solution filtered. 2 cc. of this filtrate are then mixed with 20 
ec. of saturated bromine water, and heated 20 minutes on the 
water bath. The bromine is removed by boiling. 2 ce. are 
then put in a test tube with 0.1 cc. of a 1:20 solution of codeine 
in alcohol and 5 ce. of concentrated H.SO,, and heated 2 
minutes on the water bath. If glycerol is present, a beautiful 
bluish-green color appears, and this indicates the adition of 
an animal or vegetable glyceride. The method indicates as 
low as one per cent of glycerides. 


CaRNAUBA Wax 

Carnauba wax is used very widely in place of and in com- 
bination with beeswax in various preparations. The tests 
usually made to determine the purity of carnauba wax are 
Specific Gravity, which should be between 0.995 and 0.999 
and Melting Point, which should be between 83°-91°. The 
acid number, saponification number, etc. may also be run in 
the same manner as for beeswax. There is given below a 
chart showing the constituents of some of the more promi- 
nent types of waxes. 


TABLE 71 
Spec.Grav. Melting Acid Saponification Iodine Refractive 
15.5/15.5° Point °C. Value Value Value Index 
Beeswax ..... 0.961-0.968 60- 16.8-20.6 88-96 8.8-10.7 1.4398 
-1.4451 
Ce TH 2G, 
Candelilla .... 0.969-0.993 65-68 VG: 46-65 14.0-36.8 1.454 
Carnauba .... 0.995-0.999 65-69 4-8 79-84 138.5 Ate 
de 76-92 73 74 16. 
Spermaceti ... 0.905-0.960 41-46 0.5-2.8 126-135 22:6 


FinisHED Wax Propvucts 


The tests that should be made on wax products such as 
automobile polishes, shoe polishes, etc., to determine the con- 


578 Examination of Waxes and Polishes 


stituents should include volatile matter. This determination 
is carried out in the following manner. A small stoppered 
weighing bottle containing 2-3 grams of the material is 
weighed. 1-1.5 grams of the contents are quickly transferred 
to a previously weighed 3-inch friction top can plug and the 
bottle again weighed. The difference is the weight of the 
polish. The lid and its contents are then heated for 3 hours 
at 115°-120° C. cooled and weighed, the percentage non-volatile 
is calculated from the residue in the dish and the weight of 
material taken. The character of the volatile solvent em- 
ployed should be determined. These solvents are usually 
turpentine, mineral spirits or similar materials. The non- 
volatile wax portion may be used for a determination of melt- 
ing point or for other tests such as those outlined above. The 
product should also be subjected to a practical test upon the 
kind of surface on which it is to be employed in order to 
determine its suitability in this direction. 


Sa a 


CHAPTER XXXIV 


TESTING RAW MATERIALS USED IN LACQUER 
MANUFACTURE 


The tests usually applied to nitrocellulose are Viscosity, 
Color, and Stability. These are outlined below. There are 
also included some tentative methods of examining solvents, 
diluents, and pigments proposed for lacquer use. 


Viscosity of Nitro-Cellulose.*—The viscosity of a nitro-cellu- 
lose solution is measured in many different ways and there 
are several standard units of measurement, such as seconds, 
poises, bubbles, torque, ete. The method used by nitrocellu- 


INSIDE OIA. 


10.% DIA, BALL BEARING 
(OIA. 0.793 T0.0.797CM 
WEIGHT OF BALL 2.046h|4 


TEMP OF SOLUTION 457i 


THE APPARATUS FOR DETERMINING VISCOSITY 

OF A SOLUTION BY THE FALLING BALL METHOD 

CONSISTS OF A GLASS TUBE 14 INCHES LONG 

HELD IN A VERTICAL POSITION BY A STAND AND 

CLAMP. ON THE GLASS’ TUBE ARE TWO MARKS 

2 INCHES FROM THE TOP AND BOTTOM AND 
EXACTLY 10 INCHES APART 


FIGURE 196 


lose manufacturers and the one most commonly used in the 
lacquer industry for the examination of nitrocellulose is the 
falling ball method. This consists in measuring with a stop 
watch the time required for a steel ball to fall through ten 
inches of a solution in a one-inch-diameter vertical column 


* Weisel method. 


580 Raw Materials Used in Lacquer 


at a temperature of 25 degrees C. It is quite important that 
the temperature be kept constant, as any variation in tempera- 
ture will vary the viscosity, as will be noted by reference to 
the curve showing the relation between viscosity and tempera- 
ture. As 25 degrees C. is approximately room temperature 
(77° F.) it is not difficult to prevent temperature change. For 
determination of the viscosity of all types of nitrocellulose 
except half-second types, the Hercules Powder Company has 
adopted the following method: 


Apparatus.—A 14-inch glass cylinder of one-inch inside 
diameter having two marks 10 inches apart. One mark should 
be two inches from the top of the cylinder and the other two 
inches from its bottom. A standard 5/16 inch steel ball bear- 
ing with diameter of 0.793 to 0.797 cm. and weighing between 
2.046 and 2.054 grams. A Centigrade thermometer. <A cork 
enclosed in tinfoil and a stop-watch. 


Method.—The nitrocellulose is put into solution of the fol- 
lowing formula: 


Lbs. per __ Lbs. per 
100 Lbs. Gallon 


Nitrocellulose (Dry Weight)......... 12.2 0.94 
Denatured Alcohol . .... 3.2 220) 1.69 
Ethyl. Acetate 2.2 ..0.. ee Li 1.35 
Benzol iv ee Pe ea eee 48.3 ould 

100.0 7.69 


After the Nitrocellulose is thoroughly dissolved, the solu- 
tion should stand about one hour to permit bubbles to escape. 
The sample is then brought to a temperature of 25° C. and the 
glass cylinder is filled. The ball bearing igs then placed on 
the surface of the sample in the cylinder and allowed to fall 
through the solution. The cylinder should be held or sup- 


ported in an exactly vertical position and the ball should be 2 


dropped exactly in the center. The time required for the ball 
to fall through the ten-inch column of solution is recorded in 
seconds and reported as the viscosity of the Nitrocellulose. 


Control Test for Half Second Types.—tIn the following 
test, made for the purpose of determining the viscosity of half- 
second types of nitrocellulose, a different formula is used for 
the nitrocellulose solution. It is necessary to make a measure- 
ment in a solution of higher viscosity and reduce the result 


Raw Materials Used in Lacquer 581 


to terms of viscosity equivalent to the standard solution. 
With very low viscosities the time interval is so small that 
the determination is more or less of a guess, depending upon 
the skill and personal equation of the operator. The appa- 
ratus and method is the same as for other types except that 
the nitrocellulose is put into a solution of the following for- 
mula. 


Half Second eect nee (dry weight)..... 20 % 
I SS a ee ns 20 % 
NE 2 ee 16% 
er ee ke ee eka eee 44% 

100 % 


Although there are many factors which govern the viscosity 
of a solution, such as temperature and solvent used, the prin- 
cipal factor is the nitrocellulose itself. The viscosity of a 
nitrocellulose is controlled by many conditions. The quality 
of the linters resulting from the type of cotton, its maturity, 
purification and degree of bleaching affect viscosity. 

Different solvents give solutions of different viscosities 
with the same nitrocellulose. In general the better the sol-. 
vent the lower will be the viscosity. For example, acetone 
will give a lower viscosity solution than ethyl or butyl acetate 
for some types of nitrocellulose. Decreasing the proportion 
of solvent to diluent usually increases the viscosity. Adding 
diluent to a solution will increase the viscosity until the nitro- 
cellulose is finally thrown out of the solution. The use of py- 
ridine denatured alcohol in the manufacture of lacquers should 
be avoided because the pyridine content is detrimental to the 
solution on account of its drastic action in reducing the vis- 
cosity. This viscosity reduction is caused by the rapid de 
composition of the nitrocellulose. As there is no known 
method of stopping this action, such will continue until the 
nitrocellulose is disintegrated. 

An increase in the concentration of a solution does not 
necessarily give a proportionate increase in viscosity (as de- 
termined by the falling ball method). As nitrocellulose is 
added to a solution there is at first a very slight increase in 
viscosity. As more nitrocellulose is added to the solution the 
viscosity increases more rapidly in proportion to the nitro- 
cellulose added. 


582 Raw Materials Used in Lacquer 


Changes in temperature* very readily affect the viscosity 
of a solution. The higher the temperature, the lower the vis- 
cosity ; hence the necessity, when testing for viscosity, of keep- 
ing the solution at a fixed temperature, which is standardized 
at 25° C., as this is about normal room temperature, and most 
convenient to maintain. 

The following table shows how vara in temperature 
affect viscosities. 


VISCOSITIES OF 4, 20, 70, AND 140 SECOND NITRO-CELLULOSE 
SOLUTIONS BETWEEN TEMPERATURE RANGE OF 10° C TO 40° C 


VISCOSITIES 

as 4 sec. 20 Sec. 70 Sec. 140 Sec. 
40° C. 1.96 9.78 34.25 68.49 
9 hea ON 2.48 12.42 43.46 86.92 
30° C, 3.15 15.76 55.16 110.3 
Zoe ha: 4.00 20.00 70.00 140.0 
20° C, 5,08 25.38 ~~ 88.84 L773 
153 0. 6.44 S221 112.8 odo 
10° GC. 8.18 40.88 143.1 286.2 


Stability and Durability of Nitro-Cellulose.—The stability 
of nitrocellulose, or the property of resisting deterioration or 
decomposition, is of great importance to users of nitrocellu- 
lose. Stability in a nitrocellulose product is a property that 
receives very careful consideration from many of the indus- 
tries using nitrocellulose. Any treatment of the nitrocellulose 
by users which would tend to decrease its stability should be 


——_ 


strenuously avoided and the greatest care taken to secure from _ 


manufacturers a properly stabilized nitrocellulose. The use 
of pyridine denatured alcohol in the manufacture of lacquers 
should be avoided because the pyridine content appreciably 
affects the stability of the nitrocellulose. 

One of the most reliable tests for determining the stability 
of nitrocellulose is the 

German or 135° C. Stability. Test—The method used to de- 
termine whether nitrocellulose has the required degree of sta- 
bility is that known as the German Stability Test, which is 
sometimes referred to as the 135° C. Stability Test. The 
necessary data to make this test are given below: 

* See also “‘Some Observations on the Viscosity of Lacquers,” by C. D. Bogin 


and C. W. Sims to appear in Jour. Ind. and Chem. End. early in 1928. 
y Also % second nitrocellulose in a 20% solution. 


ee ee ae 


Raw Materials Used in Lacquer 583 


The bath used is of special design, built so that any desired 
temperature can be maintained by means of a constant boiling 
mixture. This bath can be obtained from Kimer & Amend, 
New York City, who have the necessary data for making it 
and who make them on order. An ordinary laboratory elec- 
tric hot plate is used to heat the bath. 


The glass tubes used in making the tests are 290 mm. long, 
15 mm. inside diameter, and 17 mm. outside diameter. These 
tubes are made from standard pyrex tubing having an exter- 
nal diameter of 17-18 mm. and regular walls. The small vari- 
ations in the regular stock tubing of the above specifications 


K 15-STD Z COPPER TUBES SPACED 
EENDS FINISHED AS SHOWN 
ae ) 103 LONG 

2x3 133 Brass PAD 

or tad UNDER $!DE OF 


S1D 3 BRASS UMOK 


Ss 
DRILL& TAP FOR peineoee eda 


S10} coprer Pipe 
: 3 STO FCOPPERPIP 
: STOZ PIPE PLUG BRASS 


” ple-coppen SHEET THRUOUT +| i lh 
—E—E— % 


2 of 
-|\so 


CONSTRUCTION OF BATH FOR GERMAN (OR 135° C) 
STABILITY TEST OF NITROCELLULOSE 


FIGURE 197 


do not affect the results. The tubes as made will project 6 
or 7 mm. out of the bath, permitting ease in handling. The 
solvent mixture used in the bath to maintain a temperature of 
135° C. is approximately one part Xylol and four parts Toluol. 
The exact mixture is found by ‘‘eut and try.’’ If the mixture 
started with is too high more Toluol is added. If it is too 


584 Raw Materials Used in Lacquer 


low, the condenser is allowed to run hot until the proper 
temperature is reached. Because of the inflammable nature 
of the solvents, care should be used not to allow any great 
quantity to escape into the room without proper ventilation 
and precautions. On continued operation the tendency is for 
the temperature to rise, which is corrected by adding Toluol. 
The temperature is read from a thermometer placed in a stop- 
pered empty glass tube so that the bulb of the thermometer 


OPEN ENO 


‘ 
ok 


BRAZE 


STD. 2"BRASS PIPE CAP 


STD. 2" BRASS PIPE— 


WATER OUTLET SAME 
AS WATER INLET 


WATER INLET 
by ‘ 
STD, 4 BRASS PIPE a 


ws STDZ BRASS UNION 


Lee 


ER OFF WITH FIL 
og Pee 
' 


| 


TAP 


STO. 2 BRASS PIPE— 


| whe 


STO. PIPE THO. FOR 2 BRASS 
“UNION 


CONDENSER FOR GERMAN HEAT TEST BATHE 
FIGURE 198 


occupies the same position as a sample of nitrocellulose. The 

thermometer should read to tenths of a degree centigrade. 
The methyl violet paper used is specially made so that the 

eolor reactions are extremely sensitive to nitrous oxides. 


Raw Materials Used in Lacquer 585 


They should be stored in a well stoppered bottle away from 
any acid fumes. [Every new lot of papers received should be 
checked against a standard to see whether they give the same 
results as the previous lot received. 


It is absolutely compulsory that a mask be worn protecting 
the eyes and face whenever making this test. The mask should 
be so made that a heavy sheet of clear cellulose acetate cellu- 
loid is held in front of the face, thus protecting the eyes and 
face from flying glass in case any unstable sample should flare 
while being tested. While handling the tubes the hands should 
be protected. This can easily be done by wearing heavy 
eloves and using long pincers so that the hands are not over 
the bath. The test is conducted in a room free from any acid 
fumes whatsoever, preferably in a room by itself, but if this 
is impossible then in some location where there will be no 
damage from flying glass if a sample should flare. 


The nitrocellulose is dried thoroughly, which is best accom- 
plished by drying in an oven at 50° C. for fifteen hours. The 
sample should be thoroughly dried, as the presence of alcohol 
influences the test as well as lowers the weight of nitrocellu- 
lose being tested. The weight of sample used is 2.5 grams, 
which is shaken or pressed down in the tube so that it occupies 
the lower two inches in the tube, making sure that no nitro- 
cellulose adheres to the upper part of the tube. The methyl 
violet papers are then suspended in the tube by hanging them 
on a hook made on the end of a glass rod run through a cork 
fitted in the top of the tube. This cork should be notched 
along the side in order to take care of the expansion and con- 
traction of air in the tube. The paper is so suspended that 
its lower edge is one inch from the top of the nitrocellulose. 
The bath is maintained at a temperature of 134.5° C+0.5° C. 
After heating the sample for 10 minutes, the tube is inspected 
at five-minute intervals. The determination is the time, in 
multiples of five minutes, required for the methyl violet paper 
to completely lose its violet color. An inspection of the methyl 
violet paper is made by lifting the tube until the paper, but not 
the nitrocellulose, is visible above the surface of the bath. 
Properly purified nitrocellulose should stand a test of 20 min- 
utes or more by this method. 


In conducting this test it is extremely important to take 
into consideration that dried nitrocellulose is very inflamma- 


586 Raw Materials Used in Lacquer 


ble and that if it is ignited by fire, spark or static electricity 
that the whole mass will flare very quickly. It is compulsory 
that a mask be worn whenever making the test because if a 
sample should flare during the test the glass tube will be shat- 
tered and thrown to all parts of the room. Unless the face 
is protected with a proper mask, the flying glass may seriously 
injure the eyes and cut the face. 

All stability tests are purely comparative and are used on 
the basis that if a certain result is obtained, the material will 
have certain properties based on past experience. If you 
get twice the reading on one sample that you do on another, 
it cannot be said that the higher one will last twice as long as 
the other when exposed to destructive agencies unless past 
comparisons have been made showing this. However, the 
test is valuable in quickly saying whether the material is of 
the required degree of stability. 

Methyl Violet Papers.—The methyl violet papers used in 
making the German Test for stability are made according to 
the following procedure: 

The dye solution used is made from the following formula: 

Basic Rosaniline (converted to acetate) 0.2500 grams 


Crystal Violet’ 2.0.4... . 55 0.1680 grams 
C.. P. Glycerine. (2 =. 6 ce. 
Distilled Water 2.2). Gt bil er 30 ee. 


Knough of 95% ethyl aleohol is added to the above solution 
to give 100 ce. of solution. 


The rosaniline acetate used in the above is made by placing 
0.2500 gram of basic rosaniline in a porcelain casserole, add- 
ing an excess of glacial acetic acid and the casserole heated 
on a steam bath until all the excess acid is removed. The 
other ingredients are then added and the whole made up to 
100 ce., using 95% ethyl aleohol. A small quantity of the solu- 
tion is then placed in the deep angle of an inclined rectangu- 
lar glass tray. A quarter sheet of S and S No. 597 filter paper 
is then drawn through the solution and up over the side of 
the dish to remove the surplus solution. The filter paper 
used is an important factor in the results obtamed and it is 
quite essential that the proposed paper be used. This opera- 
tion should take 30 seconds. The strip should then be held 
horizontally and gently waved to and fro so as to preclude 
the possibility of the solution running or collecting in spots. 


Raw Materials Used in Lacquer 587 


The alcohol dries rapidly, so that within a minute the strip 
may safely be suspended vertically without danger of the 
solution running. When air-dried the paper is ready to be 
cut into strips 70 mm. long and 20 mm. wide. A hundred ce. 
of the solution makes about 250 of the strips. These papers 
should be made in a room free from any acid vapors whatso- 
ever, especially nitric acid. It is claimed that this paper is 
not affected by air, light, change of temperature, carbonic, 
acetic, hydrochloric or sulphuric acids. Making these papers 
is a very delicate operation and it is very necessary that every 
fresh batch be checked against the papers held as a standard 
by making tests, using both papers on the same sample of 
nitrocellulose. 


A. S. T. M. RECOMMENDED TENTATIVE SPECIFICATION 
FOR SOLUBLE NITROCELLULOSE* 


1. These specifications cover the material known as soluble nitrocellulose, 
also known as soluble cotton, which is shipped wet to conform to the regula- 
tions of the Interstate Commerce Commission. 


I. PROPERTIES. 
2. The material shall conform to the following requirements: 

(a) Appearance—It shall not be discolored and shall be free of lumps 
and foreign matter, such as charred particles. 

(b) Ash—The maximum ash content allowable is 0.30 per cent, 
ealeculated on the basis of dry weight soluble nitrocellulose. 

(c) Nitrogen—The per cent nitrogen, calculated on the basis of dry 
weight soluble nitrocellulose, shall be within the limits agreed 
upon by the buyer and seller for the particular type of soluble 
nitrocellulose. 

(d) Stability—The methyl violet test paper shall not be completely 
changed to a salmon pink color in less than 20 minutes. 

(e) Viscosity—Material shall be within the limits agreed upon by 
buyer and seller for the particular type of soluble nitrocellulose. 

(f) Solubility and Appearance of the Solution—The sample shall be 
equal to the standard for the particular type of soluble nitrocellu- 
lose. 

(g) Film Test—The sample shall be equal to the standard for the 
particular type of soluble nitrocellulose. 

(h) Toluol Dilution Test—The dilution value of the sample shall be 
as great as that of the standard for the particular type of soluble 
nitrocellulose. 


* Prepared by Sub-Com. 25 of Com. D. I.—A. S. T. M. for consideration 
of committee. 


588 Raw Materials Used in Lacquer 


II. SAMPLING. 

3. Samples shall be taken from 2 barrels of each lot or batch in the ship- 
ment. The composite sample representing a single barrel shall be obtained 
by taking 2 samples of approximately 1 pint each from 2 well separated points 
at least 1 foot beneath the surface of the material in the barrel. Each barrel 
sampled shall be tested and reported separately. 


Ill. METHODS OF TESTING. 

4. The determination of ash shall be made as follows: 

One gram dry soluble nitrocellulose is weighed out in a previously dried 
and weighed platinum crucible which is then heated to 95°-100° C. to constant 
weight (about 30 minutes being required). After cooling the nitrocellulose is 
then moistened with 10-15 drops of C. P. nitric acid and heat the crucible on 
a steam bath until the sample is decomposed to a gummy mass. It may be 
necessary to add several additional drops of nitric acid at intervals to com- 
plete the decomposition. Then heat the crucible slowly over a Bunsen flame 
or in an electric furnace until all volatile matter is driven off. Finally, ignite 
at red heat to constant weight. Cool in a dessicator and weigh. 

5. The determination of nitrogen shall be made as follows: 

The nitrogen determination of soluble nitrocellulose is most readily made 
by means of the nitrometer. A complete description of the apparatus and 
its manipulation is given in the United States Bureau of Mines Technical 
Paper No. 160 on “The Determination of Nitrogen in Substances Used in 
Explosives,’ which can be obtained through the Superintendent of Documents, 
Government Printing Office, Washington, D. C. Complete description is also 
given in Worden’s book on “Technology of Cellulose Esters,” page 972. 

The reading and measuring burettes should be accurately calibrated, which 
is done in the usual manner, using mercury as the calibrating liquid. 

The apparatus must be accurately standardized, and of the two methods 
given in the above publications the one using absolutely pure potassium 
nitrate is far preferable. . 

The nitrocellulose should be roughly dried at 50° C., then 1.0 to 1.05 grams 
are roughly weighed in a tared weighing bottle and dried to constant weight 
at from 90-100° C. cooling in a dessicator and accurately weighed. The 
sample is then transferred to the cup of the generating bulb of the nitrometer ; 
then exactly 25 ec. of the 95% +1% (sp. gr. 1.84) C. P. sulphurie acid used 
in the standardization of the nitrometer is used to dissolve the nitrocellulose 
and wash the final traces of nitrocellulose in the weighing bottle and cup of 
the generating bulb into the generating bulb. The bottom stopeock of the 
generating bulb must be left open at all times during this operation. Then 
with the bottom stopcock open and a vacuum on the generating bulb the 
decomposition is started by gently shaking the bulb. After the rate of decom- 
position has slowed down, the leveling bulb is lowered enough to draw all 
but 25 ce. of the mercury out of the generating bulb, the bottom stopcock is 
closed and the whole vigorously shaken for five minutes to insure complete 
decomposition of the nitrocellulose. The gas is then allowed to cool and is 
then transferred to the reading burette and measured. The result is expressed 
as per cent of nitrogen in the dried samples soluble nitrocellulose. 

It is very important that the bottom stopcock be left open until the major 
part of the decomposition has taken place, otherwise the sudden, evolution of 


Raw Materials Used in Lacquer 589 


gas will rupture the bulb, throwing acid and glass into operator’s eyes and face, 
causing blindness and deep life scars. Also a cellulose acetate mask should 
be worn as a safeguard during the entire time of making the test. 

6. The method for stability given in this specification is the method 
shown on page 582 and is not reprinted here because of lack of space. 
Pr A. G.). 

7. The “viscosity” of soluble nitrocellulose shall be determined by putting 
it in solution using a standard formula and noting the rate at which a 
standard steel ball drops through the solution. 

The 2 solution formulas used are given below: 

% by Weight 


SoA ‘“p”? 
Soluble Nitrocellulose (dried at 50° C. to constant weight)... 12.2 20.0 
NE ES oi race we cn os beds cece wep eects weeaceas 17.5 16.0 
Seeeoemreue rn conol, ©. 1. No. 1 188 '‘Proof..............608% Zoy 20.0 
POD vies viene ce cise eee 1 BORE Ska ry ORE ot eae i Oia A 48.5 44.0 


Formula “A” shall be used unless the soluble nitrocellulose under examina- 
tion gives a “viscosity” with it of 6 seconds or less, in which case Formula 
“B” shall be used. After the soluble nitrocellulose is completely dissolved, 
fill a glass cylinder having an inside diameter of 1 inch, a height of 14 inches, 
arid marks on the side 2 inches and 12 inches from the top. Bring the cylinder 
and contents to 25° C. and allow to stand until all air buihles have passed 
out of the solution. Then release a standard 5/16 inch ball bearing weighing 
2.046-2.054 g. (diameter 0.793 cm.-0.797 cm.) at the surface of the solution 
and allow it to fall through the solution. The number of seconds required 
for the ball to pass through the 10-inch column of solution between the marks 
on the cylinder is taken as the “viscosity” of the sample. To this number the 
letter “A” or “B” is prefixed to indicate the formula used, e. g., “A 8.” 

8. The test for solubility and appearance of the solution shall be made 
as follows: 


Compare the sample in Formula “A” or Formula “B” with a standard 
solution of the same type of soluble nitrocellulose in the same formula. The 
comparison is made in small vials, noting color, turbidity, “grain” and “flock.” 
When soluble nitrocellulose is to be used for purposes requiring extreme 
transparency and clarity the sample and standard are compared in the same 
manner, using Formula “C.” 


EORMULA “CGC” 
% by Weight 
Soluble Nitrocellulose (dried at 50° C. to constant weight)........ gees 
Seuty) Acetate....... ETA ee ets ee ee ie ee ee ee 87.8 


9. The film test shall be made as foliows: 

Thin Formula “A” or Formula “B” with an equal volume of butyl acetate 
and pour the solution beside the standard on a clean giass plate. Allow the 
film to dry in a dust free atmosphere and compare sample with standard for 


* Ethyl Acetate 85%—balance unconverted alcohol. 


7+ Toloul 2° boiling range including boiling point of toluene 110.7° G.— 
non-corrosive. 


+ Butyl Acetate 85-90% ester 


balance unconverted alcohol. 


590 Raw Materials Used in Lacquer 


a eareer re eneeeeneeee nnn ERNIE EEnenammmnnaemmmamaaatal 


undissolved particles, which indicate un-nitrated cotton or impurities, and for 
poor flow and poor gloss. 

10. The toluol dilution test shall be made as follows: 

Dissolve the sample according to Formula “C.” To 50 ce. c. of this solution 
add ce. p. toluol in small quantities from a burette, stirring well after each 
addition. The first permanent separation of soluble nitrocellulose is taken 
as the dilution value and is expressed as a per cent by volume of Formula 
“a.” Large quantities of butyl acetate and toluol should be reserved for these 
tests to avoid possible variation between different lots. 


TOLERANCE TO DILUENTS 


Nitrocellulose—Two grams of nitrocellulose are dissolved 
in 20 ec. commercial butyl acetate and titrated with the de- 
sired diluent until the nitrocellulose is precipitated or the end 
point is seen in another manner, as described below. The 
results are reported as the number of ec. of diluent per cc. of 
solvent (butyl acetate). 


Lacquer Base.—It may be advantageous to know the exact 
amount of dilution which a lacquer base, probably consisting 
of nitrocellulose, solvent, gum, and plasticizer, will stand. 
This laboratory uses the following method: Fifty grams of 
the lacquer base is weighed out into an Erlenmeyer flask and 
titrated with the diluent to be used. The results are reported 
.as ec. of diluent per gram of lacquer base. 


End Points.—The end points in the foregoing determina- 
tions are rather indefinite, and experience is necessary to be 
able to check the results. Some diluents throw out the cotton, 
which can be readily seen. A second class of diluents seems 
to gradually increase the viscosity of the solution until the 
entire mass becomes a gel. A third class of diluents is mis- 
cible with the solution up to the end point where a definite 
separation of further diluent occurs. 


Testing the Bulking Values of Nitrocellulose.—Dissolving 
one pound of dehydrated nitrocellulose* in any volume of 
the following solvent mixture increases the volume 0.0938 
gallons—as, for example: 

1 lb. Dehydrated Nitrocellulose containing: 0.7 lb. dry ni- 
trocellulose, 0.3 lb. denatured alcohol dissolved in 1 gal. Sol- 
vent Mixture consisting of: 0.5 gal. Toluol, 0.5 gal. Butyl 
Acetate yields in pyroxylin solution 1.0938 gallons. This is 
known as the bulking value. 


* 70% nitrocellulose and 30% alcohol. 


ere 


Nixes 


oer 
a’ 


LR eae AS 


picemeien® 


; 
5 a 


my 


J 


- 


ire al 
* 


Wee Om er a 
5 ve 
ied Pe 7 hill ‘Aico 


Raw Materials Used in Lacquer 591 


In the above mentioned mixture there is no difference in 
bulking value for Nitrocellulose of different viscosities and 
concentrations. These results are in terms of absolute den- 
sity at 25° C.* 


Examination of Lacquer Pigments.—Sub-Committee XXV 
of the A. S. T. M. has been doing some work with the object 
in view of describing tests for pigments which are to be used 
in lacquer. Some of the preliminary suggestions made for 
the testing of such pigments are given below. 


SAMPLING 


Barrels.—At least 10 per cent of the barrels or kegs in any 
shipment of white or black pigment shall be sampled and each 
package shall be tested separately. 


Bags.—When white or black pigments are received in bags, 
at least 1 per cent of the packages shall be sampled and each 
package shall be tested separately. For all other pigments, 
each package shall be sampled and tested separately. 


LABORATORY EXAMINATION 


Bleeding.—This test shall be run only on pigments that 
are liable to cause bleeding. Mix suitable amounts of the 
sample under test and the standard with a clear lacquer and 
spread evenly on a portion of a smooth metal panel. Allow 
to dry one-half hour, then flow successive coats of white 
lacquer over the covered portion of the panel and an adjoin- 
ing area, until complete hiding is obtained. Note whether the 
colored layer bleeds into the white, which would be indicated 
by a difference in the color of the two sections of the panel. 


Alternate Method for Bleeding.—Place 0.5 g. of the pigment 
in a test tube with 25 cc. of the lacquer solvent. Shake, allow 
to settle and then filter. If filtrate is colored, determine with 


microscope whether it is due to particles in solution or in sus- 
pension. 


Acidity or Alkalinity.—This test shall be run only on plg- 
ments that are likely to be excessively acid or alkaline. Shake 
10 g. of the sample with 100 ce. of 99 per cent methyl alcohol 
for 30 minutes, using a mechanical shaker. Filter and titrate 
with N/50 KOH or H2SQ,, using phenolphtalein as indicator. 


*One pound dry nitrocellulose (no alcohol or water bulks 0.0706 gallons). 


S92) Os Raw Materials Used in Lacquer 


ES 


Express results as mgs. KOH required to neutralize 1 g. of 
sample, or as mgs. KOH in 1 g. of sample. 


Moisture and Other: Volatile Matter—The moisture shall 
be determined as follows: 

Method ‘‘A’’—for colors that do not decompose at 110 de- 
grees C. Place 5 to 10 g. of sample in a weighed aluminum 
moisture dish with a tightly fitting cover and weigh. Par- 
tially remove cover and heat at 105 to 110 degrees C. for two 
hours. Replace cover, cool in a dessicator and weigh. Repeat 
heating for periods of half an hour until constant weight is 
reached. Report the total loss as moisture and other vola- 
tile matter. In this determination the cover of the moisture 
dish should be removed only to receive the sample and when 
heating in the oven. 

Method ‘‘B’’—for colors that decompose at 110 degrees C. 
Method to be developed. The methods proposed for consid- 
eration are drying in a vacuum oven and the Standard Meth- 
od of Test for Water in Petroleum Products and Other Bitu- 
minous Materials, A. 8. T. M. Standards, D 95—24, with the 
following variations and additions: 

The sample shall be 25 g. The solvent shall be 79 ce. of 
xylol, previously saturated with water by shaking with an 
excess of water in a separatory funnel, drawing off and dis- 
tilling. The distillation shall be continued until the distillate 
comes over clear and the condenser then washed down with a 
cotton swab saturated with xylol.. From the volume of water, 
caleulate the percentage by weight. 


Testing Lacquer Solvents.—The tentative methods of tests 
adopted at the June, 1927, meeting of the A. 8. T. M. are pre- 
sented below: 


A.S.TL.M. TENTATIVE METHODS OF SAMPLING 
AND TESTING 


LACQUER SOLVENTS’ AND DILUENTS 
1. These methods cover the sampling and tests to be applied to solvents and 


diluents for use in the manufacture of nitro-cellulose lacquer. 


SAMPLING 
2. (a) The method of sampling specified in Paragraph (b) or (ec) shall 
be used, according to the special conditions that obtain. 


(b) From Loaded Tank Car or Other Large Vessel.—The composite sample — 


taken shall not be less than 4 gal. and should consist of small samples of not 
more than 1 qt. each, taken from near the top and bottom by means of a metal 
or glass container with removable stopper or top. This device, attached to a 


suitable pole, shall be lowered to the desired depth, when the stopper or top — 


shall be removed and the container allowed to fill. 


powr- ey gp ee Sa es wae aT 


Oe eee ere nee 


Raw Materials Used in Lacquer 593 


(c) Barrels and Drums.—At least 5 per cent of the packages in any ship- 
ment shall be represented in the sample. The purchaser may increase the 
percentage of packages to be sampled at his discretion, and it is recommended 
that every package be sampled in the case of expensive solvents that are 
bought in small quantity. A portion shall be withdrawn from about the center 
of each package sampled by means of a “thief” or other sampling device. The 
composite sample thus obtained shall not be less than 1 qt. and shall’ consist 
of equal portions of not less than 1% pt. from each package sampled. 


METHODS OF TESTING 

3. Specific gravity shall be determined for all solvents and diluents. The 
determination shall be made at 20° C. by any convenient method that is 
accurate to the third decimal point. 

4, Color shall be determined for all solvents and diluents. The sample 
and the standard mutually agreed upon by the buyer and seller shall be 
compared in 50-cc. Nessler tubes against a white background. For a solvent 
to be rated water-white, the visible color shall not be darker than a solution 
of 0.0030 g. of potassium bichromate in one liter of water. 

5. The distillation test shall be conducted on all solvents and diluents, 
in accordance with the Tentative Method of Test for Distillation of Gasoline, 
Naphtha, Kerosine, and Similar Petroleum Products (Serial Designation: D 
86-26 T) of the American Society for Testing Materials,* except that the 
observations made shall be not of volumes of distillate coming over at certain 
specified temperatures, but of the temperatures at which certain specified 
volumes of the distillate come over. The temperature shall be observed and 
recorded at first drop of the distillate, and when the volume of the distillate 
collected, observed to the nearest 0.5 ce., reaches 5 ce, 10 cc, 20 cc, 30 
ec., 40 ec., 50 ce., 60 ce., 70 ec., 80 cc, 90 cc., 95 cc., and end point. 

6. The residue shall be determined for all solvents and diluents. Using 
a pipette, 5 ec. of the sample and of the standard shall be placed in separate 
porcelain evaporating dishes. These samples shall be allowed to evaporate 
in a hood for 24 hours. If any residue remains, its nature shall be noted and 
the test for non-volatile matter shall be made as described in Section 7. 

7. Non-volatile matter of solvents and diluents shall be determined only 
when its presence is indicated by the results obtained in Section 6. One 
hundred cubic centimeters of the sample shall be placed in a weighed porcelain 
evaporating dish and evaporated almost to dryness on a steam bath. It shall 
then be heated in an oven at 100 to 110° C. to constant weight. The increase 
in the weight of the dish is the non-volatile matter of the sample, which should 
be expressed as a percentage, calculating the weight of the sample from its 
specific gravity, determined as described in Section 3. 

8. Residual odor shall be determined for all solvents and diluents in which 
residual odor is an important property. Strips of heavy filter paper, of the 
same size and shape, shall be dipped to the same depth in beakers or wide- 
mouthed bottles containing the sample and the standard. They shall then be 
attached to a piece of wood. with thumb tacks and at suitable intervals exam- 
ined for difference in odor. 


* Proceedings, Am. Soc. Testing Mats., Vol. 26, Part I, p. 816 (1926) ; also 
1926 Book of A.S.T.M. Tentative Standards, p. 388. 


594 Raw Materials Used in Lacquer 


9. Water shall be determined for all solvents and diluents. Five cubic 
centimeters of the sample shall be transferred to a 100-cc. glass-stoppered 
cylinder, and 60° Baumé gasoline added in 5-ec. portions, shaking well after 
each addition. Water is indicated by turbidity. If turbidity develops, the 
standard shall be tested in the same way and compared. 

10. Acidity shall be determined for all solvents and diluents. Using a 
pipette, 50 cc. of the sample shall be transferred to a small Erlenmeyer flask 


and titrated with 0.1 N KOH in 99-per-cent methyl alcohol, using phenoph- — 


thalein as an indicator. The weight of the sample shall be determined 
from the specific gravity and the acidity reported as milligrams of KOH per 
gram of sample. 

11. Alkalinity of solvents and diluents shall be determined only when 
indicated by the results obtained in Section 10. Using a pipette, 50 cc. of the 
sample shall be transferred to a small Prlenmeyer flask and titrated with 
0.1 N H.SO,, using methyl orange as an indicator. The weight of the sample 
shall be determined from its specific gravity and the alkalinity reported as 
milligrams of KOH per gram of sample. 


12. Ester value shall be determined for all esters. One to two grams of — ig 


the sample shall be weighed in an ampoule, by first weighing the empty 
ampoule, warming and filling, and then sealing-off and re-weighing. The 
ampoule shall be placed in a 200-ce. Erlenmeyer flask which contains 50 ce. 
of approximately 0.5 N alcoholic KOH. The ampoule should be broken with 
a stirring rod and the flask connected with a reflux condenser. The flask shall 
then be heated on a steam bath for one to four hours, depending upon the 
ester being tested. During the heating the set-up and contents should be shaken 
frequently, taking the usual precautions to lose none of the contents. After 
the apparatus has cooled, the condenser shall be washed down with distilled 
water and three drops of phenolphthalein added to the contents of the flask 
as an indicator. The contents of the flask shall be titrated with 0.5 NV HCL 
Two blanks with alcoholic KOH shall be run along with the sample. These 
blanks should check to the first decimal point. The result shall be reported 
as percentage of ester by weight, allowing in the calculations for acidity or 
alkalinity as determined in Sections 10 and 11. 


NOTE.—An optional method of weighing the sample is in a small weighing 
bottle, removing the stopper after introduction into the flask with a stirring 
rod, or by agitating the contents of the flask. Apparatus with glass joints 
should be used if available. 


13. A copper corrosion test shall be run on solvents and diluents derived 
from coal tar and petroleum. A clean strip of mechanically polished pure 
sheet copper, about 1 in. square, shall be placed in a 4-in. porcelain evaporating 
dish and covered with 100 ec. of the sample. This shall be covered with a 
watch glass and heated on a steam bath for 30 minutes. The liquid shall be 
poured off and the copper examined. for blackening. A slight tarnish shall 
be disregarded, but any marked blackening shall be cause for rejection. 


Se ee oe ae ee 


CHAPTER XXXV 


ANALYSIS OF PYROXYLIN COATINGS 


The writer is indebted to H. D. Bruce of the Bureau of 
Standards and to J. B. Wiesel and Hugo Schlatter for aid in 
the preparation of the schemes of analysis which are presented 
herein. It should be stated, however, that no comprehensive 
scheme of analysis has yet been devised which may be con- 
sidered suitable for all types of nitrate lacquers. In the analy- 
sis of such lacquers, much depends upon the experience and 
ingenuity of the analyst. He must obtain clues as to the in- 
gredients present, and must then devise methods to suit the 
particular mixture at hand. The separation, identification, 
-and quantitative determination of mixtures of organic sol- 
vents, particularly those of similar chemical and physical 
properties, and those yielding constant boiling mixtures, are 
very difficult procedures. The experienced analyst will find a 
physical examination of the lacquer of great value in obtain- 
ing clues as to the identity of the solvent mixture. The deter- 
mination of the specific gravity, viscosity, color, luster or dull- 
ness upon drying, behavior upon flowing on glass or spraying 
on sheet metal, thickness of film obtained, and the detection 
of the various solvents and thinners by odor, will all be of 
great aid in judging the probable composition of a given lac- 
quer. For methods of making physical tests on lacquer the 
reader is referred to Chapter XXXVI. 


In the analysis of lacquers, considerable information may be 
obtained in a preliminary way. The lacquer may be precipi- 
tated by adding an excess of hydrocarbon such as toluol, the 
mass then filtered, and the filtrate evaporated to determine the 
amount of oils, gums and plasticizers present. The residue 
from evaporation may be examined to determine the type of 
oils and gums used. The precipitate which consists of nitro- 
cellulose and pigment may be treated with a solvent such as 
acetone to remove the nitrocellulose, the pigment then being 
examined. The acetone solution of nitrocellulose may then 
be treated with water to throw out the nitrocellulose. The 
above in general is the method used in many laboratories. 


_Itis a difficult matter to determine the percentages of plas- 
ticizers present. Qualitative information, however, may be 


596 Analysis of Pyroxylin Coatings 


obtained by boiling a small portion of the non-volatile residue 
of a lacquer with sodium hydroxide, and then acidifying. If 
tricresyl phosphate is present, the odor of cresol will be de- 
tected and the presence of phosphates may be looked for. If 
the distillate from a lacquer is examined, 1 ec. may be added 
to 1 ce. of water and 1 cc. of mixed nitric-sulphuriec acids. The 
characteristic odor of nitrobenzol indicates the presence of 
benzol as a diluent. 


Camphor is usually present in pyroxylin solutions, in which 
scrap celluloid is used as the base, or in pyroxylin solutions 
when a high boiling latent solvent is needed, such as in mantle 
dips. When more than one or two per cent camphor is pres- 
ent, the camphor content should be determined by the refract- 
ometer. When analyzing a solution which contains scrap cel- 
luloid as a base, about 20% of the weight of the nitrocotton, 
as determined by the total solids determination, should be 
added to the total solids determination in order to get the 
percentage of scrap celluloid used. The camphor type of py- 
roxylin solution is easily recognized after some experience in 
working with such solutions, and it is seldom necessary to use 
the refractometer in evaluating the pyroxylin solution. 


In determining whether a low, medium or high viscosity 
type of soluble cotton was used in the solution, the viscosity 
determination and the nitrocotton content of the solution are 
taken into consideration. From the weight per gallon deter- 
mination and the specific gravity of the distilled solvent, the 
ounces of nitrocotton per gallon of solution may be determined. 


Soluble cotton ranges in nitrogen content from about 11 to 
12.6 per cent, the former being used for celluloid and similar 
plastics, the latter for smokeless powder. Hither of these 
varieties or any in between these two extremes may be met 
with in present day lacquers. The nitrogen content between 
the limits stated) alone is, however, no indication of the suita- 
bility of a soluble cotton for any particular purpose, and it 
may not bear any direct relation to viscosity or solubility in 
any particular solvent. 


In examining the thinner or diluent used in a lacquer, if 
the fruit-like odor of acetates is not noticeable in the various 
fractions, it will not be necessary to run a saponification test. 
In determining the type of resin used, the chart appended on 


Analysis of Pyroxylin Coatings 597 


pages 098-9 may be of general service, as well as the methods 
for oil and resin analysis given in Chapter XXIV. 


Materials to Look for in Pyroxylin Coatings. There is given 
below a list of the more important materials used in pyroxylin 
coatings. While many hundred products have been proposed, 
those listed below are the ones most commonly used. 


Solvents Ethyl, Butyl, and Amy] Acetates; Ethyl Lac- 
tate, Acetone Oil, Methyl-Ethyl Ketone, Fusel Oil, Ethyl and 
Methyl Alcohols, Butyl Alcohol, Acetone, Benzol, Xylol, To- 
luol, Gasoline, Acetic Ether, Acetone Oils, Anhydrous Ethyl 
Alcohol (Ansol), Butyl Propionate, Diacetone Aleohol, Di- 
ethyl Carbonate (Diatol), Ether-Alecohol, Ketones, Methyl 
Acetate, Methyl Acetone, Mono Kthyl Ether of Ethylene Gly- 
col (Cello-Solve), Amyl Aleohol, Butyl Aleohol (Butanol), 
Ethyl Alcohol (Ethanol), Isopropyl Alcohol, Methyl Alcohol 
Methanol), Secondary Butyl Alcohol. 


Plasticizers and Stabilizers.—Diethyl Carbonate, Tricresyl 
Phosphate (Lindol), Diethyl Phthalate, Urea, Camphor, Cas- 
tor Oil, Diamyl Phthalate, Dibuty| Phthalate, Dibutyl Tar- 
trate, Linseed Oil, Rape Seed Oil, Tung Oil, Triacetin, Tri- 
phenyl Phosphate. 7 


_ Oils.—Castor Oil, Linseed Oil, or Rape Seed Oil usually 
in blown or heavy bodied form. 


Resins.—Copal, Kauri, Pontianac, Manilla, Shellac, Damar, 
Rosin, Ester Gum, and Phenol-Colophony or Phenol-Formal- 
dehyde Condensation Resins. 


Cotton.—Usually regular Soluble Nitrated Cotton of low 
viscosity. Smokeless Powder reduced in viscosity and Cellu- 
loid Movie Film are also used. Cellulose Acetate, because of 
its higher cost, is rarely used in commercial lacquers. 

Pigments.—Usually high strength toners, C. P. chemical 
colors, high strength blacks, and finely ground mineral or 
chemical colors of greatest hiding power. 

Schemes for Analysis of Lacquers. —There are given below 
two schemes for the analysis of nitrocellulose lacquers. Both 
have been used quite extensively with satisfactory results. 


LACQUER ANALYSIS (Scheme No. 1.) | — 


Weight per Gallon Determination—The pyroxylin solution 
is adjusted to a temperature of 20° ©., and weighed in a 


598 Analysis of Pyroxylin Coatings 


aprdo]yIvdAja [ UOQ4D) ~|ulH|[alolole|alajole|o 


IYjaaY 111901) alH|Hlalolalolaj|e 


H | A 
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nore toil (= [= [=| [= [= fle led 
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[a= 


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“eatin macdod fo ua) \n|~|0|alalalo|o|ele|e 
word] |o|~|a]o[olololalalole 

wd o|ol=-|-lole ele 


164990 Blol.|ololalalelalelo|- 


SOLUBILITY AND MISCIBILITY OF LACQUER MATERIALS 


wal = [|| [| a | fo] [fle 
pyory Kua) o|~|.lalalalalo|o|8|Ble 

armory ural B | on | op) nlololalalolole 
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aypaking 1kjng = | = cc wa | 0 Ora a 2 Me Fe 

oyory Kma| Bl || falalale Nn a\o le 
amroy ing), | os ~|olalolale|- }2\4|4 
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S/SISISISINISlalelolala 


599 


Analysis of Pyroxylin Coatings 


apldojyIDAJa J. WOGADD| Ay | 


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S 5 S S re ) re S S S = > S 2 S 5 I S =) 
I I d I i SSainoenoes Sooo os 4. Si So Leos I > 
S d S 3 = S 5 S SS) . S S I a S ~ I S I 
S = S S Ss S > iS) 5 S S S S S S) S a 5 5 
=) d = = d = d d d S d > dy ac I S d | SS d 
d SS d Sontcos S S Stal eeeatts hs pasa theo I = I I 
d SS Sled > > ) S S S S S S S S ~ 5 5 
ie i ae a Pee a wd ae oe ewe aoe ke a cos: aie con Rese e ny mele ise Eee os 
SS PORT Spey SR hr eR a ee oe en eee ele a ee 
Woy Sob Se Si Se ses rt Se | Cea eet eae Aimee eee a 
SS ad ed ee Paseo rp on ere ee eta feed ae Pele-be ech [ * 
S. S by > > ~ = eS =~ 5 ~ 
3 2. S Ae is} = Sv Ss = S 
S & > | x gig bie ed ted Ps te eg esha 
= = = S Sates 8 S) ~ S 
Q Q pst =, coy 
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penujuopo—STVIYALVW YANOOVI AO ALITIGIOSIN GNV ALITIANTOS 


600 Analysis of Pyroxylin Coatings 


marked cylinder; the weight of the equivalent volume of water 
at the same temperature being previously determined. 


Weight of pyroxylin solution 


wo 
Weight of equivalent volume of water P S y 


Specific gravity x 8.34 = Weight per gallon 


Specific Gravity—The specific gravity determination is 
made as outlined above or with a pyenometer. The determi- 
nation is made at 15.5° C. . 


Effect on Metal—Much information can be obtained regard- 
ing the non-corrosive properties of a clear lacquer or of the 
solvents to be used in a lacquer, by evaporating 50 cc. in a 
brightly polished spun copper dish. The presence of sulfur 
compounds in the lacquer solvents will be disclosed by brown, 
red or purple stains on the copper dish. The presence of free 
acid in the solvent, usually developed by the hydrolysis of the 
esters, or of free acid developed in lacquers from unstable 
nitrated cotton, will cause a green discoloration. The evap- 
oration may be made on a steam bath. The residue, if any 
is present, may be weighed. 

Free Acidity —Add to 20 gms. of a clear lacquer, with con- 
stant stirring, 40 ee. of a neutralized mixture of 50 per cent de- 
natured aleohol and 50 per cent of water. Then add diluted 
neutralized denatured alcohol until all the solids are precipi- 
tated and the supernatant liquid is clear. This liquid is then 
decanted and the precipitate washed by decantation with a 
small amount of neutralized denatured alcohol. The decanted 
liquid and washings are then titrated with N/10 sodium hy- 
droxide, using phenolphthalein as indicator, until a faint pink 
color persists for at least ten seconds. To neutralize the 
denatured alcohol in the above procedure, add a few drops of 
phenolphthalein indicator, and then N/10 sodium hydroxide, 
drop by drop, with constant stirring, until a faint pink color 
appears. 


Pigment Separation—tThe separation of pigments from a 
pigmented lacquer is usually a very difficult thing. Hven when 
as low as 10 grams of pigmented lacquer are thinned with as 
high as 100 grams of a mixed solvent, and centrifuged for an 
hour, the collodial nature of the lacquer is often such as to 


Se a EN aT Oe eT Oe LT ew NR ee em ee TE AC eee eee eRe ey ee Aa Serene eT ke ashen iis eee anemia 


Analysis of Pyroxylin Coatings 601 


cause some finely divided pigments to remain in suspension. 
Filtering through double layers of filter paper will not remove 
such pigments. For this reason, it is customary in many in- 
stances to ash a 20-gram sample of the lacquer at low tempera- 
ture, first having gotten rid of the volatile constituents by 
evaporation. ‘The residue from ignition may be examined in 
accordance with the methods outlined for the examination of 
pigments in other chapters of this book. Zine oxide, litho- 
pone, and titanium oxide are the pigments usually used in 
white lacquers. 


Total Solids (Method A).—Evaporate carefully, to constant 
weight, on a friction top can lid, a 2 gm. sample of the lacquer, 
Birting occasionally to break ne ‘¢skin’’ which forms at the 
surface upon the evaporation of the solvents. The solid resi- 
due upon evaporation may consist of cellulose nitrate, mix- 
tures of cellulose nitrate, plasticizers, or various resinous and 
oily materials, in the case of clear lacquers, or these various 
ingredients mixed with pigments in the case of pigmented 
lacquers. This method is not as accurate as method B on ac- 
eount of the difficulty of getting rid of the last traces of sol- 
vents. 


Total Solids (Method B).—A sample (5 to 10 grams). is 
weighed out as rapidly as possible in a tared aluminum can 
with a tight fitting cover or by difference from a weighing 
bottle. About 100 ce. of an ether-alcohol mixture (2 to 1) is 
added, and the mixture stirred until a homogeneous mass is 
obtained. The ether-alcohol solution is then brought to a boil 
over a hot plate or a steam bath and 25 cc. of water is added 
very slowly, with continual stirring. The stirring is then 
continued until the solvent is evaporated off. The stirring is 
essential, in order to avoid the formation of collodial precipi- 
tates. If the precipitation is carried out as outlined, a 
stringy precipitate is obtained. <A precipitate in this form 
dries more easily than a lumpy precipitate. The solution is — 
evaporated to dryness on a steam bath, and then placed in an 
oven at 100° C. + 1° C. for two hours; cooled in a dessicator 
for a half (74) hour and then weighed. 


weight of evaporated material in aluminum can X 100 


—= per 
weight of sample 


cent total solids. 


602 Analysis of Pyroxylin Coatings 


If a cloud is formed on the addition of water to the ether-alco- : 


hol solution, the presence of camphor is indicated. When 
camphor is present, it 1s necessary to make two or three addi 
tions of water, evaporating to dryness after each addition in 
order to drive off all the camphor. The percentage of cam- 
phor may be determined by the refractometer. The presence 
of oil in this pyroxylin solution is indicated by an oily feel and 
appearance of the total solids residue. The presence of gums 
is sometimes indicated by the odor or by the dark brown ap- 


pearance and brittleness of the total solids residue. When a 


oils or gums are present, a weighed portion of the total solids 


residue is placed in a paper thimble, and is extracted with a 


solvent in a Soxhlet extraction tube for four hours. Chloro- 
form is a good solvent for Damar, Ester Gum or Mastic, but is 
unsuitable for Sandarac, Cumar or Copal. Benzol is good for 
many resins but unsuitable for Shellac, Sandarae or Copal. 


Butyl Alcohol is the best general solvent to use. The solvent — 


containing the oils or the gums im solution is transferred to a 
tared beaker and evaporated to dryness. Increase in weight 
divided by the weight of the sample times 100, gives the per- 
centage of oils and gums in the total solids. To identify the 


oil or gum used, see methods of oil and resin analysis, else- — 
where in this volume. The acid value, iodine number, and — 
saponification number of this residue will give much informa- — 


tion. 


Volatile Constituents.—Distill a sample of approximately 


150 grams of the lacquer, in steam. Add to the distillate suf- — 


ficient sodium chloride to make a 20% solution of the aqueous 
layer, thus ‘‘salting out’’ certain of the solvents and thinners. 
Separate the two layers, oily and aqueous. Fractionate the 
aqueous layer, which should contain aleohol and acetone, if 


present. The presence of alcohol can be detected in the higher ~ 


boiling fraction. Also look for Ethers of Ethylene Glycol. 
The oily layer is referred to below for further examination. 


Sulphuric Acid Insoluble-—Equal volumes of cold 95% sul- 
phuric acid and the oily layer secured as under determination 
of volatile constituents are placed in a glass-stoppered gradu- 


ated cylinder. The acid should be added very slowly with — 
continued agitation. The mixture is well shaken and allowed 
to stand until there is a complete separation. The volume ~ 
of the upper layer is the amount of distillate insoluble in sul 


Analysis of Pyroxylin Coatings 603 


phurie acid. These are hydrocarbons such as benzol, toluol, 
etc. 


Saponification Value-——Duplicate samples of from four to 
seven grams of the ‘‘oily layer’’ dried over fused calcium 
chloride are weighed into a pressure flask. Fifty cc. of ap- 
proximately normal alcoholic KOH is added. The pressure 
flask is heated in an oven at 100° C. for one hour. It is ad- 
visable to wrap the pressure flask in a towel before placing 
in the oven, as there is danger of explosion. The flask should 
be shaken three or four times while being heated. A blank 
determination is made on the alcoholic KOH at the same time 
as the distillate is being saponified. The saponified material 
in the pressure flasks is allowed to cool, and is then titrated 
with N-2 HCl, using phenolphthalein as an indicator. One ce. 
of N/1 alcoholic KOH is equivalent to 0.008 grams of ethyl 
acetate, or 0.1301 grams of amy] acetate or 0.1055 grams buty| 
acetate. 


If, after deducting the sulphuric acid insoluble portion, the 
saponification number is between 400 and 500, it is probable 
that amyl acetate is the only other constituent of the oily layer. 
However, since butyl acetate is now being used in such lac 
quers, one must not place too much reliance upon the quanti- 
tative analytical data without actually determining the nature 
of the ester present. It must be borne in mind that these 
analytical data are only indiccations as to the nature of the 
materials present. 


Should the saponification number, however, be above 500, 
the presence of esters of lower alcohols is indicated. It will, 
therefore, be advisable to fractionate the oily layer to sepa- 
rate these esters. The fraction distilling below 85° C. is col- 
lected separately from that distilling above 85° C. That pass- 
ing over below 85° C. is probably composed of ethyl acetate, 
gasoline, or benzol, or mixtures of these substances. In the 
absence of ethyl acetate, this fraction should be completely 
insoluble in cold concentrated sulphuric acid. The higher 
boiling fraction is generally composed of amyl or butyl ace- 
tate, or mixtures of both, contaminated possibly by some free 
amyl or butyl aleohol. High boiling hydrocarbons, such as 
xylene, are also occasionally used. The presence of such hy- 
drocarbons can be best detected by their insolubility in cold 
eoncentrated sulphuric acid as outlined above. 


604 Analysis of Pyroxylin Coatings 


After fractionating the oily layer, the sulphuric acid insolu- 


ble portion of each fraction is determined. Saponify each 
fraction by the method above. Deduct from the total amount 
of each fraction the amount of hydrocarbons present before 


calculating the saponification number. This will give an in- — | 


dication of the nature and quantity of the esters present. 
Technical ethyl acetate, which may be present in the lower 
boiling fraction, has a saponification number of 600-635. 


Glycol Solvents.—Since the preparation of Methods 1 and 
2 referred to above, solvents of a glycol base have come into 
the industry. The principal one is the ethyl ether of ethylene 
glycol, known commercially as Cello Solve. The material is 
soluble in water and should therefore be obtained in the water- 
soluble extract in analytical work. In an attempt to deter- 
mine whether a mixture of this material with butyl alcohol 
could be fractionated, the boiling ranges were determined. 
With butyl alcohol, the first drop started at 116° C., and 98% 
distilled over at 118° C. With Cello Solve the ranges were 
from 130.5° C. to 135° C. With a mixture of equal volumes, 


the first drop came over at 116° C. and the last drop at 135° . 


C. 

From these data it would appear that there could be no 
sharp separation by distillation. The densities of the mate- 
rials are 0.936 for Cello Solve and 0.810 for butyl alcohol. 


These might afford a means for distinction and possibly as a — 


basis for analysis. Moreover, it is possible that Cello Solve 


might be converted to glycol and the latter separated by dis- 


tillation, but no convenient method for so doing is at present 
available. The fact, however, that Cello Solve is soluble in 
water may aid the analyst in detecting this material. It has 
very remarkable solvent properties upon nitrocellulose, and 
is practically odorless. 


Tests for Butyl and Amyl Alcohol_—An interesting quanti- 
tative test for distinguishing between butyl and amy] alcohols, 
namely, the Pettenkoffer furfural reaction, is given below: 

A drop of the unknown substance mixed with 5 ec. of water 
(plus ethyl alcohol if the substance is very insoluble) and a 
drop of very dilute aqueous furfural solution, about 0.1 per 
cent, are mixed in a test tube. Several ec. of concentrated 
H.SO, are introduced beneath the aqueous layer. <A purplish 
ring at the juncture of the two liquids results in the presence 


: . ‘ by eee — ‘ er - , 
ee eee rr: S F ar ah iy era Te eee ee - Ec ahi yl a 
see iis rin PN FN ER OE Praline tal OF mo ee é pd ‘Pec hel “ie 4 i oY : 

~ Bn Se OP egy f. i Z 4 na a 


Analysis of Pyroxylin Coatings 605 


of amyl alcohol. This color forms within a period of one 
minute and is quite permanent. A brownish decomposition 
ring should not be confused with the purple-red color. Many 
substances give this color reaction, such as a-naphthol, mor- 
phine, oleic acid, cholalic and other bile acids, but none which 
might be confused with amyl alcohol as a lacquer constituent. 


LACQUER ANALYSIS (Scheme No. 2.) 

Separation of Solids and Liquids.—Weigh out a 400 gram 
sample of the lacquer into a liter flask. Add 400 cc. of water, 
shake thoroughly, and then distill, having the flask immersed 
in a castor oil bath to prevent superheating and consequent 
decomposition. Use a water cooled glass condenser, and a 
large separatory funnel as receiver. Distill only to a tem- 
perature of 100° C. <A higher temperature may decompose 
the nitrocotton. By this steam distillation the solvents are 
separated from the solids. Remove the solids from the dis- 
tillation flask and dry thoroughly at a temperature of 60° C. 
Set aside for later examination. 


Separate the two layers of the distillate. Shake the water- 
insoluble layer with 50 ec. portions of distilled water to remove 
all possible traces of the water-soluble solvents. The water 
solution should not be made over 600 cc. if possible. 


Examination of Water-soluble Solvents.—Look for acetone, 
methyl alcohol, methyl acetate, ethyl alcohol, ethyl acetate, 
butyl alcohol,* soluble high ketones, and ethers of ethylene 
glycol, ete. The water solution of the above solvents are frac- 
tionated through a column as illustrated in Figure—. 

The temperature at which the first drop distills is recorded 
and fractions are cut as follows: 


Ist cut—74° C., acetone, methyl] alcohol, and methyl acetate. 

2nd eut—74°—80° C., ethyl alcohol and ethyl acetate. 

3rd cut—80°—100° C., butyl alcohol, small amounts of butyl 
acetate, and possibly water-soluble ketones. 

Analysis of the first fraction containing acetone, methyl 
alcohol, and methyl acetate is conducted as follows: 

Methyl acetate.—Saponify an aliquot portion of the first 
fraction. Use N/3 alkali. Reflux for 2 hours. Titrate with 
N/3 H2SO,, using phenolphthalein as indicator. 


* Slightly soluble in water. Very soluble in water in presence of ethers 
of ethylene glycol. 


606 Analysis of Pyroxylin Coatings 


CONDENSER 


METAL WATER 
JACKET FILLED WITH 
STILL WATER AND THEN 
STOPPERED 


RUBBER STOPPER 


PIPE WRAPPED WITH TAPE 
OR ASBESTOS INSULATING 
MATERIAL 


sat]| “RON PIPE CONDENSER 
4} /S/NCH IN DIAMETER 

B31 AILLED WITH PEBBLES 

KEPT IN WITH [RON LUG 


GUY 


/-L/TRE COPPER FLASH 


SUPPORT AT FLOOR LEVEL 


FIGURE 199 


Fractionating Column for Lacquer Solvents similar to that used by 
Taylor and by Bruce. 


Analysis of Pyroxylin Coatings 607 


Acetone.—Shake 2 ce. of the first fraction with 300 ee. of 
fresh lime water. Add N/10 iodine solution in small portions 
with vigorous shaking. The acetone reacts to form iodoform 
which erystallizes out as lemon yellow crystals. Make slightly 
acid with dilute H2SO,. At this point a deep brown colora- 
tion should result if sufficient iodine has been added. Titrate 
excess iodine with standard Na2SeOs. 


Reactions. 


2 Ca(OH )2 + 2I2 >Cal? + Ca(Ol)e + 2H20 
3 Ca(OI),. + 2CH3COCH, > (CH;COO).Ca + 2Ca(OH)> 
+ 2CHIs 
(Note: NaOH solution cannot be used in place of Ca(OH):2 water, inas- 


much as certain alcohols which may be present in small amounts react with 
the former in the presence of iodine to form iodoform.) 


Methyl Alcohol.—This may be obtained by difference. 

Analysis of the second fraction (80° C.) containing ethyl 
aleohol and ethyl acetate is conducted as follows: 

Hthyl acetate.—Determined by saponification of a small 
aliquot portion, about 4 or 5 grams. 

Ethyl aleohol.—Obtained by difference, assuming the alco- 
hol solution to be 95% pure, if ethers of ethylene glycol are 
not present. 

The third fraction of the water soluble solvents (100° C.) 
may contain butyl alcohol, butyl acetate, and possibly high 
ketones. Ina separatory funnel, salt out with NaCl in excess 
and add the top oily layer containing the butyl compounds, 
etc., to the water-insolubles. 


Examination of Water Insoluble Solvents.—Look for ethyl 
acetate, butyl alcohol, butyl acetate, amyl acetate, heavy ke- 
tone oils, benzol, toluol, xylol, gasoline, ete. Dry the water 
insoluble solvents with anhydrous granular K2COs or NazSQ,. 

Separation and analysis of the acetates is conducted as fol- 
lows: ‘Take 150 grams of the water insoluble portion, thor- 
oughly dried, and fractionate, using a simple still head. 

Ist cut—107° C., ethyl acetate + other solvents. 

2nd cut—107°—127° C., butyl acetate + other solvents. 

erd cut—127°, amyl! acetate + other solvents. 

Take a 4 or 5 gram portion of each fraction. Add 50 ce. 
N/3 NaOH solution. Add alcohol previously distilled from 
caustic soda to make the acetates miscible with the alkali solu- 


608 Analysis of Pyroxylin Coatings 


tion. Reflux for about 2 hours or until saponification is 
complete. Titrate excess NaOH with N/3 H.SQ,. 


Analysis of the water insoluble portion for ketone oils, and 
hydrocarbon solvents is conducted as follows. Ketone oil.— 
One hundred grams of the water insoluble solvents are re- 
fluxed for 1 hour with 40 grams of phenylhydrazine. The 
ketones form phenylhydrazones. The mixture is then dis- 
tilled to separate the benzol, gasoline, etc., from the phenyl- 


hydrazones and excess phenylhydrazine. If gasoline is pres- — 


ent the distillation must be carried to 175° C. Some decom- 
position of the phenylhydrazones liberating NHs occurs at 
this temperature. The distillate is washed well with water 
and then weighed. The loss in weight represents the ketones 
removed. 


Benzol, toluol, zylol—tThe distillate consisting of alcohols, 
acetates, benzol, toluol, xylol, and gasoline, is shaken in a 
separatory funnel with many small portions of concentrated 
HC! until a constant loss in volume occurs. The concen- 
trated HCl removes the alcohols and acetates. The remain- 


ing benzol, toluol, xylol, and gasoline is washed with water, — 


with dilute Na.COs solution, and again with water. It is then 
dried over anhydrous granular K2COs. The presence of gaso- 
line is easily detected by its odor. If gasoline is not present, 
the boiling point of the remaining solvent is taken to decide 
its nature, i. e., whether benzol, toluol, xylol, or a mixture. 


A | 
Benzol . 2.5.5. ees 0 80° 
Toluol 2... yi we er Dike 
Xylol, about... ....).. 5:0 0 140° 


Gasoline.—If gasoline is present, the mixture of gasoline — 


and benzol is weighed and then nitrated with 3/2 times its 


weight of mixed acid, 30 per cent HNOs, 55 per cent H2SQ,, | 


15 per cent H.O. This nitration of the benzol is carried on in 
- ice water lest the gasoline be acted upon. The layers of the 
nitration mixture are separated, the oily top layer is washed 


with water, dilute NazCOs solution, and again with water. It_ 


is then dried over anhydrous K2CO;. The mixture of nitro- 


benzol, and gasoline is then distilled to a temperature of 175°s 
C. or until a drop of the distillate sinks in water. Gasoline 


Analysis of Pyroxylin Coatings 609 


thus distills over separated from other solvents, and is 
weighed. 

The loss of weight of the last mixture upon nitration gives 
the weight of the benzol. 

Butyl alcohol, amy! alcohol, fusel oil—The quantity of these 
solvents is found by difference. 

95% H2SO, may be used instead of the concentrated HCl, 
in which case the sulfuric solution may be subjected to dis- 
tillation for the recovery of the dissolved solvents. 


Examination of Solids.—The solids left from the steam dis- 
tillation consist of pigment, nitrocotton, and resins. They are 
dried at 60° C. weighed and then examined as shown below. 

Pigment.—Pigment is not present in clear lacquers, but is 
found in pyroxylin enamels. Five grams of the solids are 
weighed and ashed carefully. The residue is analyzed for 
zinc compounds, barytes, titanium oxide, and color pigments 
as in Chapter —. 

Resin.—Ten grams of the solids are extracted in a Soxlet 
for several hours with benzol, butyl alcohol, or some other 
solvent which will dissolve the resin but not affect the nitro- 
cotton. ‘The solids must be crumbled and stirred frequently 
during the extraction to insure complete removal of the resin. 
The extract is evaporated to dryness and the resin residue 
weighed. 

Nitrocotton.—The nitrocotton is satisfactorily obtained by 
difference. 

Resin can usually be extracted from the nitrocotton almost 
completely in the presence of pigment. An alternative method, 
preferably if pigment be absent, is as follows. The solids 
are dissolved in acetone, glacial acetic acid added to dissolve 
the zine oxide pigment, if present, an excess of water added, 
the acetone boiled off, and the precipitated cotton and resin 
is recovered by decantation. The latter mixture is washed, 
dried, again dissolved in acetone or ethyl acetate, benzol or 
butyl alcohol added in excess and the active pyroxylin solvent 
boiled off. The resin remains dissolved in the benzol or butyl 
alcohol, but the nitrocotton is precipitated. The latter is 
filtered off, washed well with ota or butyl alcohol, dried 
and weighed. 

The first step of the paragraph above, glacial acetic treat- 
ment and water precipitation, is.not necessary if ZnO or acid 


610 Analysis of Pyroxylin Coatings 


PHYSICAL PROPERTIES OF SOME LACQUER LIQUIDS 


Spec. Grav. Flash Point Boiling Refractive 


soluble pigment is absent. If a barytes lake is present, it 


15:5/18.5° Cae ate 
PA COCOME, (aio. kao Bie ees 0.79 —0.80 0 56 1.358 
Acetone Oil, light....... A Rate Rea gle 0.8 -0.9 11 140-160 
Acetotre Oi Neary co. oa a 0.9 -1,.2 160-220 
Amy} Acétate!....ds:. 0.5 Dakin eg OOO allot 25.» 426-130 ae eees 
Aryl Alogholc generar eee 0.825 44 121-131 1.408 
Bento 90" kn, Oe eee 0.88 —0.89 80-120 1.50 
Baty! Acetate... a7 coc ree 0.870 24 100-135 1.395 at 25° 
Butyl Alcoholics we ere 0.810 35 110-118 1.396 
Butyl Oxalate 2a 1.01 243 
Buty!) Propionate.... acon dene 0.869 38 120-160 1.398 at 25° 
Butyl Tartrate.004 a ee eee 1.09 203 1.446 
Carbon Disviide:.. carne cores 1,27 =f.29 —20 46 1.620 
Chiorolerin.hs.veis big ee 1.48 -1.49 yy 61 1.449 
Delalin’ 2c o2.. cia necsecone tea eee 0.90 —0.915 57 185-195 1.501 
Diacetone Alcohol..............0.2.., Ride sts 0.91 0.93 163 
Diagaryl Putusiete caso eee 1.025 344 1.488 
Dibuty| Phthalate <a. >. eu, ee 340 1.491 
Ethyl Acetate, tech...) Dep asn 0.81 —0.90 —3 75— 85 1.37 
SHthy) Alcohol. 2. raGnen os eee 0.812 18 76— 79 1.362 
Hihivi cts ees cane a oa 0.719-0.735 35 1.356 
Ethylene Glycol (mono ethyl ether) 0.936 133-135 1.404 at 25° 
“Ethyl Carbonates,.t26.5. ocean 0.979 125 1.385 
Ethyl Lactate. oo nn cee 1.038 125-159 1.411 
Purfurgliis ss keegan eee 1.16 161 1.526 
Fusel Oi Refined 3.) ate 0.83 43 100-133 
Plexalens cai oe i ais beet oe 0.945 68 160 1.468 
Methyl-Alcohol.. 7-23 inn. Ses 0.796 15 66 1332 
Mesity! Oxide. a bnc cannon ye OU e6S 135 1.446 at 16° 
Mineral Spivits 26 .ycnct ee ete 0.76 —0.81 24 130-230 1.41-1.44 
Naphtha, Solvent; light...4.0.s8 0.86— 0.88 21-—23 130-170 1.5 
Picytiienie SA avoir ee eee 0.864 100 160-179 1,487 at 25° 
TT OtPSTM on. ae were pee soe amen es 0.975 78  . 205-209 1.535-1.55 
Tetrilin Extreme 0.900 60 190-205 1.482 i 
Tricresyl Phosphate. tients ty 1.498 at 25° @ 
Potpentitie.; Siig cseneantaunteen 0.86— 0.88 32 150-180 1.465-1.474 
de Los Riveter ity drt pneu Nght CE Sesh Sf) 0.870 7 108-112 1.490 at 25° — 
KX vloloe tee ean eas Mette: eeheeerae cas 0.865 30 130-140 1.499 ‘ 


will be found ultimately with the nitrocotton from which it — 


may be separated by acetone extraction of the nitrocotton. 


The nitrocotton ultimately recovered in this analytical proc- 
ess is quite pure, but its properties will give no indication of 
the viscosity of the cotton as it existed originally in the lac- 


LP wy 


gitar 22, 


Analysis of Pyroxylin Coatings 611 


quer, nor will an analysis of its nitrogen content afford very 
reliable information as to its original degree of nitration. 


Refractive Index of Solvents. —A determination of the 
refractive index of various fractions distilled from lacquer 
solvents will often yield much useful information. Determi- 
nations carried out in this laboratory upon commercial 
samples of lacquer solvents, thinners, and plasticizers are 
shown in Table on page 610. 


CHAPTER XXXVI 
PHYSICAL TESTS ON PYROXYLIN LACQUERS 


Some preliminary information can be obtained regarding 
the usefulness of lacquers by submitting them to physical 
tests. When they are flowed out or spun upon clean metal 
or glass surfaces and allowed to dry, the comparative gloss, 
hardness and tenacity of film can be gauged. If additional 
samples are flowed out upon clean, bright tin plates (5x3 
inches) and allowed to dry overnight, their resistance to 
water can be determined by immersion in a tank containing 
sufficient cold water to cover about two-thirds of their surface. 
The panels should be allowed to remain in the water for a 
period of eighteen hours, then removed and their condition 
noted. They should then be placed back im the tank of water 
and immersed for an additional period of one week, when 
their condition should again be noted. 

Two further sets of tin panels should be coated with the 
lacquers. One set should be allowed to dry in the laboratory 
for a period of six days at room temperature and then bent 
over a mandril. Many lacquers will show cracking, flaking 
and disintegration under this test. The other lacquered panel 
referred to should be allowed to dry for a period of two hours 
and then placed in an oven and baked at 50° C. for. twenty- 
four hours. This should also be submitted to the bending 


test over the mandril. The results of the latter test are % 


generally severe. 

If desired, additional panels may be coated with lacquer 
and after drying for a definite period of time, they may be 
tested with 50 per cent alcohol, 5 per cent aqueous alkali, 
boiling water, or other solutions to determine their resistance 
to these reagents. | 

The tensile strength and elongation of lacquer films are 
determined upon samples prepared by coating tin plates 6x 12 
snches that have been amalgamated with mereury. After 
thorough drying, the lacquer films are removed from the tin ~ 
plates, and placed upon sheets of heavy paper. These sheets 
are placed upon a wooden block, and with a hammer and a 
die similar to that used for cutting rubber specimens, the 
films are cut up into test pieces. These specimens are in the 


613 


Physical Tests on Pyroxylin Lacquers 


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614 Physical Tests on Pyroxylin Lacquers 


form of a dumb-bell. Each end is 26 mm. wide and 26 mm. 
to the beginning of the taper. The central section is 49 mm. 


long by 10 mm. wide. Specimens are broken upon a film- 


testing machine at the end of 24 hours, 72 hours, one week, 
and two weeks. Subsequent to two weeks, it has been found 
that most stripped lacquers become so brittle that they can 
no longer be used for such tests. This latter result may be 
due to the action of the air in coming in contact with the 
lacquer films on both sides, and rapidly affecting their 
strength. The same lacquers, however, when applied to metal 
surfaces and not stripped, may be very durable upon exposure 
tests. 

Roof exposure tests should always accompany physical 
examinations in the laboratory. These tests are made by 
using clean black iron panels 6 x 10 inches, of approximately 
18 gauge. At the upper section of the panel the number 
of the lacquer can be placed with a red grease marking pen- 
cil. The lacquer is then poured over the surface of the panel, 
and by careful manipulation allowed to flow over the entire 
area. The panels are then drained for a period of about 
twenty seconds and then placed in a horizontal position for 
the drying process to continue. Smooth and fairly uniform 
films are thus obtained. The use of the spinning device shown 
on page — is advisable where the exposures are to be made 
on films of any desired thickness. Panels should be placed 
upon the roof of the laboratory at an angle of 45° facing 
south, and should be sprayed daily with water, preferably be- 
tween 12 and 12.30 o’clock. By this method of exposure, very 
rapid results are obtained upon practically all lacquer coat- 
ings. 

The form used by the writer in reporting the physical 
properties of lacquers is shown below: 


Lacquer No. 1 


Composition: 150 grams, (32 oz. Butyl Acetate solution; 25 
grams Toluol; 25 grams Benzol; 25 grams Ethyl Alcohol; 25 
grams Ester Gum Solution (50-50 in Benzol); 25 grams 
Damar Solution (50-50 in Benzol). ; 

Film Appearance: O. K. | 

Cold Water Test: 18 hours, O. K. 1 Week, O. K. 

Bending Test: Dried at Room Temperature. Badly chipped. 


Physical Tests on Pyroxylin Lacquers 615 


|S EE A NT ES TE ST TS IDE LOS LEIA ELLIE. 
EXPOSURE TESTS ON LACQUER PLASTICIZERS 
SERIES E. 


In this series the lacquers contained no resins. They were made up with 100 

parts by weight of a 32 oz. Butyl Acetate Solution of 144 second viscosity 

Nitrocellulose, 70 parts by weight of Toluol, and 10 parts by weight of the 
plasticizer noted. 


Panels exposed Feb. 24, 1927. 


Rating on 
April 8 May 24 General Observations 
; ee Rust under film in 4 weeks. Rusts 
ee ElMeTicizer =... ss... 5 0 through in 12 weeks. 
Be Rust under film in 4 weeks. Rusts 
a a 4 0 through film in 5 weeks. Failed. 

Entire panel covered with rust in 4 
Benzyl Alcohol ......... 3 0 SAL aie hinted: 

Rust under film in 9 weeks. Rusts 
eee ezonte” .---.-- . through in spots after 12 weeks. 

‘ Rust under film in 4 weeks. Rusts 
PIE VIGEsLTOLG™.......-s.. 4 3 through. in 12. weeks. 
Film practically O. K. in 12 eweks, with 
Butyl Phthalate ........ 10 9 but few rust spots under film. Gloss 
excellent. 
é : Rust under film in 4 weeks. Rust 
"Duty! Propionate ....... 4 4 through film in 9 weeks. 

Rust under film in 4 weeks. Rust 
ie 2 s through film in spots in 12 weeks. 
“a Rust under film in 4 weeks. Rust 
ME eg es on ose 7 3 through film in 9 weeks. 7 
Take ‘ Rust under film in 4 weeks. Rust 
Semper Oil... ce eee 6 3] ro aaiiininine a eek 
Di Film intact after 12 weeks but slight 

Bee alate ...--- 2 9 rust under film. Excellent gloss. 
i Film fairly intact in 12 weeks. Some 
Dibutyl Phthalate ...... 9 9 rust through film in spots. Excellent 
gloss. 
: Rust under film in 9 weeks. Film in- 
Diethyl Phthalate ...... 9 8 tact at end of 3 months. Excellent 
gloss. 


3 Rust under film in 4 weeks. Heavy 
rust; through film in 8 weeks. 


Mievavine ............... Rust under film in 4 weeks. Heavy 
ES Saad . 3 rust through film in 8 weeks. 


Rust under film in 4 weeks. Consider- 


Ethyl Acetyl-Glycolate .. 5 


Panseed Oil ............ 6 6 able rust under film at end of 12 
weeks but film sound. 

EG yh os vo ieis ow es 2 0 Film peeling off after 5 weeks. Failed. 

i 0 © Rusts through film in 1 month. Failed. 

ME i ke ak ee O O Film scaled off in 1 month. Failed. 

Tricresyl Phosphate .... 10 7 Sound after 11 weeks but checked dur- 


ing twelfth week. 
Rust under film after 5 weeks. Con- 
CA a 9 7 siderable rust under film at end of 
12 weeks, but film remains sound. _ 
( Rust under film after 5 weeks. Con- 
oe 9 ih siderable rust under film at end of 
12 weeks but film sound. 


616 Physical Tests on Pyroxylin Lacquers 


Relation of Strength and Exposure Tests —The writer 
has attempted to correlate tensile strength and elongation 
tests on stripped films, with exposure tests. The table below 
presents the tensile strength and elongation of all the lacquers 
in Series E. It would appear that in every case where fairly 
eood resistance to weathering was noted, the films were orig- 
inally of good tensile strength and fairly good elongation. 
Films which showed very high tensile strength and very low 
elongation, or very low tensile strength and high elongation, 
as a rule, did not stand up as well in the weathering tests as 
those previously referred to. A chart of the results is given 
below. 


PHYSICAL TESTS ON STRIPPED LACQUER FILMS AS USED IN 
SERIES E. 


-—24 Hours— —48 Hours— —1 Week— 
Elonga- Elonga- Elonga- 
tion Tensile tion Tensile tion Tensile 
% Strength % Strength % Strength 


No plasticizer 2.4.7, 4 see eee 0. 675 Q- 25 QO 725 
Acetaniiig leis caus a ee ee 8S 408 S 405 7. Bao 
Benzy! Alcohol 38 ss.cis ace ele oe 3 600 8 480 8. Bou 
senzyl: (‘Benz0ate: 2... s5 aus eee ce 8 6) Oe 2 - 833 2 Sok 
Butyl: Butyratey nx ea eee 4 440 4 540 2 540 
Butyl Phthalate’ wc oye ae 6. -38zZ8 6. 308 6 344 
sUtY].. Propionate’. . 2% va eee 2 Soe 2 480 2. 600 
Butyl “Lartrate*.. Avs See eee 4 $98 4 885 2. 318 
Camphor >: Gta its tae eee eee 4 350 4 400 Se Ss: 
Camphér Gili... me ae mee ee ee 4° 580 3: 500 1 400 
Diamyl. Phthalate. .c: 6.5 ee 3. ~ 800 3 -. 280 J "..306 
Dibutyl “Phihainten. oven snare eee 38 384 2 240 Ou ee 
Diethyl Phthalate: «Zeke awit eee 2° Boe Pie 8 ao Ore 
Ethyl Acetyl Glycolate....:5....0%% 8 440 1. 420 AP 
Hexaline. oo: ce nc eekh ba e ee 2 480 2 380 1 420 
Linseed Olle oe eee 10 250 8. 49255 5.” 2 ve 
Pine “OU. ee eae ee 6. "3a 3 418 a0 aU 
Totralin. i208 cat ete ee een et 3. 560 o.4 OO 1 400 
BV MOL cai ase oo io Sd oer er 7 460 4 420 3 470 
Tricresyl Phosphate =... 26. sree 5 ©6400 5 gen 5 400 
Taig Oat yee heen suet ine eae es 1. SOS 6. “300 5. 260 
Castor: Oile vaca os ots aon eens 6 . 320 3 390 3 460 


Films were stripped 1 hour after application, cut into test specimens and 
tested at three periods. Tensile strength figures are in kilograms per square 
centimeter. 


CA a ee | 


‘ 
; 
a 


a. eee Se eT ee 


-” 


Physical Tests on Pyroxylin Lacquers 617 


Large cracks. 
After Baking at 50° C. Chipped off. 

Roof Exposure: 15 days, some corrosion showing at edges. 
whole rusting from under side. 30 days, much corrosion 
and flaking. 

STRIPPED FILMS 
Tensile strength  Hlongation 
kg. per sq. cm. per cent 

Palmetests at 24 hours ........... 73 1 

Film tests at 48 hours Too brittle. 

Test discontinued. 


Lacquer No, 2 
Composition: Same as No. 1, plus 20 grams Tri-Phenyl Phos- 
phate. 
Film Appearance: Good. 
Cold Water Test: 18 hours, very slight bloom. 1 week, sheht 
bloom. 
Bending Test: Dried at Room Temperature. Badly Chipped. 
Large cracks. 
After Baking at 50° C: Chipped off. 
Roof Exposure: 15 days, some corrosion at left edge, other- 
wise O. K. 30 days, slight corrosion. Dull but fairly 
sound, . 
STRIPPED FILMS 


Tensile strength Elongation 


kg. per sq. cm. per cent 
femeeerta at 24 hours ......... PME 56 
Pimme tests at 48 hours ......... 60 19 
Meets at l week ........... 100 7 
Meme tests at 2 weeks .......... 85 7 


Low Temperature Test on Lacquer Coatings. One method 
of test which the writer has applied is to submit lacquered 
panels, either before or after weathering, to the effects of 
low temperature. If, for instance, the panels are taken from 
a roof exposure test or from an accelerated ultraviolet light 
cabinet and placed in a refrigerator having a temperature of 
—20° C. (Frigidaire or other ice making equipment), the 
coatings may crack or flake off if they are not sufficiently 
distensible. If an ice making equipment is not convenient, 


618 Physical Tests on Pyroxylin Lacquers 


there may be used a solution of solid carbon dioxide dissolved 
in ethylene bromide or chloride. With such a mixture, 
temperatures as low as —70° C. may be obtained. Small 
panels may be dipped into an insulated container of the 
solution. After immersing the panels for about one minute, 
they may be withdrawn, allowed to assume normal tempera- 
ture, and then examined. 


Testing the Resistance of Lacquers to Bending.—In test- 
ing varnish for what is termed ‘‘elasticity,’’ the Kauri gum re- 
duction tests is used, a sample of varnish being made more 
brittle by the introduction of a definite amount of ‘‘run’”’ 
Kauri. The sample is baked upon a panel and then bent 
over a mandril. It has been found that a somewhat similar 
test may be applied to lacquers, the elasticity of which is 
probably a component of the tensile strength and elongation. 

For such a test this laboratory uses two solutions, one of 
which adds to the resistance of a lacquer (addition solution), 
while the other (reduction solution) decreases the resistance 
of the lacquer to the bending test. Lacquers of good and poor 
physical properties may therefore be included. 

The addition solution for extending the ‘‘elasticity”’ is 
made up of 90 parts by weight of commercial butyl acetate 
and 10 parts by weight of tricresyl phosphate. The reduc- 
tion solution for reducing the ‘‘elasticity’’ is made up of 1 
part by weight of run Kauri gum and 2 parts by weight of 
commercial butyl acetate. The same method of making the 
run Kauri is followed as for the preparation of run Kauri 
for varnish tests. 

Butyl acetate is used in both the addition and reduction 
solutions in preference to toluol or to other hydrocarbons 
because many lacquers will not withstand the further addi- 
tion of hydrocarbons without throwing the nitrocotton out 
of solution. 

In operating the tests, the non-volatile of the laequer is 
first determined and the amount of solution to be added is 
based upon the non-volatile. To 100 parts by weight of the 
lacquer there is added an amount of the addition solution 
equivalent to 10% of the non-volatile and to another 100 
parts by weight of the lacquer there is added an amount of 
the reduction solution equivalent to 10% of the non-volatile. 
Thus, for instance, if a lacquer contains 40% of non-volatile 


Physical Tests on Pyroxylin Lacquers 619 


material there will be added to 100 grams of the lacquer four 
grams of the addition or of the reduction solution. The pan- 
els used in this test are made of tin and are three by five 
inches, the same type as used in the Kauri reduction test. 
Upon the central portion of the panel is flowed a sample of 
the lacquer to be tested that has not been reduced. On the 
left-hand side is flowed a sample of lacquer extended with 
the addition solution and on the right-hand side a sample of 
the lacquer reduced with the reduction solution. The panel 
is dried under normal conditions in the laboratory for a period 
of thirty minutes and then placed in the oven at 50° ©. for 
one hour. The panel is then taken out-of the oven and 
allowed to cool to 25° C. and is then bent over a mandril 3 
mm. in diameter. The condition of the three lacquer samples 
upon the panel is noted. Thus, for instance, the panel of the 
straight lacquer in the middle and the one that has been re- 
duced with Kauri gum solution may both show cracking 
while the one that has been extended with the tricresyl phos- 
phate addition solution may remain in perfect condition. 


Spray Test.—Lacquers should be tested to determine their 
properties when used in a spray gun such as is employed in 
automobile finishing plants. The amount of diluent required 
to thin the lacquer to suitable consistency for spraying, should 
first be determined. After the gun has been regulated and 
the proper pressure obtained to deliver the lacquer in a mist 
form, the test can be conducted upon large size panels (ap- 
proximately 24 x 36 inches). The resistance of the lacquer to 
formation of ‘‘orange peel’’ effects should be carefully noted. 
The test can be conducted in a room where there is consider- 
able dampness, if a determination of the ‘‘blushing’’ resistance 
is important. Lacquers which contain a very high percentage 
of low boiling point solvents very often show ‘‘blushing’’ or 
whitening tendencies. The finished panel should then be 
polished to determine whether polishing will remove the 
‘“‘blushing’’ and produce a smooth, uniform surface. The 
degree of resistance to polishing should be carefully noted as 
it will give information as to whether the right type or amount 
of resin has been incorporated in the lacquer. 

Brushing Tests on Lacquers.—Household lacquers are de- 
signed for use with a small brush. In making a test of such 
lacquers, it is desirable to apply them to filled wooden surfaces, 


620 Physical Tests on Pyroxylin Lacquers 


to black iron panels, and to wooden surfaces that have previ- 
ously been finished with varnish or paint products. Old chairs 
finished with mahogany varnish stain form an especially good 
type of surface upon which to test these lacquers. It is usual 


to scrub the surface lightly with a rag saturated with gasoline, g 


and then apply the lacquer in rapid strokes, keeping the brush 
well filled. After finishing the object, the surface should be 
examined to see if it is uniform in appearance and whether 
the solvents in the lacquer have raised the underlying films of 
paint, varnish, or other surfacing material over which the 
lacquer has been applied. The surface should also be examined 
for evidences of ‘‘bleeding’’ through of the organic colors 
usually employed in the underlying wood stains. A recoating 
test should also be made to determine whether the brushing 
lacquer will produce a uniform, smooth coating when applied 
in two coat work over the test surface. 


Sanding Test on Lacquers and Surfacers.—Croll and Jenkins 
of the Pittsburgh Plate Glass Co. have worked out two 
methods of test which they have found equally satisfactory. 
The first step in each test is to spray a measured amount of the 
surfacer over primed or bare metal, drying the panei under 
the conditions the surfacer is to meet and then applying the 
sanding test as follows: | : 

a. Weigh the panel, sand a given number of strokes evenly 
distributed over the whole panel, wash off, dry and weigh 
again. The panel should be given some time in a warm 
place to dry after sanding in order to remove absorbed mois- 
ture from the surfaces. Repeat and take an average. 


b. Use a sanding block, about 2” by 4° and with uniform 
pressure and plenty of water sand through to the metal count- 
ing the number of strokes. Practice will make one quite pro- 
ficient at giving a uniform pressure and if the test is run in 
triplicate and an average taken a fairly accurate determina- 
tion is obtainable. : 

P. P. G. Paper Curl Test for Lacquer.—P. R. Croll has sug- 
gested the following test as an indication as to whether the 
proper amount of plasticizer has been added to a lacquer. 

The lacquer product is sprayed on a standard 6° by 8° card 
(Velvo, 110 lb. per ream, enameled paper has been found 
satisfactory) and dried under the conditions the product is to 


meet. Lack of plasticiezr evidences itself by a very pro- — 


TE, ee 


Physical Tests on Pyroxylin Lacquers 621 


nounced contraction of the lacquer on drying and a conse- 
quent strong curling of the paper. This test if carefully made 
is an excellent check upon the condition of the finished pro- 
duct. 


Testing Lacquer Enamels for Physical Properties —A 
group representing Sub-Committee XXV of Committee D-1 
of the A. S. T. M. has suggested the following tests to the 
members of the Committee who are carrying on cooperative 
work in this direction: 


The samples should be kept in very tight cans and thor- 
oughly stirred before making any determination. 


Weight Per Gallon.—At least one pint of liquid, accurately 
measured, shall be weighed at a temperature of 20° C. The 
result shall be expressed as pounds per gallon. 


Non-V olatule Matter.—Method for Varnishes (A. S. T. M. 
standards, 1924—p. 826) shall be used except that heating 
for one hour is sufficient. 


Viscosity—F or comparative purposes, any apparatus de- 
signed for heavy liquids is satisfactory; for comparison with 
other laboratories the Gardner ‘‘Mobilometer’’ is suggested. 


Drying Time.—F low sample and standard without thinning 
crosswise on a clean 4° by 8” glass plate. Allow to dry ina 
nearly vertical position. Examine for drying and hardness 
after 15 minutes, 1 hour and 24 hours. The drying shall be 
judged by touching or pressing the films with the finger and 
the hardness by scratching the films with a penknife. 


Fimeness.—The panel prepared for the Drying Time test 
shall be examined by reflected light and transmitted light for 
fineness of grinding and freedom from large particles. The 
sample shall be equal to the standard. 


Gloss——The panel prepared for the Drying Time test shall 
be examined after 24 hours for gloss. The sample shall have 
the same degree of gloss as the standard. 

Color.—The panel prepared for the Drying Time test shall. 
be used for the determination of color. A preliminary exami- 
nation for color may be made after drying one hour, but the 
final examination shall be made after 24 hours. The sample 
shall match the standard. | 


Working Test.—The methods as outlined are primarily for 
the testing of Lacquers and Lacquer systems on steel. The 
test panels shall be 8x12” (unless other size necessary for 


622 Physical Tests on Pyroxylin Lacquers 


test purposes) made from ‘‘fender stock’’—a cold rolled 18 — 
gauge sheet. 

The panels should be thoroughly sanded with No. 180 sand 
paper and finally cleaned by immersion in 90% Benzol twice, 
allowed to air dry five minutes before applying primer coat. 

Metal primers shall be applied and dried or baked accord- 
ing to manufacturer’s directions, noting general appearance 
and smoothness. Tests to compare primers only shall be made 
by coating standard panels with primers to be compared, fol- 
lowed by standard top coat lacquers. Similarly, surfacer coat 
material shall be compared over a common primer and under 
a common standard lacquer. 


For testing a complete lacquer system, the coats shall be 
applied as directed by the manufacturer with the drying tem- 
perature and time elapsed between coats carefully regulated. 


To assist in getting uniform spray coats the following is 
offered: ‘‘A spray coat that is uniform and representative of 
the material may be secured by adjusting the spray gun to 
maximum width of fan and securing a uniform density of 
spray; with the gun about eight inches from the surface, a 
uniform stroke shall be used at such a speed to allow maxi- 
mum wetness of film without sagging; each successive stroke 
shall lap one-half of the film applied by the former stroke.” — 
‘After final coat is dry (at least twelve hours) one-half of the @ 
panel shall be water sanded with No. 400 sand paper and pol- 
ished with rotten stone and water. At least four panels shall 
be prepared for each test, and more are preferable. 


Exposure Test.—At least one panel shall be exposed out- — 
doors on a regular exposure rack and examined at regular 
intervals for color, gloss, ete., and compared to a similar panel 
retained inside according to standard practice. 


Adhesion.—A test panel shall be prepared for primer as — 
described previously. A full coat of primer is applied and © 
while still wet a piece of silk voile or bolting cloth, previously — 
washed and ironed, is allowed to sink into the wet primer with 
an inch or two of silk projecting from one end of the panel. 
The primer is dried in the regular way. When dry, a safety 
razor blade and steel straight edge are used to eut through 
the primer and silk down to the panel in 14” parallel strips. 
By pulling the loose ends of the silk the strips may be removed 
from the metal one at a time. From the pull required and the — 
character of the patches of primer left on the metal, the com- © 
parative adhesion of any set of primers may be determined — 
with considerable accuracy. 


Physical Tests on Pyroxylin Lacquers 623 


Bending Test.—A one inch strip cut from the test panel 
shall be clamped in a vise, the upper jaws of which are rounded 
with a radius of 44”. The surface may be protected by paper 
or cloth. The strip shall be bent over the corner of the vise 
to an angle of 90° and the surface examined for failure. The 
number of bends till failure occurs may be determined, if 
desired, by straightening the strip and bending back as many 
times as necessary. A mechanical attachment on the vise for 
gripping the top of the strip and insuring a uniform bend is 
desirable but not essential. 


Printing Test—A test panel shall be covered with two 
pieces of ordinary cheese cloth. On the cheese cloth shall be 
placed a piece of felt about 3/32” thick. A definite weight of 
about 1 lb. per square inch shall be placed on the felt. This 
may easily be obtained by filling a quart can with white lead 
till the desired weight is attained. The surface should be 
examined in 24 hours, and longer, if desired. No printing 
should occur at room temperature. 


Tensile Strength and Distensibility of Film.—A_ sheet of 
tin plate (12 x 16 inches is a convenient size, and .019 inch a 
convenient thickness) is amalgamated with mercury. This 
is done by pouring a few drops of mercury on the center of 
the panel and with a piece of cotton waste, spreading the mer- 
cury toward the edges of the panel. The smallest amount of 
mercury required to accomplish the purpose should be used. 
After amalgamating the panel all excess mercury should be 
wiped off. (The mercury should be used and the amalga- 
mated plates stored only in a well ventilated room. Opera- 
tors should be cautioned against getting the mercury in con- 


tact with food or anything by which it might be carried into 
the mouth.) 


The lacquer or lacquer enamel to be tested should be thor- 
oughly stirred and strained. It may be either sprayed or 
flowed, in one coat, on the amalgamated panels. If the ma- 
terial has been flowed on, the panels should be set on end about 
15° from the vertical so the excess material may flow off the 
panel. This should be done in a well ventilated room or eabi- 
het maintained at fairly uniform temperature and humidity 
conditions. | 


After allowing the films to harden for about four hours, 
they should be stripped (brittle films might have to be stripped 
as soon as they are sufficiently solid to be handled). The films 
are easily removed if a spatula is run around the edges be- 
tween the film and panel. 


624 Physical Tests on Pyroxylin Lacquers 


The films are cut to test shapes by means of a die of suita- 
ble dimensions (see Proceedings A. S. T. M., Volume 21, 1921, 
Page 1111, ‘‘Stress-Strain Measurements on Films of Drying 
Oils, Paints and Varnishes’’). The average thickness of the 
test shape is measured most conveniently by using a stick mi- 
crometer and taking the average of about five readings over 
the constricted portion of the test shape. The thickness should 
be written on each test shape, as well as some identifying num- 
ber or letter. The test shapes that are to be tested and com- 
pared at any certain age should be of the same thickness or 
nearly so. They should not vary more than + 01 mm. if 
the films are less than three weeks old (unless the film is 
under .05 mm. thick). If the films measured have been aged 
a longer period they may vary + .02 mm. without appreciably 
affecting the results. These limits must be held close on 
fresh nitrocellulose films, since the retention of volatile by 
the films varies with the thickness of films as well as the 
amount and nature of the volatile. 


The thickness measurements being completed, the test 
shapes should be placed in a well ventilated cabinet main- 
tained at about 28° C. Two days before a test is desired, the 
required number should be taken from the cabinet and placed 
in a humidor (an ordinary dessicator with H.SO, solution of 
proper concentration) maintained at approximately 50% rela- 
tive humidity at 23° C. (73° F.). This relative humidity can 
be approximated with a H.SOs—water mixture of 1.33 specific 
gravity at 23° C. (73° F.). (See Ria Wilson—Aq. Vap. Pr. 
and Density of H.SOx Solution as a Function of Temperature 
—_J, Ind. Eng. Chem., Volume 13—No. 4 (1921).) While the 
relative humidity does not affect nitrocellulose films as much 
as it does oleo-resinous films, it may affect them to a greater 
or lesser degree, depending on the constituents of the film. 


The temperature of the room in which stress-strain meas- 


ee 


urements of nitrocellulose films are carried on should be kept | 


at 23° C. + 2° (Approximately 69 to 76° F.), since variation 
in temperature affects the distensible properties of these 
films. 

Enough test shapes should be provided so that checks can 
be obtained. Five test shapes are usually sufficient, except on 


an exceptionally hard and brittle film. It 1s usually the case — 


that the curves coincide but differ more or less as to the ulti- © 
mate breaking point. This is due generally to unavoidable ~ 


_—-" 


minute flaws along the edges of the test shape and it is, of a 


course, permissible in this case to choose the curve which broke 


under the greatest load. In cases where the curves of the — 


Physical Tests on Pyroxylin Lacquers 625 


same film do not coincide, even after running a number of test 
shapes, it is advisable to choose that curve which most nearly 
represents the mean of all the curves. 

The results may be recorded as a complete stress-strain 
curve or as ultimate elongation and ultimate load expressed 
in per cent elongation and load in grams (or kilograms) per 
square centimeter. 

The stress-strain apparatus used shall be sufficiently sensi- 
tive to reveal significant differences in the softest films en- 
countered in ordinary testing. Suitable machines are de- 
scribed in P. M. A. Scientific Section, Circular No. 240 and 
Broo. |. M.. Volume 21, 1921, Page 1111. 

Miscellaneous Physical Tests.—Viscosity, hardness, adher- 
ence, durability, brittleness, permeability to water, gloss, re- 
sistance to abrasion, toxicity, contraction of film and speed 
of drying are other physical characteristics that might be 
determined. Many of these properties have already been 
discussed in this and in Chapter XVIII. 


Testing the Flashing of Lacquer Vapors.—In order to 
secure some information regarding the possible danger of 
lacquer vapors flashing in finishing shops if open flames are 
brought into the room, a series of preliminary tests have been 
made. In designing these tests, it was thought that lacquers 
containing high boiling solvents would prove much safer in 
this respect than those containing low boiling solvents. 

The laequers selected for the purpose all contained 16% 
by weight of % second viscosity nitrocellulose and 84% by 
weight of solvent. In the first five lacquers, single solvents 
were used in every instance. In the remaining seven lac- 
quers, mixtures of equal parts by weight of high boiling and 
of low boiling solvents were employed.* 

The apparatus designed for this purpose is shown in Fig. A. 
It consists of a galvanized iron chamber to which heat is sup- 
plied by a 100-watt Mazda lamp inserted in the lower por- 
tion of the chamber. Above the lamp is a long trough hold- 
ing a boat containing the lacquer under test. The apparatus 
is so arranged that the boat may be filled and pushed back 
into the cabinet directly above the lamp. The trough extends 
out for a distance of 36” from the heating cabinet, and every 
inch is perforated with a small circular opening %%” in dia- 


*Practical consideration makes it necessary in many instances to have some 
low boiling solvents present in lacquers. 
See also “A Study of the Explosive Properties of Lacquer Solvent Vapors,” 
by E. G. Richardson and C. R. Sutton, to appear in Jour. Ind. and Eng. Chem., 
early in 1928, 


"-squaajog sonbowy Jo Nogeg oapervdwoy omy Suymymsojoq 10s suywrvddy womodxy ahi 
TOS] FHOO Ly ‘ 


=< = ) 


Lag ree pled Patt ad PAZ ork i, 


IRSNSSSSBG 


fa CBF 


—w =) 


Physical Tests on Pyroxylin Lacquers 627 
i eet 


meter. The flame employed is about the size of a match 
head. During the test only one opening is used, the others 
being kept closed with corks. The top of the heating chamber 
and the trough are covered with a thick sheet of safety wire 
glass. 

The method of operation is as follows: The temperature 
in the chamber is first brought to equilibrium, which ranges 
from 95° to 110° C. <A charge of ten grams of lacquer is 
placed in the boat which is then inserted into the end of the 
trough and pushed back into the chamber above the lamp. 
The first test is a trial one, in which the flame is brought to 
the hole at one minute intervals. In repeat tests the flame 
is not applied until one minute less than the time required 
for the trial flash has elapsed. The intervals for flame appli- 
eation are then reduced to 15 seconds. The tests on a group 
of lacquers should be carried out during the same day in 
order to get closely checking results. After every test the 
trough is swept out with a current of air. 

The results of the initial tests suggested that the flash 
point of the vapors which formed explosive mixtures with 
air seemed to vary directly with the boiling range and indi- 
rectly with vapor pressure of the solvent used in the lacquer. 
Solvents of low boiling point and high vapor pressure flashed 
in a shorter period of exposure than those of high boiling 
point and low vapor pressure. 

The tests were made at Holes Nos. 1, 20, and 30, the latter 
hole being approximately 30 inches away from the heating 
chamber. Some of the lacquer solvents which contained no 
Jow boiling materials did not flash even after 30 minutes at any 
of these holes. 

Tests might also be made by using an electric spark instead 
of an open flame. It is believed, however, that in general, 
comparable results with those obtained in this work would 
be shown by such elaborations. | 

Testing the Latent Heat of Vaporization of Lacquer 
Solvents. When a liquid evaporates,* there is a consequent 


**“Cold Due to Evaporation—Whatever be the temperature at which a 
vapor is produced, an absorption of heat always takes place during vaporisa- 
tion. If. therefore. a liquid evaporates. and does not receive from without 
a quantity of heat equal to that which is expended in producing the vapor, 
its temperature sinks. and the cooling is greater in proportion as the evapora- 
tion is more rapid. * * * If a little water is placed in a test-tube. which 
is then dipped in a beaker containing some ether, and a current of air is 
blown through the ether by means of a glass tube fitted to the nozzle of a 
pair of bellows. the rapid evaporation of the ether very soon freezes the water 
in the tube. Richardson's apparatus for producing local anaesthesia also 
depends on the cold produced by the evaporation of ether. The lowness of 
the temperature obtained depends not so much on the magnitude of the latent 
heat of vaporisation of the liquid as on its volatility and on the rapidity of 
the conversion.”—Ganot’s Physics. 


628 Physical Tests on Pyroxylin Lacquers 


FIGURE 202 


Apparatus used to determine loss in temperature. Dish finally used 
one-half size of above. 


Physical Tests on Pyroxylin Lacquers 


Isopropy| Alcohol - 
Ethyl! Alcohol 


Benzol 
Ethy! Acetate 


Butyl Acetate 
Buty! Alcohol 
Amy| Acetate 


Toluol 


Hl Mn 
LT a a 
Sv 
SU A AL 
AU 


240 


. 120 150 180 210 
Time in Seconds 


Curves showing loss in temperature of single solvents when treated as described above. 


t ies Ou aert. 97 
Be aus) 5921639 ‘Qunjeuedwa} ul SSsO7 


FIGURE 203 


630 Physical Tests on Pyroxylin Lacquers 


O 
N. 
Cc. 
0) 

o@) 

O ONe) Ol a O OO 
of 8h FB SRB oO 
AY) 

(0 

aes 

rd) 
O 

< 

Son = 
=) 

aa) 

(oe) O00 
Ko) TAR 


TIO 
SUID R AS ERREYIE ED 
PEL A 
a 
CC 
AY 
MUTA LAV ZL 


HALL te 
WATT 
17 ZZdS a 


B/E 


when treated as described above. 


PUL 
oO Oo C 


apaibhiee "SoaIbaq ‘qunyeioduia) ul "SSO} | 


TIGUR 
of Butyl Acetate-Benzol mixtures 


temperature 


g loss in 


Curves showin 


Physical Tests on Pyroxylin Lacquers __ 631 


reduction of temperature of the surrounding atmosphere. If 
this reduction in temperature is very great, the dew point of 
the atmosphere is reached, and water is precipitated. If the 
drying of a film of nitrocellulose lacquer is too rapid, because 
of the presence of large quantities of quick evaporating 
solvents, the temperature is reduced, and water is deposited 
on the film. The nitrocellulose present, being insoluble in 
water or in solvents containing an appreciable quantity of 
water, is thrown out of solution and appears as a cloud on 
the surface. This is commonly known as ‘‘blushing.’’ The 
cooling effect referred to may be noticed by coating a metal 
plate with a rapid drying lacquer, and holding the hand on 
the reverse side. It was thought that this cooling effect could 
be measured in a way which would give comparative results 
and afford information of value to lacquer manufacturers. 
Accordingly, a study has been made at this laboratory on the 
reduction of temperature caused by the evaporation of various 
solvents used in the manufacture of pyroxylin lacquer coat- 
ings. The solvents to be used were first placed in a water bath - 
and allowed to come to a'constant temperature, namely 20° C. 
This was done in an effort to make the conditions of the test 
comparable. A glass dish (5 cm. in diameter and 3 em. deep) 
was then filled with the solvent to be tested. An eight-inch 
electric fan was placed six inches from the dish so that the 
draft would blow directly over it. The fall in temperature 
was determined by means of a thermometer graduated in 
tenths of a degree C. Simultaneously with the switching on 
of the electric fan, a stop watch was started and the results 
_ noted at half-minute periods for a total of six minutes for 
each sample. The results have been reported in chart form 
below, and curves have been prepared, showing these results 
in a more graphic manner. 


Testing the Vapor Pressure of Lacquer Solvents.—The vapor 
pressure of a liquid is the pressure of the vapor when in con- 
tact with the liquid. When this pressure becomes equal to 
that of the pressure of the atmosphere, the liquid may be 
said to boil, and it then passes rapidly into a vapor. When 
this pressure is further increased above the pressure of the 
atmosphere, the liquid passes more rapidly into the vapor 
state. 

Vapor pressure curves are usually plotted with the tem- 
peratures on the ordinate and the pressures on the abcissa. 


b> 7 


632 Physical Tests on Pyroxylin Lacquers 


These curves have a two-fold meaning. ‘They show not only 
the vapor pressures of a liquid for a large number of tempera- 
tures, but also show the temperature at which the liquid can 
be said to boil for various pressures. For example—A cer- 
tain liquid at 90° C. has a vapor pressure of 590 millimeters 


FIGURE 205 


One type of apparatus used to determine 
vapor pressure by the statical method (a 
new instrument for measuring vapor tension, 
by Harold Moore,—Journal of the Society 
of Chemical Industry, 1920, page 78-T.) 


Physical Tests on Pyroxylin Lacquers 633 


of mercury. If the pressure of the atmosphere in a flask be 
lowered by means of a vacuum pump to 590 mm. of mercury, 
the liquid will boil at 90° C. 

There are two methods by which the vapor pressure of a 
liquid at a given temperature may be determined. 

1. The Statical Method. 

The vapor pressure of a liquid may be determined by intro- 
ducing a small quantity of the liquid into a closed barometer 


Vacuum or 
77 Sea ia 
PRESSURE. 


FIGURE 206 


One type of apparatus used to determine vapor 
pressure by the dynamical method. 


634 Physical Tests on Pyroxylin Lacquers 
et 
tube. (Fig 205.) The space above the mereury being a vac- 
uum, the liquid vaporizes at once. The height of mereury 
is then measured and the difference between this and the 
height of mereury in a barometer tube represents the vapor 
pressure of the liquid at the temperature of the experiment. 
Correction should be made for temperature expansion or con- 
traction of the mercury. 
2. The Dynamical Method. 


This method depends entirely upon the determination of the 
boiling points of a liquid at various pressures. (Fig. 206.) A 
flask is filled with the liquid to be tested, and a thermometer 
inserted. The flask is then attached to a reflux condenser 
which is in turn attached to a vacuum or pressure pump. ‘The 
vacuum or pressure is measured with a manometer gauge. 
The temperatures at which the liquid-boils are then plotted 
against the pressures recorded on the manometer gauge, 
after barometric corrections have been made. 

When dealing with the vapor pressures of mixtures of two 
liquids, three cases should be considered: (1) Two non-mis- 
cible liquids; (2) Two partially miscible mrs and (3) 
Two infinitely miscible liquids. 

To consider these more in detail. 

(1) Two non-miscible liquids. Regnault stated in 1898 
that the vapor pressure of two non-miscible liquids at a given 
temperature is equal to the sum of the vapor pressures of 
the two liquids at the same temperature. This rule holds 
for mixtures in all proportions, provided that there is an 
appreciable amount of either present. 

It may be reasoned from the above that the boiling point 
of two non-miscible liquids is that temperature at which the 
sum of the vapor pressures of the components is equal to the 
atmospheric pressure. For example: The atmospheric pres- 
sure is 760 mm. From the vapor pressure curves of ‘two 
liquids, it is found that at 80° C. the vapor pressure of one of 
the liquids is equal to 240 mm. and that of the other lquid 
is equal to 520 mm. 80° C, will then be the boiling point of 
the mixture at 760 mm. (The sum of 520 and 240). 

(2) Two partially miscible liquids. The vapor pressure 
of two partially miscible liquids is less than the sum of the 
vapor pressures of the two components, as was true in the 


Physical Tests on Pyroxylin Lacquers 635 


FIGURE 207 
Vapor pressure curves of several alcohols drawn from data in Physico-Chem ical Tables. 


500 


300 | 
Vapor Pressure, Millimeters of Mercury 


\ 

a 
Hina 

° 4 a be iy vT ap) 


eco, ‘sooubaq Rey 


lOO 


0 
0 
lO 
@) 


above Case 1, but greater than either of the vapor pressures 
taken singly. 

(3) Two infinitely miscible liquids. The vapor pressures 
of two infinitely miscible liquids is less than the sum of the 
vapor pressure of the two components and may be either 
greater or less than the vapor pressure of either component. 


636 Physical Tests on Pyroxylin Lacquers 


\ BEEBE” 
ANRC 
AEN LEN 


NMA MEAN 
HAEREUENETABNG: BB EEL || 
Oo 
[oP 


Been: ane » aetna 


1100 


Vapor Pressure, Millimeters of Mercury 


900 


300 


FIgurE 208 
Vapor pressure curves of several acetates drawn from data in Physico-Chemical Tables. 


This vapor pressure may be calculated in a large number of 


cases by use of the formula of Speyers: 


MPa + (100 — m) PB 


aes 100 


Physical Tests on Pyroxylin Lacquers 637 


RE es RRR PS RSS SS A SESE RTS SP STR TE SSS RE TEE ETL | 


where P is the vapor pressure of a mixture of two completely 
miscible liquids at a given temperature. 

Pa and Pp are the vapor pressures of the two components 
at the same temperature. 


M is the molecular percentage of liquid A. 


There is given below vapor pressure curves of a number 
of liquids used as lacquer solvents. ‘These curves were drawn 
by the writer from a study of the data on pure materials 
as appearing in Physico-Chemical Tables.—J. C. Evans— 
Published by C. Griffin and Co., London—1902. Pages 451- 
525. Another book giving much data on vapor pressure 1s 
that by Sydney Young—Distillation Principles and Processes. 
—Maemillan and Co.—1922. 


Testing the Speed of Evaporation of Solvents from Lac- 
quers. On pages 474-5 are given the results of a study of the 
speed of evaporation of thinners from paint and varnish films 
of the oleo-resinous type. There is presented below a some- 
what similar study of the speed of evaporation of thinners 
used in pyroxylin lacquer coatings. The relatively great 
speed with which the latter solvents or thinners vaporize, 
as compared to those used in oleo-resinous varnishes has 
made the study a difficult one. It is felt, however, that the 
results obtained will be of considerable aid in the design of 
the new type coatings. Experimenters so far have paid but 
little attention to one very important factor in lacquer coat- 
ings, and that is the condition in which the solid constituents 
emerge from solution to form films. The character of films 
and their ultimate durability will depend very largely upon 
this factor. When pyroxylin emerges from a very rapidly 
evaporating solvent, the dew point of the moisture in the 
atmosphere may be reached and cause premature precipita- 
tion of the pyroxylin, producing an effect known as ‘‘blush- 
ing.’’ Even if opaqueness of film is not shown, the continuity 
of the surface is disturbed, and ridges of pyroxylin may be 
seen with the aid of a hand glass or low power microscope. 
Similarly, very rapid evaporation may cause ‘‘pin-holing,’’ 
‘‘ooose-fleshing,’’? ‘‘orange peel’’ effects, and similar dis- 
turbed conditions of film that detract from the appearance 
and physical character of the finish. A rapidly evaporating 
solvent may be mixed with a slower one, and, thus help to 


638 Physical Tests on Pyroxylin Lacquers 


eels | | 
"nance SEE PL TIES Geewees post 


| ectene 
|| | 


180° 


Br {8 


160° 


Lag 


I20° 


ic 
N 
IN 


S) 
o 
° 


ees 


Degrees Centigrade 
° 


SX | 
SY} 
cere 
HH 
a 
a 
5 
oS 
ce 


as 

Fe 
e 
a 


Ny 
ss 
q 


ty 


10 20 30 40 50 60) 170) GO™seGn ee 
Percent Distilled 


Figure 209 


Distillation ranges of various solvents used. 


overcome this trouble, but the safer method would seem to 
he in the use of solvents whose evaporation curve would tend 
to follow a straight line, and which at all times will act as 
solvents for the cotton. 


When a mixed solvent is used, made with a rapid evaporat- 
ing true solvent and a substantial amount of a non-solvent 
such as a coal tar hydrocarbon, the pyroxylin will remain in 
solution only so long as an influencing amount of the true 
solvent is present in the film. Later, and before dryness is 
reached, if the non-solvent should be present in maximum 
concentration, it may exert its non-solvent properties and 


Physical Tests on Pyroxylin Lacquers 


UN 
NE 
PREC 
CCC 
NS 
WRN ET 
SINGER 
WE WG a 
SANG: 
See C eae 


S07. 90 100 


Time in Minutes 


Pre Vr 


2 
O 
ie) 
e) 
ike) 
oO 
“wt 
oO 
40) 
O 
N 
Hy O 
Oo ) .e) 
a oS OR Gee inenee ari) 2 
jUBIoAA Ul SSO7 jUadUeq 


10 
. Determined in small friction top can covers. 


FIGURE 2 


solvents used alone 


639 


640 Physical Tests on Pyroxylin Lacquers 


throw the pyroxylin out of solution in a clotted form. This 
illustrates the necessity of having present a sufficient amount 
of true solvent at all times during the evaporation period to 
keep the pyroxlin in true solution until films of apparent 
dryness are produced. 

Although pyroxylin films are said to dry in a few minutes’ 
time, real complete evaporation does not take place over a 
very long period of time, as the gel-like film acts as a sponge 


to hold small amounts of solvent that go out slowly. This is” 


illustrated by placing an article that has been lacquered for 
even several days, in a warm box, when the odor of escaping 
solvent will be noticed. This result would also indicate the 
advisability of baking lacquers when dryness of film is an 
important consideration to prevent surface defects of subse- 
quently applhed coatings. 7 


Rules Governing Evaporation.—There is a tendency on the 
part of all liquids to vaporize to a greater or less extent. The 
degree depends on conditions of temperature and external 
pressure. The molecules in a liquid are constantly in motion, 
vibrating back and forth. By a number of progressive vibra- 
tions a molecule may be propelled with sufficient force and in 
the proper direction to carry it into the atmosphere above the 
liquid. It has then passed into the vapor state. When a 
number of molecules vaporize, the liquid loses weight and is 
said to be evaporating. 


If, however, the liquid is in a closed container, the space 
above the liquid will fill with vapor molecules. These are 
also vibrating rapidly and in their motion will strike the sur- 
face of the liquid to which on striking they will be attracted, 
becoming a part of the liquid itself. 


Consequently a liquid will evaporate in a closed space until ~ 


the atmosphere above it is saturated with the vapor of the 


liquid. At this point an equilibrium is set up where an equal — 
number of molecules are passing into the liquid state to those — 


passing out. Loss in weight ceases at this point until some 
of the vapor is drawn off. A change in temperature alters 


the speed of the molecules, either increasing or decreasing — 


the evaporation. 


From the above might be drawn four conclusions which gov- 
ern the speed of evaporation of volatile liquids: 


Physical Tests on Pyroxylin Lacquers 


a 


lO 


Keye) 


Time in Minutes 


| 
an Gc CR GO8m) 
I 
\ELGRGE 

RNA 


FIGURE 211 


641 


Evaporation of mixtures of two solvents determined in small friction top cans, 


642 Physical Tests on Pyroxylin Lacquers 
1. Temperature. An increase in temperature accelerates 
the evaporation by increasing the vapor pressure. F 
9. The quantity of the vapor rising from the liquid in the ~ 
surrounding atmosphere. No evaporation could take place — 
in an atmosphere saturated with the vapor of the liquid, and — 
vaporization would reach a maximum in an atmosphere abso- ~ 
lutely freed of the vapor. | 
3. The rapidity with which the atmosphere is renewed. 
4. The extent of surface presented to evaporation. 


When nitrocellulose is mixed with the various solvents 
used in the industry no chemical reaction takes place. 


Evaporation of One Solvent—The more common volatile 
solvents, used in the lacquer industry, were obtained for the . 
purpose of determining as accurately as possible the differ- 
ences between them, from the standpoint of speed of evapora- — 
tion. Those chosen were Ethyl, Butyl, and Amyl Acetates, ~ 
Diethyl Carbonate, Specially Denatured Alcohol (Anhydrous, — 
Formula No. 6), Butyl Alcohol, Fusel Oil, Solvent Naphtha, . 
Benzol, Toluol, and Furfural. 


The solvents used were all commercial grades and were not — 
redistilled to obtain specially constant boiling ranges. Dis-— 
tillation ranges were determined for all these solvents using — 
the method outlined in the Federal Specifications for Turpen- — 
tine. The thermometer used was a distillation thermometer 
with a range from 0° C. to 490° C. The results are shown 
in Fig. 209. 

A number of methods to determine the speed of evaporation 
were at first experimented with, but none of them gave the ~ 
same relative results for repeat determinations. This was — 
largely due to variations in temperature and in the movement 
of air in the laboratory. The first attempts were made on ~ 
relatively large quantities of the solvents, each being run at — 
a different time, and none of the samples allowed to go to dry- — 
ness. A shallow pan was filled with the solvent and weighed ~ 
at intervals and the evaporation plotted together with the — 
time. It was proven at once that this method was inaccurate, 
as two samples of the same material run one immediately 
after the other failed to give concordant results. - 

It was thought that the atmosphere above the pan became > 
more or less saturated with the vapor of the liquid, thus alter-— 
ing the vaporization. Accordingly a stream of air was passed 


Physical Tests on Pyroxylin Lacquers 


20 30 40 50 60 7 80 90 


lO 


One @) 
Oy wee ae 


yUBIan Ul SSO] YUddUE4q 


Time in Minutes 


FIGURE 212 


Evaporation of solvents from 16 oz. nitrocellulose solutions. 


643 


Determined in small friction top can covers. 


644 Physical Tests on Pyroxylin Lacquers 


about two inches above the surface of the pan. It was found 
that by varying this air stream the results could be made to 
vary within very wide limits. Concordant results were not 
obtained with this method. ; 

The method finally decided upon made no allowances for 
either temperature or movement of air in the room. One 


gram (+.005) of the solvent was weighed from a burette into 2 


a friction top can cover (diameter 5 em.), the material being 
flowed over the bottom and the time noted. The sample was 
then reweighed at intervals until it had completely vaporized. 
All the samples were run under exactly the same conditions 
and at the same time. The results obtained are shown in Fig. 


210. Tf these same solvents were run in the same manner at © 
another time different results would be obtained, but the — 


curves would maintain their same relative positions with re- 
spect to each other. This was determined by actual test. 

It will be noticed that all the lines on the chart are nearly 
straight, which probably indicates the purity of the solvents 


and their freedom from slow vaporizing residues. As will — 


be seen in Fig. 211, which represents mixtures of two solvents, 


the curves are not straight lines except in the cases of the pure ~ 


solvents themselves. 


Evaporation of Mixtures of Two Solvents——Two solvents © 


were chosen, one evaporating very rapidly and the other very 
slowly. Various proportions were made by volume. 


1s Se ee ee 100% Ethyl Acetate 
9 75% Ethyl Acetate 
Ss OE he a 95% Butyl Alcohol 
3 50% Ethyl Acetate 
ei ES a eee 50% Butyl Alcohel 
4 25% Ethyl Acetate 
Re ee hi 75% Butyl Alcohol 
Boo ey Oo ee 100% Butyl Alcohol 


These five samples were run in exactly the same manner as — 
the pure solvents used above. The results of another test on — 
the same samples would show the same relative positions of — 


the curves and their general direction will be the same. The 
results are shown in Fig. 211. 


7 ¢ 
2 anh: ee : P 
ee pen SS Nee v . 


Physical Tests on Pyroxylin Lacquers 645 


Determined in small 


Ke) 


QD as 
es 
OWL 
ON 
JONG fF 


ie 
ee 


~—y.)§.].|, SRS 
{Seas 
O Oo © Ox = 
Pee Oo in fe 


Oo O 
ae we 


lO 20 30 40 50 60 70 80 90 100 


aporation of Butyl Acetate from solutions of various percentages of nitrocellulose. 


Ey 


yyBbiayy ul SSO7 YUaddaY 


646 Physical Tests on Pyroxylin Lacquers 


As will be noticed the curves for pure ethyl acetate and 
pure butyl alcohol are very nearly straight lines, while those 
of the mixtures are bent, showing very clearly the presence 
of two or more liquids which vaporize at different speeds. In 
each case the mixture loses a large proportion of its ethyl ace- 
tate, then loses a mixture of the two solvents at a medium rate 
of vaporization and finally loses the butyl alcohol at practi- 
cally the same speed as butyl alcohol vaporizes alone. 

The mixture of 75% Ethyl Acetate and 25% Butyl Alcohol 
for example, apparently loses about 45% of the 75% LHthyl 
Acetate present. The remaining 35% apparently evaporates 
with probably about 10% of the Butyl Alcohol. This leaves 
about 15% Butyl Alcohol to vaporize practically by itself as 
the curve from that point corresponds very closely to that of 
Butyl Alcohol. 

The distillation range was determined for the mixture of 
75% Ethyl Acetate and 25% Butyl Alcohol, and is shown in — 
Fig. 209, together with the distillation ranges of the various © 
solvents used. , 


Various Solvents Mixed With Nitrocellulose-—Solutions 
were made up on the basis of 16 ounces of dry nitrocellulose 
in one gallon of solvent.* No allowance was made for ‘‘swell- 
ing.’? The solvents used were Ethyl, Butyl and Amyl Ace-— 
tates, Diethyl Carbonate, Furfural and specially Denatured 
Aleohol (Alcohol Soluble Nitrocellulose was used in this last 
ease while regular solvent nitrocellulose was used in all other 
solutions). The remainder of the solvents, for which the — 
speed of evaporation was determined above, were not used 
in these experiments as nitrocellulose is but sparingly soluble — 
in them. 3 


Several methods to determine the speed of evaporation — 


were tried before satisfactory results were obtained. In this 
work weighing bottles fitted with corks in which a brush was : 
fastened were first used. The bottle was weighed, a sample 
transferred with the brush to a thin glass plate and the bottle ~ 
reweighed to determine the weight of sample taken. The glass — 
plate on which the sample was brushed was weighed at varl- 
ous intervals, timed by a stop watch, until a constant weight — 
was obtained, indicating that all the volatile matter had evap- — 


*The nitrocellulose used in these tests was received wet down with 30% z 


alcohol. In other words, 100 lbs. of the material contained 30 Ibs. of alcohol. : 


Physical Tests on Pyroxylin Lacquers 647 


orated. Concordant results were not obtained with this meth- 
od due to the fact that a constant thickness of film could not 
be obtained, approximately the same weight of film being 
spread in a different thickness each time, presenting a vary- 
ing surface to evaporation. 


The method finally decided upon was the one used in the 
work on solvents alone as described before on page 644. 
One gram (=+.005) was weighed from a burette into a small 
friction top can cover, (diameter 5 cm.) and the sample spread 
equally over the surface. The pan was reweighed at intervals 
until a constant weight was obtained indicating that all the 
volatile matter had evaporated. The results obtained are 
shown in Fig. 212. These curves are thought to be compara- 
tive, but should not be compared with curves which are shown 
in other plates in this chapter. 


Various Quantities of Nitrocellulose to-One Solvent.—Five 
solutions were made up by adding 1, 3, 5, 7, and 9 grams of 
nitrocellulose to 25 cc. of Butyl Acetate. These solutions rep- 
resent 3.74, 11.23, 18.70, 25.18, and 33.66 ounces of dry nitro- 
cellulose to one gallon solvent, respectively. The solutions 
were run in the same manner as before; that is, weighing one 
gram from a burette and allowing it to evaporate, weighing 
at intervals until dry. The results are shown in Fig. 213. 


It will be noticed from the chart that in each case approxi- 
mately 50% of the sample evaporates before the lines diverge 
at all. At this point they spread fan shape and each goes to 
a point which is determined by the particular percentage of 
non-volatile present in the sample. 


After the solvent had evaporated, the average thickness of 
the film was determined. The results obtained as compared 
to the thickness of Oil Varnish films made from varnishes of 
different volatile content is shown below: 


Grams Ounces 

wet Nitro- dry Nitro- Thickness 

cellulose cellulose of Lacquer Viscosity (Gardner-Holdt) 

in 25 c.C. to 1 gal. Films 
mn 3.74 20u Two bubbles faster than A 
3 1t:23 32u One bubble faster than A 
5 18.70 5d B 
‘< 25.18 60u G 
9 33.66 TT K 


648 


Non-volatile 
40% .. 
45%... 
50% .. 
55% .. 
60% .. 


Thickness of Varnish Films ie DE Bohai 
Viscosity Constant K (Gardner-Holdt) 2.75 Poises — ss 


- 


“ 


Physical Tests on Pyroxylin Lacquers 


ae 


CHAPTER XXXVII 
MISCELLANEOUS METHODS OF TESTING MATERIALS 


There are presented below some miscellaneous methods of 
test which have been developed at this laboratory and which 
have proved of general use in evaluating raw materials or for 
studying their properties: 

Testing the Color Number of Dry Pigments.—On examin- 
ing samples of prepared paints that have been stored for long 


FIGURE 214 


Water solution of methylene blue added to lithopone in bottle on left and to 
china clay in bottle on right. After shaking and standing the china clay has 
completely absorbed the blue color, producing a blue lake pigment which 
subsides to the bottom and leaves the colorless water above, the lithopone has 
shown but little absorption and is still white. 


periods of time, the oil floating on the surface will often 
appear to be extremely pale in color as compared to the rather 
dark amber color of the raw linseed oil used in grinding. 


650 Miscellaneous Chemical Tests 


Apparently the foots and some of the coloring matter in the 
oil are adsorbed by the pigment particles, thus allowing the 
oil to become very clear and of unusually light color. As a 
result of such observations, the writer has assumed that pig- 
ments will show varying degrees of adsorptivity. In order to 
determine the possibilities in this direction, a few dyestuffs 
were experimented with. In dilute aqueous solution, they 
were shaken with a number of pigments. Almost immediate 
discoloration of these dye solutions was observed when in 
contact with some pigments, and practically no change with 
others. The results seemed so interesting that it was thought 
advisable to develop a quantitive method of determining the 
adsorptive properties of various pigments, and for this pur- 
pose there was selected a dyestuff which could be titrated 
quatitatively, namely Methylene Blue O concentrated. While 
it is possible that Indigotine and some other dyestuffs might 
be fully as useful in this connection, it was decided to use the 
methylene blue because of the very sharp changes in color 
value, which are observed upon titration. The method of 
running the test is as follows: | 


Method of Test—Twenty grams of dry pigment is placed 
in a half-pint clear glass bottle, and 150 ec. of a standard 
aqueous dye solution is added. (This dye solution is made by 
dissolving 0.25 grams of Methylene Blue in one liter of dis- 
tilled water.) The bottles containing the pigment and dye 
solution are then capped and vigorously shaken for two — 
minutes every day for a period of one week. They are then 
allowed to stand for any desired period of time, and the dye 
content of the solutions determined by titrating an aliquot 
portion of 50 ce. of the clear liquid with a 0.01N solution of 
titanous chloride. The difference between a blank titration 
on a portion of the standard dye solution and the pigment 
sample titration, multiplied by the grams of dyestuff which 
each cubic centimeter of titanous chloride is equivalent to, 
gives the amount of dye adsorbed by the pigment. This factor 
might be termed the Color Number, and is expressed as the 
milligrams of dye adsorbed per gram of pigment. 


Preparation of Solution—The method for the preparation 
of the 0.01N titanous chloride solution is similar to that used 


Miscellaneous Chemical Tests 651 


by English * for estimating the strength of dyestuffs, and is 
as follows: Titanous chloride usually comes upon the market 
in a 20 per cent aqueous solution; 33.5 ce. of this solution and 
70 ee. of concentrated Bdrochloric acid (specific gravity 1.19) 
are boiled together for about a minute. After cooling in an 
atmosphere of carbon dioxide or hydrogen, this solution is 
added to 5 liters of distilled water in a large bottle. This dis- 
tilled water must be free from dissolved oxygen, and should 
first be boiled 20 or 30 minutes and cooled in an atmosphere 
of carbon dioxide or hydrogen before placing in the bottle. 
After the titanous chloride acid solution is added to the dis- 
tilled water, thorough mixing is obtained by passing a rapid 
stream of ehon dioxide or hydrogen through the solution. 


Titration.—This titanous chloride solution is used in the 
following manner: Fifty ce. of clear dye solution is removed 
from above the settled pigment in the bottle, filtered if neces- 
sary, and transferred with a pipette to an Erlenmeyer flask. 
Twenty-five ce. of a 25 per cent aqueous solution (75 water, 
95 sodium tartrate) of sodium tartrate is added. The mixture 
is boiled for three minutes, and titrated while hot with the 
titanous chloride solution, in an atmosphere of carbon dioxide, 
to the last distinct color change. 


Lakes Formed.—With certain pigments, the rapidity of 
adsorption in the above test was so great that within a few 
minutes after the addition of the Rega solution and shaking, 
the color was entirely discharged by adsorption, and several 
subsequent additions of the dyestuff solution were necessary in 
order to show any permanent color. With such pigments, the 
plan of procedure was to reduce the amount of pigment used 
for test, using 10 grams, 5 grams, 1 gram, or lower quantities, 
with the same amount, namely, 150 ce. of the standard color 
‘solution. It was interesting in these experiments to note the 
lakes that were formed with various pigments. Thus, for 
instance, certain white pigments were practically unattacked 
by the solution of blue dyestuff, and settled out to the bottom 
of the bottle to a white mass, with the clear methylene blue 
solution above. Other white pigments rapidly adsorbed the 
dyestuff and settled out to the bottom of the bottle in the form 
of a blue mass, leaving colorless water above. 


*Analysis of Aromatic Nitro-Compounds. F. L. English, J. Ind. Eng. 
Chem., Oct., 1920, p. 994. 


652 Miscellaneous Chemical Tests 


In order to determine whether there is any relation between 
color adsorption and oil adsorption, the pigments which were 


included in the tests were run for the latter physical property 


and a summary of the results is given below. In the Chart 
the color number is the milligrams of dry methylene blue dye- 
stuff adsorbed by 1 gram of pigment. The acid number is the 
milligrams of sulphuric acid per gram of pigment. The alkali 
number is the milligrams of potassium hydroxide per gram 
of pigment. The oil absorption is the grams of oil required 
per 100 grams of pigment. This was deterinmed by rubbing 
the pigment on a ground glass plate with a spatula, adding the 
oil drop by drop until the pigment assumed a coherent state 
and slightly smeared the glass. 

In running the acidity or alkalinity, tenth normal solutions 
of sulphuric acid or caustic potash were used with all pigments 
except with Nos. 1 to 10. With these pigments, a fiftieth nor- 
mal alkali or acid solution was used, but unfortunately only 
ten grams of each pigment were left from the reserve stock 
for these tests, and therefore the information presented in 
our Chart does not entirely agree with the acid number given 
by the manufacturers of these pigments who generally use 50 
grams of pigment for determining alkalinity or acidity. The 
information submitted by the manufacturers was to the effect 
that samples Nos. 2, 4, 7 and 10 are aproximately neutral; 
samples Nos. 1, 5, 8 and 9 are slightly alkaline; while samples 
Nos. 3 and 6 are more strongly alkaline. 


TABLE 72 


Color Number of Pigments 


Color Acid Alkali Oul 
No. Pigment Nos. Noroe he Absorption 

1 No. 1 Lithopone iba ee 1.09 Neutral 9.9 

2 No, 2 Lithopone......tuinee a eee 0.70 Neutral 10.2 

3. No. 3 Lithopontic oan 0.81 0.23 tha 

4 No, 4 Lithopone. 7.20 2. hie ee 0.682 0 11.9 
Slight 

5. No. 5 Lithopone....c aie ee 0.99 Alkaline 13.6 
; Slight 

6G) No. 6 Lithoponé. 71-0 ee 0.47 Alkaline 14.9 

7 No.7 Lathoponés, 4 2 ee 0.89 Neutral is.7 

& No. 8 Lithopote nis 7o ee ee i Neutral 16.2 


9 «No. 9 Lathopone \Auyi cous ee eee 1.04 Neutral ioe 
10° Noo 40 Lithopone:c3 eee ae eee iS Neutral 17.8 
11. Biano Fixe 3s y50.. eee ee oe 0.68 0.04 24.5 
12 - Agbestine.vGgewjcis ee Ree ee ee 18.6 0.04 35.0 


a 
ei 
524 
ee 

ye 

ee 


Miscellaneous Chemical Tests 653 


Color Acid Alka Oil 
No. Pigment No. No. No. Absorption 


MRE GOVY HIELO sie ccts sarc caecsccccdsccesctsvcssecesceccn on 3.43 — 19.5 
Serer ea ons sin ve sci acasafscgeredizcasisanens 12-5 0.04 50;5 
RICE CAV SUIT 6... seco ces gececsdgusanecsesnnee 0.94 ———— a es 
16 Leaded Zinc (5% Lead sulphate).....0.000000....... 125 —__—_— 1955 
1h, A obec dun sao cess sees cgauersistececsyes 13.8 0.95 32.0 
UE ATION il one ce cd ccscacseivldecccegeseecco ses P2324 0.06 3tt3 
MEUPITIETE LAT ATIOK io ices ocescecccevcessectclicersecsscenreeee 0.70 —_—_—_—— 18.7 
Nooo ce gacccac cose sesensdosscstanpaseacedessnens 0555) <0, 12 | 16.8 
eee re 1 Peat OXI 2... <.<cccsecsessccccceeescceeceees 1.85 ——__—_— 56.9 
22 Leaded Zinc (65% Lead Sulphate)................ £28 0:13 1321 
meee yy nite Lead (Electrolytic)...............ccccceccsecseeees 0.47 0.06 11.8 
24 Medium Chrome Green 16% on Barytes- 

i ONES on 6.96 pe 14.9 
25 Light Acetate Green on Barytes Base.......... 1.82 ———— 10.2 
26 Light Grinding Green. 25% on Barytes- 

EAS aay feck io Lvs ectresasnes: Mine Beto 3.69 —__—_—— 15.9 
27 Chrome Green. 20% on Silica Base............ Nar —_———— 17.8 
soon lst O54 Tack G0 Seale 1.82 ——— —— 
eames yr eritie, F. ML coc ccce se secsscseccsccseseeeeeecees 37.2 0.06 — 
UG PC TOLCCT C}CHLE. .... ci cccccesc-ceceecsssesccveeseoceses 3.62 —_— 1S 
TS eT 0 Sl Os a 0.00 ———— 39.5 
62 italian Raw Sienna. 54% Iron Oxide.......... 34.3 —_———— 48.5 
Go Herrite Yellow. Dark Orange..............0..00.... O70 — 0.54 61.0 
eae, Lemon Chrome Yellow......................... O50! 0:12 16.8 
SVS Coho) St 7 rr Lice —_— 49.0 
36 Turkey Raw Umber. 46% Iron Oxide........ 375 — 49.5 
37  Prince’s Mineral. 34% Iron Oxide.............. Lt Se 24.0 
38 P. Metallic Brown. 61% Iron Oxide............ 1.22 ———— 34.0 
yh os Lassies vesvucSsainsesevseseonnes 0.67 0.11 10.7 
eer erurore Oxide, 82% Iron Oxide................4: 1.38 ———— 10.2 
41 No. 59 Indian Red L. N. 96% Iron Oxide 0.23 ee 20.1 
42 No. 50 Canadian Oxide. 91.5% Iron Oxide.. 1.83 eee 28.5 
43 Maroon, 10% Alphanaphthylamine on 

Barytes-W hiting Base: ..........0.....ccccccseers —_— 23:8 
44 Alizarine Lake................. Tg SP aa erga 33.6 — 
45 No. 3439 Tuscan Red L. N. 26% Iron 

ye ays  iahincs's Sadie uiapeonedene oie 3.70 16.8 
46 American Vermilion. Basic Chromate of 

Ne hy i cnieisevsushatucd thacsguaaca 0.28  ————— 131 
47 Deep Para Red—10% Para on Barytes- 

TEs en a oe — 18.7 
48 Deep Para Red—20% Para on Barytes- 

Ee 13.4 a 40.5 
MM OES OC oie ccsaseies sesessceeccesssnsstscesseensvicesens 1.88 0.11 14.6 
Boeeeen English Vermilion........0..)..... seca 0.76 ——— 12.9 


51 Light Para Red—10% Para on Barytes- 


USE Sa a 1.88 O14 18.7 
52 Scarlet Lake—34% Xylidine on Blanc 
RE gehen Sea cag urtats oj-abig ue A nee —_ a5 


53 Methyl Red. 2% Lithol on Orange Mineral ly Ae) 0.04 10.7 


654 Miscellaneous Chemical Tests 
a ——————— 


Color Acid Alkali Ol 


No. Pigment No. No. No. Absorption 
54 Orange Minerali.n.v.cieniiagn tomers 0.79 ——— 134 
55. Cherry Red icc. 3: atone ses ea eee 3A 8.2 
56 C.P Orange Chrome Yellow... 24. 1.08 0.09 17.8 
57 Magnetic Red Oxide. Prectpitated.............. 1.36 0.24 33:5 
SR Prussian Blue. ioc. et ae ones ae 1.80 0.66 100.5 
590 Drop Black Xo Roe nnce oe ei ee 36.9 0.76 49.5 
60 No. 73 Drop Black cc rece oe eee 36.6 — 1329 
61 Mexican Graphite. 52% Carbon................. 18.0 0.06 36.0 
62 B. V.; Lampolack.....0 os cnbgpuneme eee 14.7 0.12 — 
63. Carbon Blacit snc Gc. eee 69.6 0.06 46.0 
64... Carbon Blacks (180). ..2c coger 187.5 ———— 186.6 
65 Black Iron Oxide. Precipitated.................-.: L083 49.5 
66 Red Oxide of Mercury...2 2 0.97. . 048 8.8 
67 Antimony Oxide.:..03.5. ieee eee 0.36.2 26.5 
68 Fuller’s Barth. ..c.s55¢-4e-.0 ogee 294.0 ——_——— 108.4 
69 Lithopone S1926..........0. cece tes 102 32.0 
70. Zine Oxide XX 51926005 ec ee — 0.66 29.0 
71 Zine Sulphide-S1926.5o.5 cc har ee 1.525236 21:5 
72 High Strength Lithopone $1926..............04 2.17 ——— 16.8 | 


Under Acidity a long dash is shown wherever pigments required only one drop of 
N/10 Alkali to show permanent red color with Phenolphthalein. 


Testing the Wetting Properties of Pigments With Different 


Liquids.—A considerable amount of work has been done in 


this laboratory in determining the wetting properties of vari- 
ous liquids upon pigments.* In this work, large test tubes 
were used, into which were placed 10 ec. of each of two differ- 
ent types of immiscible liquids. 

Into each test tube was then placed an amount of dry pig- 
ment equivalent to the size of the head of a match stick. As 
the pigment dropped through the upper layer of liquid, its 
speed decreased when it reached the line separating the two 
liquids. In many instances reactions would occur at that line, 
which would subsequently allow the pigment to either drop 
through to the bottom liquid or remain suspended at the inter- 
face. Upon shaking the tubes for a few seconds, an emulsion- 
like mass would be formed, which would gradually separate 
into two layers. The pigment would either go into one layer 
or would be suspended at the interface. Very rapid move- 
ment of the temporary emulsified particles would take place 
for several seconds, a miniature battle being waged between 
the liquids to determine which would wet the solid. That the 


*See Scien. Sec. Circ. No. 295. 


Miscellaneous Chemical Tests 655 


result of the battle would not be due entirely to the gravity 
of the materials is indicated by the fact that pigments of prac- 
tically the same gravity might be found to finally rest at the 
bottom of the lower liquid or in the upper liquid, according to 
the surface attractions presented. After these experiments 
were made, it was found that some similar work was done by 
Hoffmann with a number of dry substances but with liquids 
that are applied less to the paint and varnish industry than 
those experimented with in the present writer’s work. Hoff- 
mann’s experiments are described on page 102 of Bancroft’s 
‘Applied Colloid Chemistry.’’ He found, for instance, that if 
powdered glass is treated with water and then shaken with 
kerosene, the glass goes into the water phase. If, however, 
the dry glass powder is first allowed to stand for a long time 
with kerosene, some of the glass powder will remain in the 
interface, but vigorous shaking will cause the water to dis- 
place the kerosene. 


Some of the results obtained are pictured and reported 
below. 


It is conceivable that processes might be developed, where- 
by pulp colors coming from the washing tanks, and probably 
relatively free from adsorbed air particles, might be wetted 
with much greater ease than dry particles, the surface of 
which had absorbed air or gases and which would then 
be resistant to wetting with oil. Such pulp colors, if 
properly agitated with oil under certain conditions, 
possibly in the presence of added chemicals * to lower the 
surface tension effects, might readily be incorporated with 
the oil. Experiments in this direction apparently offer prom- 
ise. The fineness of the pigment, the amount used, and the 
acid value and temperature of the liquids are factors which 
would probably exert influences in such phenomena. 


PIGMENTS ADDED TO TUBES CONTAINING TOLUOL 
AND WATER 


Upon adding pigments, all settled gradually in snowflake fashion to the 
bottom of the tubes, with the exception of Nos. 10, 14, 15, 16, 17, and 18, 
which remained at the interface. After shaking, the pigments remained 
Suspended in the layers indicated by X. 


*Aqueous soap solutions are suggested. 


656 Miscellaneous Chemical Tests 


Upper Layer Lower Layer 


Toluol Water 
1 Antimony Oxides. 0327) ee xX 
9° “Zane Oxide So tae xX 
3% LAtBODOREG Gd... nd te yeh xX 
4 Leaded Zinc (5% Lead)...:....0.... >, 
5. Basie Lead Sulfate co xX 
6 Basic Lead Carbonate. ..20..00% 4 
i. Baran Trane Sos = 
By Calerwnr Pitan rt eee xX 
Rar Pere: Lao. oh eaee ree ake »4 
10. Magnesium iSil-cate.7. a x 
t1°) Calsidiy Carbonate.3 244.2 x 
12 + ‘Red -Lead 2 ae ae x 
13.“ adien Reda on ee eae ».4 
14°: Toluidine Toners. Gaieceee ».4 
15. Raw Sienties...< oii eee xX 
16. “Raw Umber4-2550 eae Some at interface xX 
17 Graphite ck 2 2 ee At interface 
18. -- Carbon Blacks Us ce eee x 
19. “Fuller's Barth: hoa eee “6 
20 Light Green 25% on Barytes- 
Clay -Baseccae ie ee Some at interface xX 


PIGMENTS ADDED TO TUBES CONTAINING A MIXTURE OF 
MINERAL SPIRITS AND WATER 
Upon adding pigments, the general tendency was for them to remain 
largely at the interface, with slight amounts settling slowly in snowflake 
form to the bottom. Pigments Nos. 2, 5, 11, 14, 16, 17, and 18 remained 
entirely at the interface. Upon shaking, the pigment remained suspended 
in the layer indicated by X. 


Upper Layer Lower Layer 
Mineral Spirits Water 
1 > Antimony Oxides47.4 5 ies xX 
2, dine Uxede. 3.7.93. 70h Se ere x 
3 “Lathopone. with. cpaaeeerer ear uee xX 
4 Leaded Zinc (5% Lead)............ At interface 
5.” Baste bead: Sultatex. ie sacseeee At interface 
6 Basic Lead Carbonate. » 
7 Barium tangs) eee At interface 
8. Calerum Titesiox piesa xX 
9 -- Pigre Pie. 0n cv ie eee xX 
10 Magnesium Sulitate. nos ces. xX 
11 .. Calcium Carbonate nie ee = 
12° Red Dead Ae se eee x 
13 “Indian Regist oe ee At interface 
14 » Toluitine: Toner. 3 3 ee At interface 
15: Raw Sienna oe eer x 
16 Raw Umber 25.450 4 
17: Graptite o223e.. 2 ele xX 
18 = Carbon Blick .cnae i ee At interface 
19° Puller’s Earth... iota At interface 


20 Light Green 25% on Barytes- 
Clay Base: 25.2 ie ee At interface 


Miscellaneous Chemical Tests ) 657 


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m3 

a 

ae 
nS 

as 

¥. 

a i, 

DAE. 

: 3 
a. iY ca ak 


283° 
Cle 
oa ¢ 
put 
Oak 
5 
24 
ca 
= 
pos 
¢€ 
Ones 
So 
¢et 
a 
ae) 
eG) 
2 Ad OR) 
San) 


Ge 


232 #8 
3 a xX 
Cod” nen 5 
417 5: 
— PO 
Seni > 
Det 
© 3 
o = 
ote 8 
rho npriace 

sya 

2 

» tag Mins 
ge 9 
A) Uk 

: a a 
Shes x 


. \ ° 
S 
: bay 
is 


Fig. 215 : Fig. 216 


Fig. 215.—Before Shaking: Upper layer toluol, lower layer water. Lithopone 
pigment rests at interface and is gradually dropping like snow- 
flakes into lower layer. 


Fig. 216.—Before Shaking: Upper layer linseed oil, lower layer water. Litho- 
pone pigment dropped rapidly in spherical shape to bottom layer and carried 
with it a globule of linseed oil which is endeavoring to become detached and 
float back to surface. A bubble of air is occluded at the apex of the oil. 


PIGMENTS ADDED TO TUBES CONTAINING WATER AND 
LINSEED OIL LAYERS 


Upon adding pigments, they suspended to some extent throughout the 
upper oil layer, then gradually started to diffuse through the lower water 
layer. Pigments 13, 15, and 18 remained in the upper oil layer for a very 
Substantial period of time before diffusing slowly into the latter layer. Upon 
Shaking, the pigment remained suspended in the layer indicated by X. 


Se ee a ee eee Te 


Upper Layer Lower Layer 
Linseed Oil Water 
Meeemony Oxide........................ Xx 
MUG Xx 
MP EMODONG. oc... secs Very cloudy Xx 
4 Leaded Zinc (5% Lead)............ x 
maeeeaic Lead Sulfate.................... Xx 


¥ 


White _ 
spherical shape 
king the oil — 


5 3B [a 
> Pe |r 
Seu = g 
NL e &le& 
x S ibd] bpS| bo] [PS [PM [Pd P< |X 
SE Ret 0 8 a> 
aS %o}/ad 
3 oe] ge 
= iy BS 
a |p N 
2 \ 
YN SS 
B 
— 
Ww é 
oy —_— 
=> 
Bi scl kh & IX 
roby Nes 
an - © 
O] as 
= 
By Be 
2) <0 ome a ei aaa ea) ei Camieen laa 
ov Be OS ae he ad 
q et ae ied en rr 
W af toa lea petite 
— cal : “2 BSI Wares Ben Lad an 
"Oo med tiie bam ies ee a een 
5 ee alee sais 
rh eae eeaeg oee ae dac, athe 
P A : = ae a 
Ss mie. Lor be Sle alts 
@| 2 q ap ey ah re ; rt (a 
O18 8 3 SAN aon aed tare eo: 
ole Ic as) Pad acd oe 
g ge |=lalelsi*\s 
1S K| oO Y | 
Hobo oi Sha] Sie 
“a)5 o o | &~|'O 1B 
Ale = Hl) aia |Clola 
B}] a ae) Bia | 8} 9) 4a] 
09 jaa ee) O MiSs lOiM hale 
Ww © |t [oe] DIC Is In [oO | 
© Sie ie isi 


FIGURE 218 


FIGURE 217 


Fig. 217.— Before Shaking : 


aves a series of milky threads caused 


yer linseed oil, lower layer water. 
It then drops rapidly in a 


toward the surface. 
Upper layer alcohol, lower layer linseed oil. White — 


Occluded oil and air are seen in a struggle to rise ; 


Upper la) 


as it drops through the oil le 
action of the oil. 


to bottom of water layer. 


to} #) 
Pee 
om 
eed 
—_ 
= 2 
bp > 
a2 
on 
S pb, 
ss 


eads, showing rapid wetting — 
have beeome fairly air-free 


through the alcohol and upon stri 


ement drops with rapidity 
se downward in heavy milky thr 


5S 
starts to diffu 
action of the oil upon the pigment which may 


Fig. 218.—Before Shaking : 


lead pi 


by the alcohol bath. 
* Under proper conditions and with sufficient agitation the lead should — 


go into the oil phase. 


Miscellaneous Chemical Tests 659 


Upper Layer Lower Layer 
Linseed Oil Water 

DUNE ee DIETING... 5.05.6. ccs. ceeeecceeeeeee. mS 

DIP UTDCT bcc lee eceeess xX 

DS oh chen oes ees ceevvveesenceeeess Xx 

Bee ern -Ptack = oo... tcc. 8 

BOM SPATE eee xX Some suspended 


below oil layer 


20 Light Green 25% on Barytes- 
Re nese teaviee es xX 


Testing the Settling Properties of Some Grades of Pig- 
ments.—In Hig. 219 is shown a series of 100 cc. cylinders 
containing oil paints made with 10 different grades of whit- 
ing. That some grades settle much more rapidly than others 
is indicated by the photograph. This method of testing the 
settling properties of pigments may be extended to practically 
any type of white pigment, and may give some useful infor- 
mation. 


FIGURE 219 


Settling Tests on paints containing whiting. 


Ten grams of each of the samples of whiting were also 
placed in 100 ce. graduated cylinders, which were then filled 
with water and shaken. The time of settling of each of these 
cylinders was measured accurately with a stop watch. The 
figures given in the table are ce. of clear water from which all 
the pigment has settled: 


660 Miscellaneous Chemical Tests 
TA Shy AO Ry QO S eo) i) QS Re 
Janis gcar ke 1325-15 110 ee 6... “41 > AO ae eee 
2 rit NS 27. 28 «= «2439 
Prin es 40 38 36  S&4 (36 47 9 97 epO meee 
doming foes es 52 48 48 67 53° 290935 nnn 
Bambtie ee ee 67. 57. 59 +73 58 | 28) ste cee 
6 malty sue oe 75° 63 . 68 76 64 409 50 0g eee eee 
Fi minin tose 775 675 72 79 68 — 3000 57 ge 
S ming. cae 79.5 705 75 81. 41 © 45 60 61 =eyeeee ene 
Ormins 81. 71.5 77 82.5 74 @)48°50 cee 
10 Min. eee 82.5 72.5 79 $4.0: 77 05206) 


SETTLING TESTS ON PAINTS 
Put out Nov. 23, 1925, 11 a. m. Oil paint placed to extent of 6-inch depth 


in 8-inch test tubes. 


1 2 3 
6 hours None None None 
24 “ None None None 
48 “ None None None 
1 week 4mm. 6mm. 4mm. 


5 months 25.3% 30.1% 22.8% 


4 b 
None None 
None None 


None None 


4mm. 2mm. 


14.1% 15.0% 


6 7 8 


None None None 


None None None 
None None None 
0 0 0 
7.5% 13.9% 12.7% 


9 
None 
None 
None 


0 
5.0% 


10 
None 
None 
None 


0 
6.3% 


50 ce. oil paint and 50 cc. mineral spirits shaken together and placed in 100 cc. 


glass cylinders. 


G6: hours * 63:62". 73:5) ea rey 
24 4 50.5 43.5 50.5 
45 44.0 386 44.8 
week 35.0 33.5 34.5 


Figures above show cc. mark to which white pigment has settled. 


65,06 2-02 

51.50 SL 
45.5 46.0 
34.8 38.5 


93.5. 93.8.) ae 
16:5 - 043 Ore 
62.5). $5.0 Bae 
43,5. 38.3 oe 


96.5 
92.0 
86.0 
61.5 


913 
87.0 


74.5 | 


54.5 


Testing the Particle Size of Pigments.—The method devel- 
oped by Stutz and Pfund for determining the particle size of 
pigments and originally published in Industrial and Engineer- 
ing Chemistry for January, 1927, has proved entirely satis- 


factory for this work. A description of his method is presented ¥ 


below. 


- 
A 
= 
C4 
we 
t 
ee 


eee ee. ee Torey) gery, 
Se ot Ae Mh omy ote 


tig 


Miscellaneous Chemical Tests 661 


“Apparatus.—A ribbon filament lamp, Iy,, (Fig. 220), is con- 
nected to a 6-volt storage battery through an ammeter and 
variable resistance. The current through the lamp can be 
kept constant, and at any desired value, over long periods of 
time. Light from this lamp is rendered parallel by means of 
the lens 4, and passes through a suspension of the pigment to 


Diagram of Particle Size Apparatus 
FIGURE 220 


be measured, contained in the cell F. This cell is of brass, 3 
inches long, with glass windows cemented in each end. The 
parallel light transmitted through the cell is focused by means 
of the lens C in the plane of the filament of the lamp L,. The 
total reflection prism, P, reflects the beam at right angles to 
its initial direction. The eye, placed at the aperture S, focuses 
by means of the lens D on the filament of lamp D2, superim- 
posed on the image of the filament of lamp Z,. A screen of 
red or green glass is introduced at the aperture S, to limit the 
wave length of the light used and eliminate color differences. 
Lamp Lz is the lamp from an optical pyrometer eye-piece. It 
is connected to a variable resistance, dry cells, and milliam- 
meter, H. By rotating the disk at the side of the box E, the 
current through the filament of lamp L, may be varied until 
the filament equals in brightness that of the image of the fila- 
Ment of the lamp L,. The intensity of the light transmitted 
by the suspension is then measured in terms of milliamperes 
of current through the lamp L:. 

‘The two objects to be matched in brightness are similar— 
that is, both are lamp filaments. There is consequently but 


662 Miscellaneous Chemical Tests 


little color difference and photometric settings can be made 
with ease and accuracy. The fact that the light beam, while 
passing through the suspension, is parallel makes each particle : 
effective in reducing the light intensity, and is therefore more 
sensitive than the use of a diverging light beam. 


a 
3 


eres of Current 


Mx 
e 


illiam 


. . Bebe 
giAt | et 
Z 370 


AREOEBE 
ut 

(Ts : | 
meee size wea Hr rb e 


FIGURE 221 
Particle Size-Relationship, Refractive Index of Vehicle 1.33 


“¢ Procedure.—Thus far the instrument has been used chiefly — 
to measure zine oxides. For this material the suspension, ~ 
which contains 0.0000694 gram of zine oxide per cubic centi- — 
meter, is made as follows: 0.20 gram of zinc oxide, 0.10 gram of — 
eum aac and 0.05 gram of saponin are ground for 8 minutes — 
with 1 ec. of 0.05 N potassium ferrocyanide solution, ina glass | 
mortar with a glass pestle; the paste is then diluted with 90 — 
ec. of water and shaken vigorously. Five cubic centimeters — 
of this suspension are diluted to 200 ce. with water, and this — 
latter is used in the determination. It is found that two ob- — 
servers can check one another within one division (2 — 
milliamperes) on the same suspension. Furthermore, two ~ 
separate suspensions made of the same material will check € 
within one and one-half divisions (3 milliamperes). . 


‘In order to keep the instrument in constant adjustment, — 3 
it is only necessary to keep the current through the lamp J; ‘ 


Miscellaneous Chemical Tests 663 


constant. However, it is more satisfactory to make use of a 
constant standard of turbidity, and to adjust the current 
through L, until this standard gives a definite reading. As 
a standard, a piece of Corning turbid glass (G632J) approxi- 
mately 5 mm. thick is placed in the cell and the cell filled with 
clear water. | 


“Results —Fig. 221 shows the results obtained on a series 
of zine oxides dispersed in water (refractive index 1.33). The 
ordinates are the readings on the opacity instrument in milli- 
amperes of current through lamp L,. The abscissas are par- 
ticle size readings in microns. For materials over 0.2 micron 
the particle size was determined by the method of Green. For 
samples under 0.2 micron the particle size was determined 


Zine Oxides of Different Particle Sizes. 


Average Method 

Particle _ of Particle 

Pigment Process of Manufacture Size u Size Detn. 
A Reheated American 1.18 Green 
B Reheated American 0.679 Green 
C Reheated American 0.484 Green 
D Reheated American 0.436 Green 
EB Special American 0.276 Green 
F French 0.246 Green 
G French 0.238 Green 
H Kadox 0.180 Count 
J Kadox 0.125 Count 


—— 


by the count method using a dark-ground illuminator and 
counting chamber. The diameter so determined is based on 
the number of particles per unit volume and is not entirely 
comparable with the diameter obtained by Green’s method. 
However, it is the only satisfactory absolute measurement that 
has been obtained for this very fine material.’ 


Testing the Physiological Action of Oils—In determining 
the possible toxic or non-toxic character of new oils which 
may come into the industry, small animals may be used. A 
record of some experiments in this direction is given below. 
In these tests the physiological effects of tung oil upon rabbits 
and dogs were recorded. An outline of the method is given 
below: 


Preliminary experiments on raw tung oil were run with 
rabbits, beginning with small doses of 1/10 ee. The animals 
were observed for any pathalogical manifestations, symptoms 


664 Miscellaneous Chemical Tests 


or organic pathology, together with the effect upon peristalsis 
of bowel movements and loosening of stool. 


On February 1, 2, 3, 4, 5, three rabbits were given 1/10, 
2/10, 3/10, 4/10, and 5/10, respectively, of raw tung oil. The 
animals exhibited no symptoms of an abnormal character; 
apparently the material did not affect their appetite and abso- 
lutely no change was observed in the dejecta. 


Large black rabbit, weighing 7 pounds, 6 ounces, was chosen 
for more intensive dosage. On February 17, 1926, given 2 ce. 
directly into stomach by syringe and catheter; no symptoms 
of anorexia, restlessness or other pathological manifestations 
were observed. Stools following day showed no change in 
character from normal. 


February 18, 1926, 5 ec. given directly into stomach by 
syringe and catheter. No symptoms were observed except 
slight indisposition to eat directly following administration 
of the preparation. No other symptomatology noted. Stools 
well formed, slightly darker than normal, and exhibited ten- 
dency to be slightly greasy; otherwise, no appreciable effect. 
Movements not increased over their normal character. 


February 23, 1926, animal’s weight the same; given 7 ce. 
directly into stomach by syringe and catheter. Animal ex- 
hibited some anorexia, some slight discomfort and indisposi- 
tion to eat shortly after administration. On February 24 


there was some increased defecation; stool soft, dark, but still — 


well formed. Character manifested was that of slight laxative 
effect. 


Testing Aluminum Stearate.—Aluminum stearate has been 
used in considerable quantities during recent years, in the 
paint and varnish industries. It is used for producing certain 
physical conditions, such as body and non-settling in prepared 
paints; waterproofing and flatting properties in interior wall 
paints, and to induce a rubbed-finish appearance in some fur- 
niture varnishes. The extent to which these conditions are 
obtained in a product appear to depend upon or be related to 
the degree of viscosity which the stearate will impart to the 
liquid, iis in turn, is influenced by the Duy texture, etc., 
of the stearate, 


Several manufacturers using aluminum stearate have expe- 
rienced difficulties due to non-uniformity of different lots re- 


Pf 
‘et 
as 


3 ate 
=! 
, 
» 
a 
aa 


Miscellaneous Chemical Tests 665 


ceived.” In the present investigation it has been found that 
different brands vary greatly in both chemical composition 
and physical properties. In view of the variation of the differ- 
ent brands, it would seem desirable to have specifications, com- 
pliance with which would insure the suitability of the material. 


Visual Examination.—For the present investigation, a num- 
ber of samples were obtained from producers and users of 
aluminum stearate. It was found that much could be learned 
concerning their suitability by visual examination. For in- 
stance, those samples which are readily soluble and which im- 
part the higher viscosities to solutions are almost invariably 
the ones that are finely divided. When stirred up in a liquid, 
colorless paraffin oil, for instance, the more finely divided stear- 
ates yield milky liquids in which no coarse particles are vis- 
ible. Other samples (coarse) contain lumps or agglomerates 
which do not break up on stirring and settle very quickly. 
When examined under the microscope some samples are seen 
to be of fine texture, and the particles, although apparently 
not crystalline, are clearly defined and fairly uniform in size. 
In other samples the material is seen to be more or less ag- 
glomerated and present a very non-uniform appearance. 
In those samples examined, which were found to contain free 
stearate acid, the particles of the acid could readily be detected 
under the microscope by their Semi-transparent appearance. 


Solubility —Aluminum stearate does not appear to dissolve 
appreciably in any solvent in the cold. It goes into solution in 
a number of solvents quite readily, however, when heated. 
When a mixture is heated, the stearate apparently softens and 
then melts as the temperature is raised, subsequently being 
dispersed through the liquid. The character of the solution 
formed by the various stearates differs greatly. For instance, 
in certain concentrations in a given solvent, one stearate will 
yield only a thin liquid while another will yield a solid gel. 
With certain samples precipitation occurs upon standing, and 
the appearance of the solution changes, while in other cases 
ho change is observable. 


Solutions of samples Nos. 1 to 7 in turpentine, mineral 
Spirits, and benzol were made. In each case 10 grams of dry 
Stearate and 200 ce. of solvent were used. The stearate was 


*The investigation to date has been facilitated by the suggestions of Dr. 
P. S. Kennedy and Mr. H. M. Johnson, of the Murphy Varnish Co. 


Miscellaneous Chemical Tests 


666 


"Gg 0} [ sofdures 

se AdUOYSISUOD 9UTVS oY} YNoqe Jo e1eM ‘paArossIp A[e}e[duIo0o 

ysnoyye ‘2 pue g sojdureg “paalossip ojvive4s ey} Jo uorzs10d 
[Lewis e@ A[uO asneoeq UIYy} 318 G 0} T So[duIes JO SUOTIN[OG :ALON 
“AYIUL yeyMouos ‘uIy} AOA *L “ON 

“UL0}}0Q 

uo uorTjerIedes yusNo.0y [Teus ‘Ay Apyysts ‘uty, ATeA “9 “ON 
‘Apnop Aysts pue mopped A[ZySIs ‘ury} AToA g pue Ff “Eg °Z “SON 
‘uoI}NyOS oni} Ajjueredde ‘1va]o pue ssoptojoo ‘uly ATOA “T ‘ON 


*MOT[eA 
are Gg pue fF ‘g ‘Z “SSeTIOT[OO e1B J), pus 
9 ‘T ‘pInbiy snosuesouoy ‘ulyy 8 04 
Ajisee pue Ajoze[dulod sA[OSSIp 1, pue g 
sojdwieg ‘onpiset sty} JO 910UL 9AlOS 
-SIp 0} 1vedde jou soop s10ul 10 InoYy 
ue IO} Sul[log penulzu0g “ysey oy} ul 
(eoo1de}, Sul[quieser) onpiset snourze 
-[a3 ‘Ayorys @ Sulave] ‘Ajojye[duiooul pues 


A[MOJ[S SATOSsIp Gg pue fF ‘g ‘Z ‘T Setdueg 


jozueg 


ee eT Sa aes AOR NED EES eg el a ra IL SE Cat Lt SE ecient See SRE ee ahaa CIA eR Ea Sh IE POT GNS., RL IK Lie RE LR I RE I Oe a ie Se PPS See 


‘ULI, OLOW JVYMOEWIOS Suleq 9 ‘ 
‘ON “4Qnoysno1yy AoUSYSTSUOD UUAIOJIUN JO STes 4ZOS a1B }, pue g “SO 
‘pinbr, uly} pue jes 
way ‘soseyd OM} JO SUTSISUOD ‘IeTIWIS ATOA o1B G pue fF ‘g ‘Z “SON 
‘qnoysnoiy} Waostun “Jos oytyM-AY[TUM “POS “T “ON 


‘MOT[eA SSO] 10 BLOW 918 
SI9YjO 9Y} eIYM ‘sse[Lojoo AT[eoyoesd 
aie 2 pue 9 ‘T ‘SON ‘fod Ys eB pue 
pinbi, uty3 Area @ ‘soseyd 4OUTYSIP OA} 
Jo ystsuod g pue pF ‘g ‘Z ‘SON ‘JOS PHS 
AoA @ SI T ‘ON ‘AdUodySISUOD UTOFIUN 
Ajjeorpoeid JO sjed SNOOSIA e1B L pue 9 
‘SON ‘pojou SI souvivedde ul duets 
-JIp o[GViloepIsuod SInoy Moy B SuIpuBys 
IaiJV ‘SoyNuIW MejJ & SuI[Iog uo Ajaye[d 


-ul0d pue A[IpBvel esAlOSSIp seidures [TV 


sqaidg 
[e19Uul 


I 


"9 “ON UPI [eoljuepy “L “ON 
*“MOTeq JNO poyeredes 
[elteyeu yusTNd.0p ‘doz uo pinbiy, Aveo pue ssejp1ofoo ‘UIYT, “9 “ON 
‘7 ON UPA [BoTJUOpUyT *G “ON 
“MOTEq uUOol}eIedes JUeTNI.0y -prinbiy ystmorjeA ‘UINT, “fF “ON 
‘doz uo pinbiy uty} Jo JUNOUe [[eUIS Y4IM 4nq *Z ‘ON 0} TBIIWIS “§ “ON 
“YSTMO[ 
-jef pue Apnoyo ‘snoosta AroA ‘AduestsuoD WAojJtun ‘poeTjes “Z “ON 
‘Apnojo yeyMoulos ‘snovsta ATA ‘AOuSYSISUOD UATOFIUN ‘po[[es “T "ON 


*IOTABOY 
yonut AtoA 1B G OJ T ‘uIyy AOA 
ere ), pue 9g Jo suoT{njog ~*MOT[aA Sse] 
IO 910Ul a1e8 Si1eyjO fsseT1o[od A][eIT} 
-ovid oie 2, puve g ‘T, ‘“suI[OOD uO 90UeB 
-1eodde ul SnosuesowoYy a1e SUOTyN[OS 
ITV ‘“seqnuru Moz eB SurTIog uo Ajeze[d 


-u0d pues ATIpveat osATOSSIp so[dures [TV 


suljuediny, 


Pe Se laa ae ee ER Na a ea ee eS EIB eae RE a Raa NB a ie Gre ef Ltt, IS OR a Fl SPC Fae ee 


Jaye, YYUOU T SUOI}BAIESGQ 


SUOI}N[OS SUIyeUL 
JO OWT} 7B SUOTPVATOSGO 


quaAlOS 


em 


O2Uag pun spinidy JoLaU]T ‘gurquadan UL SIZDADITN {O UWO1NIOY—@) ATAV 
« tl . KR - . 4 . J . A _ 


Miscellaneous Chemical Tests 667 


dissolved by heating the mixture under a reflux condenser. 
in Table 73 observations made during the test are tabulated. 
It is realized that, in actual practice, stearates would probably 
not be used in this manner, but the test, nevertheless, throws 
some light on the possible behavior of different samples when 
used in the ordinary way. 

As stated above, a definite temperature is necessary for 
bringing a given sample of stearate into solution in any sol- 
vent. The boiling points of both turpentine and mineral spi- 
its are considerably above the melting point of any sample 
of stearate. As a result the stearate melts and is dispersed 
through the liquid, forming a colloidal solution or gel. It is 
beheved that the nature of the colloidal body formed deter- 
mines to a large extent the value of a given sample as an 
ingredient of paint and enamel. It should be noted, however, 
that the turpentine solution of some samples differs markedly 
from the mineral spirits solution of the samples. 

Benzol, on the other hand, boils at a temperature consider- 
ably below the melting point of aluminum stearate. Since 
dispersion of the stearate does not occur to any considerable 
extent much below its melting point, only a small quantity of 
it is taken up by this liquid even after prolonged heating. In 
the solution made as indicated above, the liquid, when poured 
from the undissolved portion, was more nearly a true solution 
than is possible to make in even dilute solutions in turpentine 
and mineral spirits. By the use of the higher homologues of 
benzol, however, it is possible to make much more concen- 
trated and more viscous solutions. 


VIScCosITY AND CONSISTENCY 'l'ESTS 


Jelly Test—One manufacturer* of stearates uses as a con- 
trol test a so-called jelly test. This test presumably indicates 
relatively the degree of viscosity that different samples will 
impart to a liquid. It is carried out as described below using 
the apparatus shown in Fig. 222. 

Heat 10 grams of aluminum stearate with 90 cc. crude paraf- 
fin oil in a beaker of 200 ce. capacity to a temperature of 150° 
C. Stir the mixture constantly while being heated. When 
solution is complete, cool to about 10° C. 


* Mallinckrodt Chemical Works. 


Miscellaneous Chemical Tests 


668 


te 
LLL LLM 


Vie 


TNS: 


9) 
x 


FIGURE 222 me 
trength of gel made of Aluminum Stearate. — 


i 


ro" 


os 


a 


ining s 


Apparatus for determ 


Miscellaneous Chemical Tests 669 


By this treatment a jelly is formed, which varies with differ- 
ent samples from a soft oily mass to a hard, solid gel. 


The firmness of the gel thus made is tested by means of the 
apparatus shown in Fig. 83. The beaker containing the gel is 


ght (No. 4), 
Glass containers 


Veil 


Sample on 


ts After Standing One Month—Sam- 
gel. 


solid 
ly firm gel that has slumped down. 


piri 
a 


is 


FIGURE 223 


Two Samples of Aluminum Stearate in Mineral S 


ple on left (No. 1) unifo 


ir 


stency, mass 


. 


rm consl 


shows a thin liquid phase and a fa 
ted, 


< 


Inver 


placed under the plunger. On the small scale pan on top of 
the plunger another beaker is placed, and into this mercury 
or shot is poured until the gel yields under the pressure. The 
weight taken is the total weight of mercury, beaker, and 


plunger. 


670 Miscellaneous Chemical Tests 


As stated in a communication from the above concern, this 
is a rather crude test, being intended only for comparisons. 
It should be made on the various products under considera- 
tion at the same time and under the same conditions. It is 


further stated that when carried out as directed above, results — 


will not check closer than 15 or 25 grams. 


An apparatus was assembled and this test was applied to — 


the samples under investigation. It was carried out as de- 
scribed above, the gels being held at 10° C. for two hours to 
insure a uniform temperature. In check determinations the 


results differed considerably, sometimes varying as much as ~ 


20 per cent. The difference between samples is so great, how- 


ever, that even with this great variation the test may be of : 


value. In making gels of different samples for a comparative 
test the same oil should be used for all samples as the firmness 
of the gel is slightly influenced by the viscosity of the oil. 


Considerable information is obtained by observing the be- — 


havior of the material during the process of heating and the 
appearance of the gel after cooling. In the opinion of the 
writer, these observations are more important than the firm- 
ness test. 


Solutions of stearates in turpentine and mineral spirits are — 
not- suitable for consistency measurements because of their 
non-homogenous nature. Solutions in paraffin oil may gel — 


to a certain extent, even at low concentrations. Benzol solu- 


tions of definite concentration are not readily made, as a por- 


tion of the sample usually remains undissolved. A further 
difficulty arises from the fact that the consistency of the above 


solutions may change materially with the slightest agitation, 


due to a breaking down of the gel structure. For instance, 
when attempts were made to measure the viscosity of paraffin 
solutions by the tube test, it was found that the inversion of 
the tube alone was sufficient to cause a considerable change in 
consistency. 


The ‘‘viseosity induction’’ of a given stearate may, how-— 
ever, be measured by the tube method, using a xylol solution. 


Xylol gives the same type of solution as benzol, and on account 
of the high boiling point of xylol, the stearate can be heated 
sufficiently high to obtain the desired concentration. This 
method, while not entirely satisfactory, yields good results 


if definite conditions are maintained. Below a certain concen- 


Miscellaneous Chemical Tests 671 


tration, aluminum stearate dissolves on boiling in xylol to a 
colloidal solution fairly free from suspended matter. The con- 
sistency does not appear to be greatly affected by agitation 
due to handling the container, and remains constant over a 
short period of time. It changes, however with age, usually 
becoming thinner. It is, therefore, necessary to make consist- 
ency determinations at a fixed time after preparing the solu- 
tions in order to get concordant results. The exact procedure 
was as follows: 


Three and a half grams of stearate were weighed into a 
200 ce. Erlenmeyer flask and 100 ee. xylol added. The liquid 
was boiled for a few moments under a reflux condenser. The 
solution was allowed to cool under the reflux and then removed 
and stood aside for two hours, taking care that none of the 
solvent was lost through evaporation. The viscosity of this 
solution was determined in the usual way by the tube test, 
making the test at about 25° C. 

Johnson uses the following method for measuring the vis- 
cosity of paraffin oil-stearate solutions: 

Dissolve 5 grams of stearate in 100 ce. paraffin oil by heating 
to 150° C. Dip a marked spatula into the solution to the mark, 
and allow to drain until definite drops come off. Allow a drop 
to fall on a glass plate inclined at an angle. The drop will 
flow down to a greater or less distance, depending upon the 
viscosity of the solution. The distance of flow gives a relative 
measure of the viscosity of different solutions. 


CHEMICAL EXAMINATION 


Moisture.—Different lots of stearate vary in the amount 
of moisture which they contain. 

It may be determined in the usual manner—that is, by heat- 
ing about 1 gram of the sample in an oven for 3 hours at about 
105° C. A method used by Johnson gives somewhat more con- 
cordant results, and is probably more accurate in the case of 
low melting point stearates. The latter method is carried out 
as follows: 

Carefully desiccate a quantity of oleic acid by drying in a 
moisture oven for several hours. Weigh into a small portion 
of the desiccated acid about one gram of the sample. Heat at 
105° C. for 3 hours and determine the loss in weight. 

While the percentage of moisture is usually relatively small, 
it appears to influence the gelling properties of the sample, 


672 Miscellaneous Chemical Tests 


FIGURE 224 


Appearance of Three Gels Made of Aluminum 
Stearates in Paraffin Oil—Upper sample (No. 12) 
is very white and crumbly. Middle sample (No. J) 
fairly white and crumbly like polymerized Tung 
Oil. Sample (No. 6) at bottom is soft and smeary 
like vaseline. Note how it flows. 


Miscellaneous Chemical Tests 673 


or to be related to it in some way. Several users specify a low 
moisture content stearate, and at least one manufacturer at- 
tempts to keep the percentage in his product at 0.5 per cent 
or less. Upon the suggestion of E. J. Cole, several experi- 
ments were made to determine the effect on the gelling prop- 
erty of water soluble compounds that may be present. Small 
quantities of water, sodium sulphate solution, and sodium 
hydroxide solution were added to separate 10 gram portions 
of No. 1 stearate. To each, 90 ec. paraffin oil was added and 
the mixtures gelled as described in the jelly test. The samples 
to which pure water and sodium sulphate solution were added 
yielded gels apparently as firm as when nothing was added. 
The sample to which sodium hydroxide (a fraction of one per 
cent) was added, remained very thin throughout the entire 
heating, and when cold was very soft, similar to Nos. 6 and 7. 
The appearance was that of a highly refined Petrolatum Jelly 
(vaseline), for which it might serve in some arts. Apparently 
caustic alkalies have a very marked effect upon the jelling 
of Aluminum Stearate. 

In Table 74 are given the moisture content and water 
soluble in the samples examined. In general the samples of 
lowest moisture content have the smallest proportion of water 
soluble. Table 73, studied in connection with the experi- 
ments described in the previous paragraph, indicates that 
while the percentage of moisture may not in itself necessarily 
influence the viscosity of stearate solutions, yet it suggests the 
presence of compounds which do have this effect, 


Total Ash, Aluminum Oxide, and Water Soluble.—The de- 
termination of these constituents is an important part of the 
chemical examination. They are easily and quickly deter- 
mined, and are valuable indications of quality. Of the sam- 
ples under investigation, those which have the lowest viscosity 
induction values have a high percentage of water soluble, 
while in those yielding the most viscous solutions, the water 
soluble content is very low. These determinations were car- 
ried out as follows: 

About five grams of the sample was weighed into a silica 
crucible and carefully ignited over a Bunsen flame. The resi- 
due was reported as total ash. The crucible was then placed 
in a 400 ec. beaker and treated with boiling water to dissolve 
the water soluble portion. The solution was filtered through 
a quantitative paper and the paper burned in the same cruci- 


Miscellaneous Chemical Tests 


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Miscellaneous Chemical Tests 675 


ble. The second ashing represents Al,O. with the traces of 
iron and other impurities that may be present and the differ- 
ence between the two weighings represents the water soluble. 

Tron.—The presence of iron is readily detected by the yellow- 
ish red color which it imparts to the stearate solutions. The 
proportion is usually very low, less than .1 percent. In such 
small amounts it would have no effect on quality, except in so 
far as color'is concerned. Traces were found in both good and 
poor samples, hence it is believed that a quantitative deter- 
mination is unnecessary except possibly when the material 
is to be used in a white or very light-colored product. Even in 
the latter case observations of the color of solution alone would 
probably be sufficient. 

Conclusions.—The viscosity or ‘‘body’’ of solutions of alu- 
minum stearate in a given solvent varies enormously for differ- 
ent samples of stearate. Comparing the results of the firmness 
test with the viscosity of xylol solutions (Table 74), it ap- 
pears that the viscosity also varies with the solvent used. For 
instance, Sample No. 8, which showed a rather high yield 
point in the firmness test, produced a solution of very low vis- 
cosity when dissolved in xylol. 

The chemical examination has not proceeded far enough to 
draw any very definite conclusions. It appears, however, that 
the percentage of water soluble matter is important since those 
samples having the highest percentage, in general yield the 
least viscous solutions. The proportion of unneutralized 
Stearic acid and of aluminum oleate probably modify to a 
certain extent the physical properties. 


SuGcEsteD TenrTaTive SPECIFICATIONS For ALUMINUM STEARATE, 

The aluminum stearate must be finely divided and satisfac- 
tory for use in the paint and varnish industry. It must be 
white in color, and contain not over 0.1 per cent iron as FesOs. 

Moisture.—It shall contain not more than 1.5 per cent of 
moisture. | 

Water Soluble—It shall contain not more than 2.0 per cent 
of water soluble material. , 

Water Insoluble Ash.—The ash from the water insoluble 
material shall be not less than 6.0 per cent. 

Appearance of Solution—When 2 grams of aluminum stear- 
ate is dissolved in 50 grams of xylol, a practically colorless and 
fairly clear solution shall be obtained. 


CHAPTER XXXVIII 


ANALYSIS OF PAINTS 


The material presented on this subject in the previous edi- 
tions of this volume is now superseded by the A. 8. T. M. 
Tentative Methods of Routine Analysis of White Linseed Oil 
Paints, which are presented below. Following these methods 
will be found some special methods used in this laboratory 
for the identification of various oils in paint liquids. 

It is most important in taking samples of paint for analysis 
to insure uniformity. In Fig. 225 a method of thoroughly 
‘“boxing’’ paint is shown. The writer remembers some trouble 
that was experienced by one of the government bureaus a few 
years ago in securing the expected analytical results, insofar 
as pigment concentration was concerned, on shipments of 
paint to one of the government agencies. It was found that 
while the inspector had thoroughly stirred 5 gallon packages 
before taking the samples, the packages were not ‘‘boxed’’ and 
therefore the analyst failed to secure the expected results. 


A. S. T. M. TENTATIVE METHODS OF ROUTINE ANALYSIS 
OF WHITE LINSEED OIL PAINTS 
PRELIMINARY PROCEDURE 


On receipt of a sample make a record of the label, noting especially the 


brand, the name of the manufacturer, and any statements as to composition - 


and net contents. Weigh the unbroken package, open, note odor and condition 
of the contents, pour into a clean container, and mix thoroughly by pouring 
from one container to the other, finally leaving the well-mixed sample in the 
second container, which shall be tightly closed. The well-mixed sample is used 
at once for the determinations described under ‘‘Methods.” The original can 
and cover may be cleaned with gasoline, wiped dry, and then weighed. This 
weight subtracted from the original weight will give the net weight of the 
contents. If desired, the specific gravity of the paint may be determined and 
the weight per gallon calculated, and the volume of paint and the capacity of 
the container may be measured. 


REAGENTS REQUIRED 
Extraction Miature.—10 volumes ether (ethyl ether) ; 

6 volumes benzol; 

4 volumes methyl alcohol; 

1 volume acetone. 


Aqueous Sodium Hydroxide.—Dissolve 100 g. of NaOH in distilled water 
and dilute to 300 ce. 


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Analysis of Paints 


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Alcoholic Sodium Hydroxide Solution. Dissolve pure NaOH in 95-per-cent 
ethyl alcohol in the proportion of about 22 g. per 1000 ce. Let stand in a 
stoppered bottle. Decant the clear liquid into another bottle and keep well 
stoppered. This solution should be colorless or only slightly yellow when used, 
and it will keep colorless longer if the alcohol is previously treated with 
sodium hydroxide (about 80 g. to 1000 ¢c.), kept at about 50° C. for 15 days, 
and then distilled. 


Wijs Solution.—Dissolve iodine in glacial acetic acid that has a melting 
point of 14.7 to 15° C. and is free from reducing impurities in the proportion so 
that 13 g. of iodine will be present in 1000 cc. of solution. The preparation of 
the iodine monochloride solution presents no great difficulty but it shall be done 
with care and accuracy in order to obtain satisfactory results. There shall be 
in the solution no sensible excess either of iodine or more particularly of 
chlorine over that required to form the monochloride. This condition is most 
satisfactorily attained by dissolving in the whole of the acetic acid to be used 


the requisite quantity of iodine, using a gentle heat to assist the solution, if it. 


is found necessary. Set aside a small portion of this solution while pure, 
and pass dry chlorine into the remainder until the halogen contemut of the 
Solution is doubled. Ordinarily, it will be found that by passing the chlorine 
into the main part of the solution until the characteristic color of free iodine 
has just been discharged, there will be a slight excess of chlorine which is 
corrected by the addition of the requisite amount of the unchlorinated portion 
until all free chlorine has been destroyed. <A slight excess of iodine does little 
or no harm, but excess of chlorine must be avoided. 


Standard Sodium Thiosulfate Solution—Dissolve pure sodium thiosulfate 
in distilled water (that has been well boiled to free it from carbon dioxide) 
in the proportion of 24.83 g. crystallized sodium thiosulfate to 1000 ec. of the 
solution. It is best to let this solution stand for about two weeks before 
standardizing. Standardize with pure resublimed iodine, pure potassium 
biiodate, or pure KIO, (see Treadwell-Hall, Analytical Chemistry, Vol 2.) 
This solution will be approximately 0.1N, and it is best to leave it as it is 
after determining its exact iodine value, rather than to attempt to adjust 
it to exactly 0.1 N. Preserve in a stock bottle provided with a guard tube 
filled with soda lime. 

Starch Solution.—Stir up 2 to 3 g. of potato starch or 5 g. of soluble starch 
with 100 ce. of 1-per-cent salicylic acid solution, add 300 to 400 cc. of boiling 


water, and boil the mixture until the starch is practically dissolved, then — 


dilute to 1 liter. 

Potassium Iodide Solution.—Dissolve 150 g. of potassium iodide free from 
iodate in distilled water and dilute to 1000 ce. 

Acid Ammonium Acetate Solution.—Mix 150 ce. of 80-per-cent acetic acid, 
100 cc. of water, and 95 ce. of strong ammonia (sp. gr. 0.90). 


Ammonium Polysulfide—Pass H,S gas into 200 ce. of strong ammonium 
hydroxide (sp. gr. 0.90) in a bottle immersed in running water or in iced 
water until the gas is no longer absorbed; then add 200 ce. of strong ammonium 
hydroxide (sp. gr. 0.90) and dilute with water to 1000 ce. Digest this solution 
with 25 g. of flowers of sulfur for several hours and filter. 


“read Acid.”—Mix 300 ce. of H.SO, (sp. gr. 1.84) and 1800 ec. of distilled 
water. Dissolve 1 g. of c. p. lead acetate in 300 ce. of distilled water and add 


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Analysis of Paints 679 


this to the hot solution, stirring meanwhile. Let stand at least 24 hours and 
siphon through a thick asbestos filter. 


Potassium Permanganate NSolution.—Dissolve 3.2 g. of pure potassium 
permanganate in a liter of distilled water, let stand 8 to 14 days, siphon 
off the clear solution (or filter through an asbestos filter), and standardize 
as follows: In a 400-cc. beaker dissolve 0.25 to 0.30 g. (accurately weighed) 
of Bureau of Standards’ sodium oxalate in 250 ce. of hot water (SO to 90° C.) 
and add 15 ec. of dilute sulfuric acid (1:1). Titrate at once with the potas-: 
sium permanganate solution, stirring the liquid vigorously and continuously. 
The permanganate must not be added more rapidly than 10 to 15 ce. per 
minute, and the last 0.5 to 1 cc. must be added dropwise with particular 
care to allow each drop to be fully decolorized before the next is introduced. 
The temperature of the solution should not be below 60° C. by the time the 
end point is reached. (Too rapid cooling may be prevented by allowing the 
beaker to stand in a small asbestos-covered hot pkate during the titration. 
The use of a small thermometer as a stirring rod is most convenient.) The 
weight of sodium oxalate used multiplied by 0.833 gives its iron equivalent. 
The permanganate solution should be kept in a glass stoppered bottle painted 
black to keep out light. 


The iron (Fe) value of the KMnO, multiplied by 1.076 theoretically equals 
its antimony (Sb) equivalent. However, for use in determining antimony, 
the KMnO, is best standardized as follows: To 0.25 g. of pure metallic anti- 
mony in a 500-cc. Pyrex Erlenmeyer flask, add 12 to 15 ec. of concentrated 
H,SO, and 10 to 12 g. of K.SO,; heat until all the antimony is dissolved, 
cool, dilute to 250 cc. with water, add 20 cc. of concentrated HCl, cool to 10 to 
15° C., and titrate with the KMnO, solution until a faint pink color is ob- 
tained. For special work, after digesting, dilute to 100 cc. with water, add 
1 to 2 g. of Na,SO,, and boil until all the SO, is expelled. This is shown 
when no blue color is obtained with starch-iodate paper (see below); the 
volume will be reduced about one-half. Dilute to 250 ce. with water, add 
20 ce. of HCl (sp. gr. 1.19), and complete as described. 


Standard Potassium Ferrocyanide.—Dissolve 22 g. of the pure salt in water 
and dilute to 1000 ce. To standardize, transfer about 0.2 g. (accurately 
weighed) of pure metallic zine or freshly ignited pure zine oxide to a 400-cc. 
beaker. Dissolve in 10 cc. of HCl and 20 cc. of water. Drop in a small piece 
of litmus paper, add ammonium hydroxide until slightly alkaline, then add 
HCl until just acid, and then 3 ce. of strong HCl. Dilute to about 250 ce. 
with hot water and heat nearly to boiling. Run in the ferrocyanide solution 
Slowly from a burette with constant stirring until a drop tested on a white 
porcelain plate with a drop of the uranyl indicator shows a brown tinge after 
standing one minute. A blank should be run with the same amounts of 
reagents and water as in the standardization. The amount of ferrocyanide 
solution required for the blank should be subtracted from the amounts used 
in standardization and in titration of the sample. The standardization must 
be made under the same conditions of temperature, volume and acidity as 
obtained when the sample is titrated. 


Uranyl Indicator for Zine Titration.—A 5-per-cent solution of uranyl 
nitrate in water or a 5-per-cent solution #f uranyl acetate in water made 
slightly acid with acetic acid. 


680 Analysis of Paints 


Alkaline Lead Nitrate Solution—lInto 100 ce. of KOH solution (56 g. in 
140 cc. of water) pour a saturated solution of lead nitrate (250 g. in 500 ce. 
of water) until the precipitate ceases to redissolve, stirring constantly while 
mixing. Let settle, filter through asbestos, and dilute the clear filtrate with 
an equal volume of water. About 3 volumes of the lead nitrate solution will 
be required for one of the KOH. 

Ammoniacal Cadmium Chloride or Zine Sulfate Solution.—Dissolve 8 g. 
of cadmium chloride in 200 ce. of water and add 200 ec. of NH,OH (sp. gr. 
0.90), or, dissolve 200 g. of zine sulfate in 1080 ec. of water and 920 ce. of 
NH,OH (sp. gr. 0.90). 

Standard Potassium Iodate Solution.—Dissolve 3.6 g. of KIO, and 39 g. 
of KI in 1000 ce. of water. For general work the theoretical sulfur titer of 
this solution should be used; for special work, the solution may be standard- 
ized against like material, such as a lithopone of known sulfide sulfur content. 
The theoretical titer is based on standard Na,C,O, and is obtained as follows: 
To 300 ce. of water in a 600-cc. flask, preferably glass stoppered, add 10 ce. 
of concentrated HCl (sp. gr. 1.19) and 1 g. of KI.- Cool and add 10 ce. of 0.1 
N KMn0O, solution which has been standardized against Na.C,0, Swirl 
gently, stopper, and let stand for five minutes. Titrate the liberated iodine 
with standard Na.S.O, solution until the color fades. Then add 10 ce. of 
starch solution and continue the titration until the blue color is destroyed. 
Repeat the titration with the sole difference that 10 ee. of the iodate solution 
is substituted for the KMnOy, solution. Calculate the normality of the iodate 
solution. 

Starch Indicator for Sulfur Titration.—(1) To 1000 ce. of boiling water, 
add a cold suspension of 6 g. of starch in 100 ce. of water and boil vigorously 
for five minutes. Cool the solution, add 6 g. of ZnCl, dissolved in 50 ce. of 
cold water, thoroughly mix and set aside for 24 hours. Decant the clear 
oughly. (2, Optional.) Prepare an emulsion of 6 g. of soluble starch in 25 ce. 
Supernatant liquid into a suitable container, add 3 g. of KI, and mix thor- 
of water, add a solution of 1 g. of NaOH in 10 ce. of water, and stir the 
solution until it gelatinizes. Dilute to 1000 cc. with water, add 3 g. of KI, 
and mix thoroughly. 

Starch-lodate Paper.—Impregnate filter paper with a solution obtained by 
heating 2 g. of starch with 100 ce. of water, and, after solution, adding 0.2 g. 
of KIO, dissolved in 5 ce. of water. 

Standard Iodine Solution for SO,—Place 15 to 20 g. of pure KI in a liter 
flask, dissolve in as little water as possible, and then add about 6.4 g. of 
resublimed iodine. Shake until the iodine is all dissolved, dilute to the mark 
with water, and mix. This solution is approximately 0.05 N and is standard- 
ized against 0.05 N Na.S,O, to obtain its true normality. 

Standard Sodium Thisulfate Solution for SOz—Prepare and standardize 
as described above, except that 12.42 g. of pure crystallized Na.S,0,5H,O are 
used or the 0.1 N solution may be diluted with an equal volume of cold CO,- 
free water. 


METHODS 
WATER (NOTE 1) 


Mix 100 g. of the paint in a 250-ce. flask with 75 ce. of toluene. Place the 


flask in an oil bath, connect with condenser, apply heat to the bath, and distil 
until about 50 ee. of distillate have been collected in a graduate. The tempera- 


Analysis of Paints 681 


ture in the flask should be then about 105 to 110° C. The number of cubic 
centimeters of water collected under the toluene in the receiver is the per- 
centage of water in the paint. 


VOLATILE THINNER 
Weigh accurately from 3 to 5 g. of the paint into a tared flat-bottomed 
dish about 8 cm. in diameter, spreading the paint over the bottom. Heat at 
105 to 110° C. for one hour, cool, and weigh. Calculate the loss in weight as 
percentage of water and volatile thinner, subtract from this the percentage 
of water (1), and report the remainder as volatile thinner, 


NATURE OF THE THINNER 

Transfer about 150 g. of the paint to a 500-ce. flask fitted with a 2-hole cork 
stopper carrying a spray trap connected with a vertical condenser. ‘Through 
the other hole in the stopper pass an influx tube for steam. (This tube 
should dip below the surface of the paint.) Heat the flask in an oil bath 
or an air bath at 100° C. and pass through it a current of steam; with the 
steam still passing through, raise the temperature of the bath to 130° C. 
Catch the distillate in a small separatory funnel; continue distillation until 
300 ce. of water has been condensed. Portions of this water may be drawn 
from the cock of the separatory funnel from time to time, but care must be 
taken not to draw out any of the volatile thinner. Let the distillate stand 
until it separates into two layers, then draw off the water, and filter the 
_ volatile thinner through a dry filter paper into a dry flask. If the thinner 
is apparently turpentine, examine the distillate by the methods described in 
the Standard Methods of Sampling and Testing Turpentine (Serial Designa- 
tion: D 233) of the American Society for Testing Materials.* If the thinner - 
is a mixture of turpentine and mineral spirits, an approximate determination 
of the amount of turpentine may be made by the polymerization test specified 
for under turpentine. It should be noted that turpentine is slightly soluble 
in water (about 0.3 to 0.4 ce. per 100 ec. of water). 

To test for benzol, add a few drops of the distillate to a small quantity of 
a mixture of concentrated HNO, and concentrated H,SO,, and heat cautiously. 
The characteristic odor of nitrobenzol will be noted if benzol is present. 

If the thinner is apparently all mineral spirits, no further examination 
is necessary. 


PERCENTAGE OF PIGMENT 

Strain a portion of the well-mixed sample through a No. 80 sieve to remove 
any skins and weigh accurately about 15 g. of the strained paint in a weighed 
centrifuge tube. Add 20 to 30 ce. of “extraction mixture” (see “Reagents”), 
mix thoroughly with a glass rod, wash the rod with more of the extraction 
mixture and add enough of the reagent to make a total of 60 cc. in the 
tube. Place the tube in the container of a centrifuge, surround the tube 
with water, and counterbalance the container of the opposite arm with a 
Similar tube, or a tube with water. Whirl at a moderate speed until well 
Settled. Decant the clear supernatant liquid, repeat the extraction twice 
with 40 ec. of extraction mixture and once with 40 cc. of ethyl ether. After 
drawing off the ether, set the tube in a beaker of water at about 80° ©. or on 
top of a warm oven for 10 minutes, then in an oven at 105 to 110° C. for two 


* A.S.T.M. Standards Adopted in 1926 


682 Analysis of Paints 


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hours. Cool, weigh, and calculate the percentage of pigment. Grind the pig- 
ment to a fine powder, pass through a No. SO sieve to remove any skins, and 
preserve in a stoppered bottle. = 
’ an 
PERCENTAGE OF NON-VOLATILE VEHICLE . 
Add together the percentages of water, of volatile thinner, and of pigment, oe 
and subtract the sum from 100. Report the remainder as non-volatile vehicle, * 
‘ 
TESTING NON-VOLATILE VEHICLE a 
(a) Preparation of fatty acids. = 


To about 25 g. of the paint in a porcelain casserole, add 15 cc. of aqueous © 
sodium hydroxide (see “Reagents”) and 75 ce. of ethyl alcohol, mix and heat 
uncovered on a steam bath until all volatile thinner is driven off and saponifi- 
cation is complete. Add 100 cc. of water, boil, add H,SO, (sp. gr. 1.2) (8 to 
10 cc. in excess), boil, stir, and transfer to a separatory funnel to which 
some water has been previously added. Draw off as much as possible of 
the acid aqueous layer and any insoluble or precipitated matter, wash once os 
with water, then add 50 cc. of water and 50 cc. of ethyl ether. Shake very 
gently with a whirling action to dissolve the fatty acids in the ether, but not 
so violently as to form an emulsion. Draw off the aqueous layer and wash ~ 
the ether layer with one 15-cc. portion of water and then with 5-cc. portions 
of water until free from sulfuric acid. Then draw off.the water layer com- zi 
pletely. Transfer the ether solution to a dry flask and add 25 to 50 g. of 
anhydrous sodium sulfate. Stopper the flask and let stand wth occasional a 
shaking at a temperature below 25° C. until the water is completely removed Be 
from the ether solution, which will be shown by the solution becoming per- 
fectly clear above the solid sodium sulfate. Decant this clear solution, if 
necessary, through a dry filter paper into a dry 100-ce. Erlenmeyer flask. 
Pass a rapid current of dry air (pass through a CaCl, tower) into the mouth 
of the Erlenmeyer flask and heat to a temperature below 75° C. on a dry hot 
plate until the ether is entirely driven off. It is important to follow all of © 
the details, since ether generally contains alcohol, and after washing with 
water always contains water. It is very difficult to remove water and alcohol 
by evaporation from fatty acids, but the washing of the ether solution and 
subsequent drying with anhydrous sodium sulfate removes both water and — 
alcohol. Ether, in the absence of water and alcohol, is easily removed from 
fatty acids by gentle heat. If the pigment settles out rapidly in a sample 
of the paint on standing so that sufficient vehicle can be poured off; or, if a 
sufficient vehicle is obtained by centrifuging the paint, it will be advan-— 
tageous to saponify this separated vehicle and liberate and prepare the fatty 
acids as described. 

The fatty acids prepared as above should be kept in a stoppered flask and 
examined at once. : 

(b) Test for mineral oil and other unsaponifiable matter. 

Place 10 drops of the fatty acids Method (a), in a 50-cc. test tube, add 5 ce 
of alcoholic soda (see “Reagents’’), boil vigorously for five minutes, add 40 cc. 
of water, and mix: a clear solution indicates that not more than traces of — 
unsaponifiable matter are present. 

(c) Iodine number of fatty acids (Note 2). 

Place a small quantity of the fatty acids Method (a), in a sinall weighing — 
burette or beaker. Weigh accurately. Transfer by dropping about 0.15 g. = 


Analysis of Paints : 683 


(0.10 to 0.20 g.) into a 500-cc. bottle having a well ground glass stopper, or an 
Erlenmeyer flask having a specially flanged neck for the iodine test. Reweigh 
the burette or beaker and determine the amount of sample used. (If desired 
the sample may be weighed in a small wide-mouthed vial and the vial con- 
taining the weighed sample placed in the bottle or flask.) Add 10 cc. of 
chloroform. Whirl the bottle or flask to dissolve the sample. Add 10 ce. of 
chloroform to two empty bottles or flasks like that used for the sample. Add 
to each bottle or flask 25 cc. of the Wijs solution (see “Reagents’”) and let 
stand with occasional shaking for one hour’in a dark place at a temperature 
of from 21 to 23° C. Add 10 ce. of the 15-per-cent potassium iodide solution 
and 100 cc. of water, and titrate with standard sodium thiosulfate solution. 
(see “Reagents’”), using starch as indicator. The titrations on the two 
blank tests should agree within 0.1 ec. From the difference betwene the aver- 
age of the blank titrations and the titration on the sample and the iodine 
value of the thiosulfate solution, calculate the iodine number of the sample 
tested. (Iodine number is centigrams of iodine to 1 g. of sample.) 

(ad) Rosin. 

Liebermann-Storch Test.*—To about 1 g. of the fatty acids add 15 cc. of 
acetic anhydride and shake until solution is complete. Pour a few drops of 
this solution on a white porcelain plate (a crucible cover serves well) and 
add a drop of H.SO, (sp. gr. 1.53). <A fugitive violet color indicates rosin. 


Halphen-Hicks Test.;—Place about 1 g. of the fatty acids in a cavity of 
an ordinary porcelain color-reaction plate. Fill the cavity with a solution of 
one part by volume of phenol dissolved in two parts by volume of carbon 
tetrachloride. Stir the mixture. Fill another cavity of the porcelain plate 
with a solution of one part by volume of bromine and four parts by volume 
of carbon tetrachloride. Cover the whole plate with an inverted watch glass. 
If rosin is present the bromine fumes develop very soon an indigo blue color 
which persists for some time. 


ANALYSIS OF PIGMENT 

(a) Qualitative Analysis. 

A complete qualitative analysis, following the well-established methods, 
should be made and the quantitative scheme modified as required. Add acetic 
acid slowly to the pigment until all carbonate is decomposed (noting whether 
any hydrogen sulfide is evolved) ; then add a large excess of acid ammonium 
acetate solution (see “Reagents”), boil, filter, and test the filtrate for metals 
other than lead and zine (especially calcium and barium). The absence of 
calcium in this filtrate indicates that the extending pigments contain no ¢al- 
cium carbonate or calcium sulfate; the absence of barium indicates that the 
extending pigments contain no barium carbonate (Note 5). Wash the matter 
insoluble in acid ammonium acetate solution with another portion of this 
solution, and finally with hot water. This insoluble matter is dried, ignited, 
and tested for siliceous matter, barium sulfate, and titanium compounds. To 
test for the latter, place a small amount of the insoluble matter, or of the 
original sample (about 0.5 g.), in a 250-ce, Pyrex glass beaker; add 20 cc. 


* “Chemical Technology and Analysis of Oils, Fats and Waxes,” by J. Lew- 


kowitsch, Vol. 1, p. 623 (1921). 
7 Jowrnal of Industrial and Engineering Chemistry, Vol. 3, p. 86 (1911). 


684 Analysis of Paints 


= 


of concentrated H,SO,4 and 7 to 8 g. of ammonium sulfate. Mix well, and boil ca 
for a few minutes. A residue denotes the presence of silica or siliceous matter. 
Cool the solution, dilute with 100 cc. of water, heat to boiling, settle, filter, 


wash with hot 5-per-cent sulfuric acid until free from titanium. The residue 
may be tested for lead, barium, and silica. Add hydrogen peroxide to a — 


small portion of the filtrate; a clear yellow-orange color indicates the pres- 4 
ence of titanium. Boil another portion of the filtrate ih metallic tin or = 


zinc; a pale blue to violet coloration indicates titanium. . ‘Treat another por- A 


tion (about 1 g.) of the pigment with 20 cc. of HCl (1:1) and note whether 4 F 


any H,S is evolved; boil the solution for about 5 minutes, add about 25 cc. 


of hot water, filter, and wash with hot water. ; Render a small portion of the = 
filtrate alkaline with NH,OH, acidify with HCl, and add a little BaCl, © 


solution; a white precipitate (BaSO,) indicates the presence of a soluble = 


sulfate.2 To another portion of the filtrate add a little H,SO,; a white pre- 
cipitate indicates the presence of lead, soluble barium or both (some CaSO, 
may also separate) ; filter, wash to remove free acid, and treat the precipi- ¢ 
tate with a few drops of KI solution; the formation of yellow PbI, indicates c: 
the presence of lead. The white precipitate may also be treated with H,S8 = 
water; the formation of black PbS indicates the presence of lead.3 To another 
portion of the original filtrate add NH,OH until alkaline, render slightly acid 
with acetic acid, heat to boiling, and add a little K,Cr,O, solution; a yellow _ 


or orange-yellow precipitate indicates the presence of lead, soluble barium £ 


or both. “To another portion of the original filtrate add a few drops of Zz 
K,Fe(CN), solution; a white precipitate with a bluish tinge indicates the 
presence of zine. Pass into the remaining portion of the original filtrate a 
current of H,S for 5 to 10 minutes, add an equal volume of water and pass — 


H.S into the solution for about 5 minutes; filter, wash with H,S water = 
then digest the precipitate with ammonium polysulfide, filter, acidify the zg 
filtrate with HCl and warm; the presence of antimony is indicated by the ~ 


separation of an orange colored precipitate. The filtrate from the H.S pre- 
cipitate may be tested for barium, calcium, and magnesium in the usual ~ 
manner, | i 
(b) Quantitative Analysis. 
(1). Single Pigments: 
If the sample is a single pigment, follow the method described in the 


Standard Methods of Routine Analysis of White Pigments (Serial Designa- 


tion: D 34) of the American Society for Testing Materials* for eS. particular — : 
pigment in hand. a 
(2) Mixed or Composite Pigments ; - 
Moisture (Note 3) (Matter Volatile at 105-110° C.).—Place 1 to 2 g. of — 


the sample in a wide-mouth, short weighing tube provided with glass stopper. — 


Heat with the stopper removed for 2 hours at a temperature between 105 & 
and 110° C. Insert the stopper, cool, and weigh. Calculate the loss in oe 
weight as moisture (matter volatile at 105 to 110° C.). 

Loss on Ignition.—Ignite 1 g. of the pigment in a porcelain crucible over .. 
a Meker burner to constant weight (Note 4). = 

Insoluble Matter.—Moisten 1 g. of the sample with a few drops of alcohol, 
cover, add 40 cc. of HCl (1:1), boil gently for 5 to 10 minutes. Wash off 7 


* 1924 Book of :A.S.T.M. Standards. 


Analysis of Paints 685 


cover, evaporate to dryness, and heat at about 150° C. for one-half to one 
hour to dehydrate the residue. Moisten the residue with 4 cc. of concen- 
trated HCl, allow to stand a few minutes, dilute with 100 cc. hot water, boil 
a few minutes, filter hot through paper, wash with hot water (till washings 
give no test for lead and chlorine). Ignite the paper and residue in a plati- 
num or porcelain crucible, cool, and weigh total insoluble matter (Note 5). 
(The insoluble matter may be filtered off on a Gooch crucible, washed with 
hot water, dried at 105°C., cooled, and weighed; then ignited, cooled, and 
weighed, when it is desired to get the loss on ignition (combined water, 
organic matter, etc.) of same, or the insoluble matter is not to be further 
examined.) If the sample contains titanium pigment, practically all of the 
TiO, will be found in the insoluble matter along with BaSO, and siliceous 
matter. The TiO, may be determined in the insoluble matter or in a separate 
portion of the original sample by the method described in the Standard 
Methods of Routine Analysis of Titanium Pigments (Serial Designation: 
D 186) of the American Society for Testing Materials.* To determine BaSQ,, 
mix the ignited insoluble matter with about 10 times its weight of anhydrous 
sodium carbonate (grinding the mixture in an agate mortar if necessary), 
and fuse the mixture in a covered platinum crucible, heating about one 
hour. Let cool, place crucible and cover in a 250-ce. beaker, add about 
100 ce. of water, and heat until the melt is disintegrated. Filter on paper 
(leaving crucible and cover in beaker) and wash the beaker and filter thor- 
oughly with hot water to remove Soluble sulfates. Place the beaker con- 
taining the crucible and cover under the funnel, pierce the filter with a glass 
rod, and wash the residue into the beaker by means of a jet of hot water. 
Wash the paper with hot dilute HCl (1:1) and then with hot water. Remove . 
erucible and cover, washing them with a jet of hot water and removing any 
adhering precipitate. Add cautiously 20 cc. of concentrated H,SO, and evap- 
orate until fumes of H.SO, are evolved and the precipitated matter is dis- 
solved. Cool, add cautiously, with stirring, about 100 ec. of water, and boil 
a few minutes. Let the precipitate settle, filter on a weighed Gooch crucible, 
wash with hot water, ignite, cool, and weigh as BaSO,. Subtract the sum of 
the percentages of BaSO, and TiO, from the percentage of total insoluble 
matter and report the result as the percentage of insoluble siliceous matter 
(Note 6). 


If it is desired to examine the siliceous matter, unite the filtrates from the 
Na,CO, fusion and the BaSO, precipitate, acidify with HCl, evaporate to 
dryness, and proceed as in a Silicate analysis, taking cognizance of any 
TiO, that may be found, if titanium pigment were originally present. 


Total Lead (Antimony ).—Unite the filtrate and washings (total volume 
150 to 200 cc.) from the total insoluble matter, pass H.S into the solution 
until it is saturated, add an equal volume of water, and again saturate with 
H.S. Filter, wash with water containing a little hydrogen sulfide, dissolve 
in hot HNO, (1:3), washing the paper with hot water; add 10 to 20 ce. 
of H,SO, (1:1), evaporate until copious fumes of sulfuric acid are evolved ; 
cool, add about 75 cc. of water, and then about 75 cc. of 95-per-cent ethyl 
alcohol. Stir, let settle, filter on a Gooch crucible, wash with dilute alcohol, 


*A.S.T.M. Standards Adopted in 1925 


686 Analysis ot Paints 


aa 


dry in an oven at 105 to 110° C.; or, ignite gently in a radiator* or muffle, — 


cool, and weigh as PbSO, Calculate to PbO (Note (Se 


If the pigment contains antimony, filter and wash the sulfide precipitate — 
as above; then wash the precipitate with a fine jet of H,O from the paper — 


into a porcelain dish or casserole, add 25 ce. of ammonium polysulfide (see 
“Reagents”), cover the vessel, and warm the mixture at 40 to 60° C. for 10 
to 15 minutes with frequent stirring. Wash off cover, filter through the paper 


used in the first case, and wash with 2 to 3-per-cent Na,S or (NH,).S solution, | 


A RT Wy ais arin Ay 


Discard the filtrate. Dissolve the residue in hot dilute HNO, (1:3), and — 


determine the lead as PbSO,, as described above. Or, the original sulfide — 
precipitate may be discarded and the lead determined on a separate portion 


of the pigment as follows: To 1 g. of the sample in a covered beaker, add 
40 ec. of HCl (1:1) and boil gently for 5 to 10 minutes. Wash off cover and 


evaporate to dryness. Moisten the residue with a few drops of HCl, add 


about 50 cc. of hot water, boil a few minutes, filter hot through paper, and 


wash with hot water until washings give no test for lead. (If the sample 
contains no insoluble matter, the filtration is omitted.) To the filtrate add 


20 ce. of H.SO, (sp. gr. 1.84) and evaporate until dense white fumes of 
H,SO, are copiously evolved. Allow to cool, but not below 60° C., and then 
add slowly 50 cc. of water while the solution is agitated. Heat to boiling 
for several minutes in order to insure complete solution of antimony sulfate. 
Allow the PbSO, to settle out until the supernatant liquid is clear, not 


letting the temperature fall below 60° C. If the liquid does not clear quickly 


it must be heated longer. When clear, pour the solution through a weighed 
porcelain Gooch crucible with asbestos mat, decanting the solution as com- 
pletely as possible without allowing more than a very small amount of PbSO, 
to go over into the crucible. Now add 10 cc. more of H,SO, (sp. gr. 1.84) 


to the PbSO, in the original beaker, and boil for several minutes. Cool, add + 
slowly 30 cc. of water, and again heat to boiling for a few minutes; allow — 


iB 
= 
% 


the solution to cool to about 60° C. and completely transfer the PbSO, to the — 
Gooch crucible. Wash with “lead acid” (see “Reagents’”) to remove soluble — 


sulfates and finally wash free of acid with dilute alcohol (equal parts of — 


ethyl alcohol or denatured alcohol and water). Dry in an oven at 105 to 


110° C., or, ignite gently in a radiator or muffle. Calculate to PbO. Or, — 


determine as chromate as described below. 


If soluble compounds of barium or calcium are present, BaSO, and CaSO, 2 
will be included with the PbSO,. If soluble SiO, is present, it will also be 


included with the PbSO,. In such cases, the PbSO, precipitate after washing 


with dilute alcohol may be dissolved in acid ammonium acetate (see — 


‘“Reagents”) and the lead determined as PbCrO,, as described below. For — 
ordinary work, the amount of BaSO, dissolved by the acetate treatment may — 


be disregarded. 


If the pigment contains no soluble antimony, barium, or calcium compounds, 
the lead may be determined directly on the original pigment, as follows: © 
To 1 g. of the sample in a covered beaker, add 25 cc. of HNO, (1:1), and — 
boil gently a few minutes. Wash off cover, evaporate to dryness on a steam i 
bath, moisten with HNO,, add hot water, and heat a few minutes. Filter — 
and wash wtih hot water until washings are lead-free. Add 10 to 20 cc. of — 


* U. S. Geological Survey Bulletin 700, p. 33 (1919). 


Analysis of Paints 687 


H.SO, (1:1) to the clear solution, evaporate and determine lead as PbSO,. 
as above described. 

In the absence of soluble compounds of antimony, iron, aluminum, and 
barium, the following procedure may be used: Treat 1 g. of the original 
pigment with 25 cc. of HNO, (1:1) and proceed as above. To the clear 
solution, diluted to 200 cc. add NH,OH in slight excess, acidify with acetic 
acid, and add 4 to 6 cc. more of this acid; heat to boiling and add 10 to 15 ce. 
of a 10-per-cent solution of K,Cr.O,. Heat until the yellow precipitate assumes 
an orange color, let settle and filter on a weighed Gooch crucible, wash by 
decantation until the washings are colorless, finally transferring all of the 
precipitate. Then wash wth 95-per-cent ethyl alcohol and then with ether; 
dry to constant weight at 110° C., cool, and weigh PbCrO4. Calculate to PbO. 

Antimony Oxide.—Transfer 0.3 g. of a straight antimony oxide pigment, 
or 0.5 g. of a mixed pigment, to a 500-cc. Pyrex Erlenmeyer flask, add 15 ce. 
of water and 25 ce. of concentrated HCl (sp. gr. 1.19). Cover with a watch 
glass, warm on the steam bath 10 to 15 minutes to dissolve the antimony 
oxide, wash off cover, add 250 cc. of water, and 15 ec. of concentrated H.SO, 
(sp. gr. 1.84). Boil 2 minutes, cool to 10 to 15° C. and titrate to a faint pink 
tint with 0.1 N KMnOy, solution (see ‘“Reagents’’). Calculate to SbyOz. 

The above procedure gives only the antimony in the ows condition. The 
following method gives the total antimony (ows and ic forms): Transfer 
0.5 g. of a straight antimony oxide pigment, or 0.5 g. of a mixed pigment, 
to a 500-cc. Pyrex Erlenmeyer flask, add 15 ec. of H,SO, (sp. gr. 1.84), 10 g. 
of K,SO,, and a 9-cm. filter paper (to furnish carbon to act as a reducing 
agent). Place a funnel in the neck of the flask, and heat until the solution 
becomes colorless. Cool, wash off the funnel, dilute to 250 ec. with water, 
add 20 ec. of concentrated HCl, and boil 2 minutes; cool to 10 to 15° C., and 
titrate to a faint pink tint with 0.1 N KMn0O, solution. 


Note.—If the digestion with H,SO, and K,SO, (plus filter paper) is con- 
tinued after the solution becomes colorless, some of the antimony may be 
oxidized from the ows to the ic condition. In such cases, cool, wash off the 
funnel, dilute to 100 cc. with water, add 1 to 2 g. of Na.SO, and boil until all 
of the SO, is expelled. This is shown when no blue color is obtained with 
starch-iodate paper (see “Reagents’”) ; the volume will be reduced about one- 
half. Dilute to 250 cc. with water, add 20 cc. of HCl (sp. gr. 1.19), and boil 
2 minutes; cool to 10 to 15° C., and titrate to a faint pink tint with 0.1 NV 
KMnO, solution. Calculate total Sb to Sb,O,;. Subtract the Sb,O, found by 
the procedure given in the preceding paragraph from the total Sb.O, and 
calculate the residual Sb,O, to Sb.O,. 


Antimony Oxide (in the presence of appreciable amounts of iron).—Treat 
1 g. of the mixed pigment, or 0.3 g. of a straight antimony oxide pigment. in a 
covered 250-cc. beaker with 5 cc. of water and 20 ce. of HCl (sp. gr. 1.19); 
heat on the steam bath for 15 minutes, cool, wash off cover, add 8 g. of tartaric 
acid and 100 ce. of hot water, and digest a few minutes. Filter, catching the 
filtrate in a 500-cc. Pyrex Erlenmeyer flask: wash thoroughly with hot water, 
dilute to 300 ce. with hot water, and pass in H.S until the precipitation is 
complete. (If the sample contains no insoluble matter, dissolve directly in a 
900-ce. Pyrex Erlenmeyer flask. add tartaric acid. dilute. and pass in H.S.) 
Filter. wash with water containing H.S until free from HCl, return paper 


688 Analysis of Paints 


—— emacs 


and precipitate to the Erlenmeyer flask, add 15 ce. of H,SO, (sp. gr. 1.84) 
and 10 g. of K.SO,, place a funnel in the neck of the flask, and heat until the 
solution is colorless. Cool, wash off the funnel, dilute to about 250 cc. with 
water, add 20 cc. of HCl (sp. gr. 1.19), boil for 2 or 3 minutes, cool to about 
10° C., and titrate to a faint pink tint with 0.1 N KMn0Q, solution (see 
“Reagents”). Calculate the total antimony to Sb,O. 


Note.—If the digestion with H,SO, and K,SO, (plus filter paper) ‘is con- 
tinued after the solution becomes colorless, some of the antimony may be 
oxidized from the ous to the ic condition. In such cases, cool, wash off the 
funnel, dilute to 100 cc. with water, add 1 to 2 g. of Na,SO, and boil until all — 
of the SO, is expelled. This is shown when no-blue color is obtained with | 
starch-iodate paper (see ‘“Reagents”) ; the volume will be reduced about one- 
half. Dilute to 250 cc. with water, add 20 ce. of HCl (sp. gr. 1.19), and boil 2. 
minutes; cool to 10 to 15° C., and titrate to a faint pink tint with 0.1 WV 
KMnO, solution. 


Soluble Barium.—Boil the combined filtrate and washings, reduced in 
volume by evaporation if need be, from the PbS precipitate (Total Lead) to 
expel H.S. Add a slight excess of H,SO, (1:4) over the amount required to 
precipitate the barium, heat to boiling, let stand on a steam bath about one 
hour, filter on a weighed Gooch crucible, wash with hot water, dry, ignite, 
cool, and weigh BaSO, (Notes 5 and 8). Calculate to BaO. 

Alumina (Fe,O;, TiO., P,O,).—Boil the filtrate from the PbS to expel HS, 
add a few drops of HNO,, and continue the boiling a few minutes to oxidize - 
any iron that may be present. In case soluble barium was present, use the 
filtrate from that determination. To the solution containing at least 5 g. of 
NH,Cl per 200 cc. of solution, or an equivalent amount of HCl, add a few 
drops of methyl red (0.2-per-cent alcoholic solution) and heat just to boiling. 
Carefully add dilute NH,OH drop by drop until the color of the solution 
changes to a distinct yellow. Boil the solution for one to two minutes and — 
filter at once. Wash the precipitate thoroughly with hot 2-per-cent NH,Cl~ 
solution (Note 9). Ignite the precipitate, cool, and weigh as AlgOg, (Note 10y4 

Total Zinc.—(a) To the combined filtrate and washings from the alumina : 
precipitate, add sufficient NH,Cl to give 5 g. per 100 ce. of solution, and then : 
add 1 g. of ammonium acetate.* x 

Render slightly acid with acetic acid and pass in a current of H,S to ~ 
saturation. Allow the precipitate to settle completely, filter on paper, and — 
wash with a 2-per-cent solution of acetic acid saturated with H,S. Transfer — 
the precipitate and filter to the vessel in which the precipitation was effected, ‘ 
add 30 ce, of water and 10 ce. of concentrated HCl, heat until all zine is in ~ 
solution, add 200 cc. of water and a small piece of litmus paper; add strong — 
NH,OH until slightly alkaline, render just acid with HCl, then add 3 ce, of 
concentrated HCl, heat nearly to boiling, and titrate with standard potassium — 
ferrocyanide solution as in standardizing that solution (see “Reagents”). # 

(b) Zine may be determined directly on the original sample as follows 
(Note 11): Weigh accurately about 1 g. (or an amount that will give a 
purette reading approximately equal to that obtained in the standardization) é 


i 
oe 


*B. A. Gooch, “Represantative Procedures in Quantitative Chemical 
Analysis,” 1st Ed., p. 107. 


Analysis of Paints 689 


of the pigment, transfer to a 400-cc. beaker, add 30 cc. of HCl (1:2), boil 
a few minutes, add 200 ce. of water and a small piece of litmus paper; add 
strong NH,OH until slightly alkaline, render just acid with HCl, then add 
8 ce. of concentrated HCl, heat nearly to boiling, and titrate with standard 
K,Fe (CN), solution as in standardizing that solution (see ‘“Reagents”). 

(c) When iron is present, total zinc may be determined directly on the 
original sample as follows (Note 11): Weigh accurately about 1 g. (or an 
amount that will give a burette reading approximately equal to that obtained 
in the standardization) of the pigment, transfer to a 250-cc. beaker, moisten 
with alcohol, add 30 ce. of HCl (1:2), boil for 2 or 3 minutes, and add about 
100 cc. of water. Add about 2 g. of NH,Cl, make slightly alkaline with NH,OH, 
heat to boiling, let settle on steam bath, filter into a 400-cc. beaker and wash 
the residue once with hot water. Remove the 400-cc. beaker and pour dilute 
HCl on the residue, catching the filtrate therefrom in the 250-cc. beaker, wash 
a few times with hot water. Add to this filtrate 1 g. of NH,Cl and make 
slightly alkaline with NH,OH, boil, let settle, filter on paper used for first 
filtration, and wash thoroughly with hot water, catching the filtrate and 
washings in the 400-cc. beaker containing the first filtrate. Add a small piece 
of litmus paper, acidify with HCl, add 8 ce. of concentrated HCl, heat nearly 
to boiling, and titrate with standard K,Fe(CN), as above. 

(d@) With pigments containing ZnO and ZnS the ZnO may be determined 
as follows: Weigh accurately 2.5 g. of the pigment, transfer to a 250-ce. 
graduated flask, moisten with a few drops of alcohol, add about 200 ce. of 
2 to 3-per-cent acetic acid, shake vigorously and let stand for 30 minutes at 
room temperature, shaking once every 5 minutes. Then let stand at room tem- 
perature at least 5 hours, preferably overnight. Fill to the mark with 2 to 3- 
per-cent acetic acid, mix, filter through a dry paper, discard the first 25 cc. and 
transfer 100 cc. of the filtrate (corresponding to 1 g.) to a 400-cce. beaker. 
To the clear solution add 30 cc. of HCl (1:2), 100 cc. of H.O, and a small 
piece of litmus paper; add strong NH,OH until slightly alkaline, render just 
acid with HCl, then add 3 cc. of concentrated HCl, heat nearly to boiling, 
and titrate with K,Fe(CN), as above. Calculate the percentage of ZnO 
(any ZnCO, or ZnSO, is included in the ZnO). Subtract this result from the 
percentage of total Zn as ZnO, and calculate the difference to ZnS. 

Soluble Calcium.—Heat the united filtrate and washings, reduced in volume 
if need be, from the ZnS precipitate, to boiling, add 1 cc. of NH,OH and an 
excess of a hot saturated ammonitim oxalate solution. Continue the boiling 
until the precipitate becomes granular; let stand about one hour, filter, and 
wash with hot water. Ignite, cool, and weigh as CaO (Notes 5, 12, 13); or, 
place the beaker in which the precipitation was made under the funnel, pierce 
the apex of the filter with a stirring rod and wash the precipitate into the 
beaker with hot water, pour warm dilute H,SO, (1:4) through the paper 
and wash a few times. Add about 30 ce. of dilute H,SO, (1:4), dilute to 
about 250 cc., heat to 90° C, and titrate at once with standard (0.1 V) KMnO, 
solution (the temperature of the solution should not be below 60° C. when 
the end point is reached. See “Reagents’). Calculate to CaO (Notes 5, 12, 
13). (The Fe value of KMnO, X 0.502 = CaO value. ) 

Soluble Magnesium.—Acidify the filtrate from the calcium precipitate 
With HCl, add 10 ce. of a saturated solution of Na(NH,)HPO, and NH:OH 
drop by drop, with constant stirring. When the crystallin (NHs)MgPO, has 


690 Analysis of Paints 


formed, add 5 ec. excess of NH,OH. Allow the solution to stand in a cool 


place for not less than 4 hours, preferably overnight (Note 14) ; filter and s 


wash with water containing 2.5 per cent of NH,;. Dissolve the precipitate Fe 


in a small quantity of hot dilute HCl, dilute the solution to about 100 ce. 
with water, add 1 cc. of a saturated solution of Na(NH,)HPOs« and NH,OH 
drop by drop, with constant stirring, until the precipitate is again formed as 
described, and then add 5 cc. excess of NH,OH. Let the precipitate stand in~ 


a cool place for not less than 2 hours, filter on a Gooch crucible, wash with ~ 
] 


= 


water containing 2.5 per cent of NH,, ignite, cool, and weigh as Mg,P,0,— 
(Note 15). Calculate to MgO. 


Carbon Dioxride.—Determine by evolution with dilute acid and absorption 


in soda lime or KOH solution. The method given in U. S. Geological Survey 


Bulletin 700, p. 218, shows a convenient apparatus for carrying out this ; 


determination. Use from 1 to 2 g. of the pigment, depending upon the prob- 
able CO, content, following the method for the determination of carbon 
dioxide in lime described in the Tentative Methods of Chemical Analysis of 
Limestone, Quicklime and Hydrated Lime (Serial Designation: C 25-26 T) 
of the American Society for Testing Materials* (Note 16). ‘ 
Total Soluble Sulfur Compounds (Note 5).—Treat 1 g. of the pigment in 
a 400-ce. beaker with 10 cc. of H,O, 10 ce. of strong HCl saturated with 


bromine, and 5 g. of NH,Cl, digest (covered) on a steam bath for 5 minutes, % 


dilute with hot water to about 200 ec., boil for 5 minutes, filter to separate 
any insoluble matter, and wash thoroughly with hot water. Nearly neutralize 


the clear solution in a covered beaker with NaOH solution, complete the — 
neutralization with dry Na,CO, and add about 2 g. more of this reagent. — 


TERRA ah Shy 


Boil 10 to 15 minutes, wash off cover, let settle, filter, and wash with hot — 
water. Re-dissolve the precipitate in HCl (1:1), reprecipitate with Na.CO, ° 
as above, filter, and wash thoroughly with hot water. Acidify the united — 


filtrates with HCl, adding about 1 cc. in excess. Boil to expel bromine, and ; 
to the clear boiling solution add slowly with stirring.an excess of a 10-per- — 


cent BaCl, solution. Let stand on a steam bath for at least 1 hour, filter > 


on a weighed Gooch crucible, wash thoroughly with boiling water, dry, ignite — 


4 


at a dull red heat, cool, and weigh as BaSO,. This will include soluble sul- * 
fates, SO, formed from SO, and the SO, that is formed from sulfide sulfur ie 


(Note 8). 


Soluble Sulfate (Note 5).—Treat 1 ¢g. of the pigment with 10 ce. of H,O 7 
and 10 ce. of concentrated HCl and 5 g. of NH,Cl. Boil until H.S is expelled, — 
adding more HC] (1:1) if necessary; dilute with hot water to about 200 cec., — 


Pa SF a a 


boil for 5 minutes, filter to separate any insoluble matter, and wash thor- a 
oughly with hot water. Nearly neutralize the clear solution with NaOH solu- & 
tion and make a double precipitation with Na.CO,, as in preceding method, — 


finally weighing as BaSO,, as described above (Note 8). 
Sulfide Sulfurt (Note 17).—Place 0.5 to 1 g. of the pigment in a flask with 
about 10 g. of “feathered” or mossy zine, add 50 ec. of water; insert @ 


stopper carrying a separatory funnel and an exit tube. Run in 50 ce. of 


concentrated HCl from the funnel, having previously connected the exit tube — 
to two absorption flasks in series; the first flask contains 100 cc. of alkaline ~ 


* See p. 290 Footnote. A.S.T.M. 1926. 
+ Evolution Method of W. G. Scott, “White Paints and Painting Materials,” 
p. 257; see also Blair, ‘“‘The Chemical Analysis of Iron.” 


Analysis of Paints 691 


lead-nitrate solution (see “Reagents’’), the second flask, 50 ce. of the same 
solution as a Safety device. After all of the acid has run into the evolution 
flask, heat slowly, finally boiling until the first appearance of steam in the 
first absorption flask. Disconnect, let the lead sulfide settle, filter, wash 
with cold water, then with hot water till neutral to litmus paper and wash- 
ings give no test for lead. Dissolve the PbS precipitate in hot, dilute HNO, 
and determine the lead as PbSO:. Calculate to S. For very rapid work, the 
evolved H.S may be absorbed in an ammoniacal CdCl, or ZnSO. solution 
(see “Reagents”) contained in 2 flasks connected in series, the contents of 
the absorption flasks washed into a vessel with cold water and diluted to 
about one liter, acidified with concentrated HCl and titrated with standard 
potassium iodate solution (see “Reagents’’), using starch indicator (see 
“Reagents’’). 


Sulfur Dioxide (Note 18).—Transfer 10 g. of the pigment to a suitable 
flask, insert a stopper fitted with a separatory funnel and a spray trap delivery 
tube (Note 19), and attach the latter to a condenser. Place about 150 ce. 
of HCl (1:3) in the funnel, the stopcock being closed (Note 20), connect 
the other end of the condenser with a delivery tube which passes through 
a 2-hole stopper and extends nearly to the bottom of an absorption flask; 
through the other hole of the stopper connect a tube or flask to serve as a 
safety device. Place 25 cc. of 0.05 N iodine solution (see “Reagents”) in the 
absorption flask (dilute with water if need be) and 20 ce. of 10-per-cent KI 
solution in the safety tube; fit stopper in the absorption flask. Open the 
stopcock and allow the acid to slowly enter the flask. Before all of the acid 
is admitted, air (washed with NaOH solution) is forced through the top of 
the separatory funnel (about 2 bubbles per second in the KI solution). Boil — 
the solution 3 minutes with the air passing through, then remove the source 
of heat and pass air through for 30 minutes. Disconnect the absorption 
vessels, wash the KI solution into the iodine solution, and titrate at once with 
0.05 N Na,S,O, solution, using starch indicator. Run a blank determination 
in exactly the same manner except for the omission of the pigment. Subtract 
this figure from the previous one and calculate the final result. to SO, 
(1 ec. 0.05 N I = 0.0016 g. SO,). 


Matter Soluble in Water.—Transfer 2.5 g. of the pigment to a graduated 
250-ce. flask, add 100 cc. of water, boil for 5 minutes, cool, fill to mark with 
water, mix, and allow to settle. Pour the supernatant liquid through a dry 
filter paper and discard the first 20 cc. Then evaporate 100 cc. of the clear 
filtrate to dryness in a weighed dish, heat for one hour at 105 to 110° C., 
cool, and weigh. Calculate the percentage. The nature of this may be deter- 
mined by further examination, as the percentages of SO, and CaO may be 
indicative. 

NOTES 

1. A convenient apparatus for this determination is shown in Fig. 1 (b) 

of the Standard Method of Test for Water in Petroleum Products and Other 


Bituminous Materials (Serial Designation: D 95) of the American Society for 
Testing Materials.* 


2. If appreciable amounts of resin or of unsaponifiable matter are found 
to be absent in the vehicle of a paint, the iodine number of the fatty acids 
gives the best indication (though not proof) of the presence of linseed oil. 


* 1924 Book of A.S.T.M. Standards. 


692 Analysis of Paints 


a 


An iodine number of less than 175 (Wijs) for the fatty acids is an indication 
that the non-volatile vehicle was not pure linseed oil. 

3. On an extracted and dried pigment, this determination is of little value, 
If the original paint contained gypsum, a part of the combined H,O of the 
latter will be driven off in the drying of the extracted pigment and in the 
“moisture” determination. 

4. This determination may serve as a rough or approximate check in Many 
cases on the CO,, H,O, ete. 

5. If the original sample contained BaCOg and PbSO4, CaSO, or other 
soluble sulfate. the so uble Ba will ferm with the soluble sulfate a precipitate 
of BaSO: which will be determined as “insoluble matter.” If the sample 
contained SrSO, cr SrCO,, some SrSO, may be counted as BaSO,, some Sr 
will count as soluble barium. and some may be counted as CaO. This element 
is not separated, as it probably will not be encountered, or will be present as 
an impurity in the Ba and Ca compounds. 

6. Any soluble Al,O, (Fe,O,) and in most cases MgO, and sometimes some 
CaO, come from the siliceous pigment used. MgO generally denoted the 
presence of asbestine. : 

7. It is not possible to determine the amount of basic lead carbonate and 
lead sulfate when carbonates or soluble sulfates of other metals, such as 
calcium, are present. Also neither basic lead carbonate nor basic lead sulfate 
are definite compounds, 

8. This will include any BaSO, that may have been dissolved as such. The 
weighed precipitate should be tested for CaSO, and if present, it should be 
removed by treating with hot dilute HCl, filtering, washing, igniting, and again 
weighing. 

9. For very accurate work, or when the precipitate is large, the precipitate 
should be dissolved in HCl (1:1) and the precipitation repeated. 

10. This precipitate may also contain Fe,O;, TiO,, and P,O;. 


= yet Fist 


11. If the sample contains antimony, it should be precipitated by H,S in the — 


hot acid solution, filtered off, washed, and the filtrate neutralized, etc., for zinc. 
The H.S precipitate may also contain PbS. If no sulfide separation is made, 
any cadmium present will be counted as zine. 

12. Care must be exercised in this washing, as 1000 ce. of boiling water 
will dissolve over 0.01 g. of CaC,O,. 

13. For more accurate work, the CaC,O, precipitate should be ignited, 


cooled, cautiously moistened with water, redissolved in HCl and the solution — 


diluted to 100 cc. Then NH,OH should be added in slight excess, the liquid 
boiled, and filtered and washed if a precipitate appears. Then reprecipitate 


the Ca with NH,OH and (NH,).C,0, as above, filter, wash, ignite, cool, and 


weigh; or, titrate as described. 

14. The less the amount of magnesium present, the longer the precipitate 
must be allowed to settle. 

15. If the sample contained manganese, it will be caurht in large part with 


the Mg.,P.0,. If desired, Mn may be determined by dissolving the Mg.P.0, $ 


in HNO, and applying the bismuthate method. 


16. If the sample is high in sulfide, e. g.. contains a high percentage of | 
lithopone, grind 1 to 2 g. of the pigment with dry K.Cr.O,. transfer to the © 
evolution flask, add 50 cc. of water, and run in H.SOs (1:1) from the sep- — 
aratory funnel. Or, place at the front of the purifying and drying train 2 ~ 


tube containing acidified CuSO, solution, KMnO, solution, or CrO; solution. 


17. The percentage of sulfide sulfur can be calculated from the percentages ‘ 


of total zinc and zinc soluble in 2 to 3 per cent acetic acid, assuming the sulfide 
to be ZnS. See Method (d) under determination of zine. 

18. This method is not applicable in the presence of sulfides decomposable 
under the conditions given. 

19. A Knorr CO, apparatus is very convenient. In this case, the vertical 


condenser may be connected with an absorption tower containing the iodine — 


solution, followed by the KI solution in a suitable tube. 

20. To minimize, if not eliminate, any possible oxidation by the air, add 
about 1g. (in one piece) of NaHCO, to the evolution flask, then add the acid 
directly to the flask, omitting the separatory funnel and the current of air. 
Boil the solution until about 50 cc. of distillate has passed over. 


Analysis of Paints 693 


CALCULATIONS 

The calculation of the component pigments of a mixed or combination 
pigment may be a somewhat difficult matter. Certain assumptions must be 
made, depending upon the complexity of the mixed pigment, as to the com- 
position or formulas of component pigments and as to the manner in which 
the acidic and basic radicles are combined. Add any A1,0, (Fe.O,) found 
in the soluble portion to the siliceous matter and report the sum as “‘Insoluble 
siliceous matter,” unless the soluble Al is high; in this case, an aluminate is 
probably present, and the Al,O, should be reported as AI,O,. If a small 
amount of soluble Mg is found, it should also be added to the siliceous matter. 
If the soluble Mg is high, the presence of MgCO, is indicated, and the MgO 
is calculated to MgCO, as pointed out below. The insoluble siliceous matter 
reported should be based on the weight obtained on drying the total insoluble 
matter at 105° C. if the combined H,O contained therein is to be considered. 

In the absence of ZnS or TiO., report BaSO:s as BaSO,. If ZnS is present, 
calculate the BaSO, equivalent by multiplying by 2.85; report sum of ZnS + 
BaSO, as “lithopone.” If TiO, is present, calculate the BaSO, equivalent by 
multiplying by 3.17; report sum of TiO, + BaSO, as “titanium pigment.” 
Report residual BaSOs as BaSO,. If TiO, is present and BaSO, is absent ar. 
is present in a smaller amount than would be indicated by the above factor, 
then report TiO, as TiO., and BaSO: as BaSO,. If CaCO,, CaSO,, BaCO,, and 
MgCO, are absent calculate CO, to basic carbonate white lead, (PbCO,), Pb 
(OH)., and soluble SO; to PbSO:. Any excess of Pb is calculated to PbO, 
added to the PbSO,, and the sum reported as basic lead sulfate; or, multiply 
the sum of PbSO: + PbO by 0.058 to obtain the ZnO; add this result to the 
PbSO, + PbO and report as basic sulfate white lead. (The ZnO factor is : 
based on the assumption that the average composition of commercial basic 
sulfate white lead is: 78.5 per cent PbSO,, 16.0 per cent PbO, and 5.5 per cent 
ZnO.) Lead oxide (PbO) should not be reported except in the presence of 
PbSO:; unless the entire analysis is reported in the elementary or oxide 
form. 

If the sample contains CO, but no soluble SO,, calculate total Pb to basic 
carbonate white lead, (PbCO,;), Pb(OH),; calculate residual CO, to CaCoO,, 
then to BaCO, and MgCO, if soluble Ba and Mg should be present in sufficient 
amounts to indicate the presence of these carbonates. The CO, result will be 
an index of this. A small amount of residual CaO is probably from the 
Siliceous matter and should be added to the insoluble siliceous matter. 

A small amount of soluble Ba may be from the CaCO, used or may be 
due to the solubility of BaSO, if this compound is present in the original 
pigment. This Ba may be calculated to BaSO: and added to the BaSO, found 
in the insoluble matter. 

If the sample contains soluble SO, but no CO,, calculate CaO to CaSO, 
or CaSO, 2H,0; residual SO, to PbSO,; add residual PbO to PbSO: and report 
Sum as basic lead sulfate; or, multiply PbSO: + PbO by 0.058 and add the 
result to the PbSO, + PbO, and report the total as basic sulfate white lead. 

If the sample contains CaCO, (MgCO,, BaCO,) and also basie sulfate 
white lead, or CaSO, and basic carbonate white lead; or a mixture of these; 
it is not possible to determine or calculate the amount of PbCO, or PbSOs with 
any degree of certainty (Notes 3 and 5). The presence of appreciable amounts 
of CaO and SO, in the water-soluble matter indicates the probable presence 


694 Analysis of Paints 


of CaSO, in the original pigment. The following arbitrary calculations may 
be made; calculate water-soluble SO, to CaSO, or CaSO. 2H,0, subtract this 
SO, from total soluble SO, and calculate the remainder to PbSO,; calculate 
residual CaO to CaCO,, and then residual CO, to (PbCO,), Pb(OH),. If there 
is an excess of CO,, calculate to MgCO, or BaCO,, if the amounts of soluble 
Mg and Ba indicate the probable presence of these carbonates. Add residual 
PbO to PbSO, and calculate, as above, to basic sulfate white lead. The proce- 


dure followed by the Federal Specifications Board should be noted.* 
Report total antimony as Sb,O.. 


Calculate sulfide sulfur to ZnS, subtract the Zn equivalent to the S from 
the total Zn, then subtract the Zn required for the basic sulfate white lead, 
and report the remainder as ZnO. 

Report moisture, loss on ignition, SO., and matter soluble in water directly. 


Detection of Tung Oils——Chinese wood oil may be de- 
tected in the vehicle by mixing the oil with an equal volume of a 
saturated solution of iodine in petroleum ether, allowing the 
mixture to stand in direct sunlight. Under these conditions, 
a peculiar, insoluble, spongy polymer of one of the fatty acids 
of Chinese wood oil is shown. 


Quantitative Determination of Tung Oil in Paints and Var- 
nishes.t+—Hnough varnish to contain 1 to 2 grams Tung Oil 
after having evaporated the thinners, is extracted with ice-cold 
petroleum ether (40° to 60° C.) containing 40 % absolute alco- 
hol. The extract contains the oil and is evaporated in a 
weighed dish containing 1 to 2 gms. sand to about 10 ee. Then 
i gm of sodium nitrate followed by 6 cc. 6N. H2S0s is added, 
vue mass stirred, and then set aside for 30 minutes. If tung 
oil be present a yellow spongy mass separates. Ten ce. of 
water is now added with stirring and the liquid decanted 
through a hardened paper. The precipitate is further washed 
by decantation with 3 or 4 5-ce. portions of petroleum ether 
containing 5% absolute alcohol, then with H.O, until free from 


* Federal Specifications Board Specification No. 10 for “White Paint and 
Tinted Paints Made on a White Base, Semipaste and Ready Mixed”; Bureau 
of Standards Circular No. 89, 2d Hd., p. 2: “The total lead dissolved by dilute 


acetic acid and hot acid, ammonium acetate, weighed as lead sulfate, and this * 


weight multiplied by the factor 0.888 shall be considered white lead. (It is 
not possible to determine the amount of lead carbonate and lead sulfate when 
carbonates or sulfates of other metals, such as calcium, are present. Also 
neither basic lead carbonate nor basic lead sulfate are definite compounds. 


The factor to convert PbSO, to (PbCO,),.Pb(OH), is 0.854, to convert PbSsO, 
to PbSO: PbO is 0.868, and to convert PbSO, to (PbSO,), PbO is 0.918. The = 


arbitrary factor used under this specification is the mean of the largest and 
smallest of these three factors. )” 
+J. N. Goldsmith, J. Oil & Col. Chem. Assn. 78 342, (1926). ‘ 
Fox & Bowles. Analysis of Pigments, Paints, and Varnishes 1927, p. 168. — 
D. Van Nostrand. ¥ 


Analysis of Paints ees 


sulfate; then with 2 or 3 5-cc. portions of absolute alcohol and 
finally with 3 or 4 5-ce. portions of petroleum ether. The 
precipitate may be dried in air at 100° C. and multiplied by 
0.85 to convert to tung oil. 


See also tung oil tests in Chapter XXIII. 


Detection of Fish Oil—Fish oil may ordinarily be detected 
by its odor, especially if the sample be heated and rubbed on 
the palm of the hand. 


The oldest positive method is by Marecusson and Huber* and 
is as follows: 


Ten ce. of the tatty acids of the oil are shaken in a cylinder 
with 200 ec. Br solution containing 1 volume Br, 28 volume 
acetic acid, and 4 volume of nitrobenzene. Fish oil and lino- 
lenic acid yield a precipitate on one hour’s standing. Any 
precipitate is filtered off, washed with ether, dried and 
weighed. ‘T'o differentiate between the octabromides of fish 
oil, fatty acids and the hexabromides of linolenic. acid, 
the precipitate is boiled for one-half hour in benzol in an 
Erlenmeyer flask under a reflux condenser, 2 grams of pre- 
cipitate requiring 100 ec. benzol. The hexabromides dissolve, 
while the octabromides do not. The melting point of the resi-. 
due, if from fish oil, is about 200° C. The method will detect 
about 10% of fish oil. 

Tsujimoto; has developed a method for detecting fish oil 
which depends upon the formation and precipitation of iodine 
chlorine addition compounds of the highly unsaturated acids 
occurring in fish oil, but not of linolenic acid. Dissolve 0.5 
gram of the fatty acids in 10 ce. ether and add 3 5-ce. of a 1.N 
glacial acetic acid I Cl (Wijs) solution. Keep the solution, 
with frequent shaking, for two hours at 15 to 20° C. 

If fish oil be present to the extent of 1% of Japanese sar- 
dine oil, or 5% of herring oil, a precipitate will be formed. 
This method has been criticized by Davidsont who states 
that several European fish oils failed to Bye a precipitate 
when submitted to this test. 


Other Oils.—The presence of soya bean and other vegetable 
oils is in some cases difficult to detect. The iodine numbers 


* Marcusson & Huber, Seifenseider Ztg. p. 249 (1911), C. A. 5 1847 (1905). 
+ J. Soc. Chem. Ind. Japan, 29 561 (1926) C. A. 27 661 (1927). 
~Chem. Umschau Fette, Oile u Wachse 34 49 (1927). C. A. 27 1890 
1927). 


696 Analysis of Paints 

of these oils, however, are all lower than that of linseed oil. 
Tt must be remembered, however, that the iodine number of 
boiled linseed oil is lower than that of raw oil and that the 
iodine number of oils extracted from many paints is usually 


lower than shown by the original oil. In the presence of con- — 


siderable quantities of drier, it is always advisable to extract 
the fatty acids from oil and make the iodine determination 
upon them. Determination of hexabromides gives best in- 
formation as to type of oil present. 

The distillate from the paint vehicle may consist of turpen- 
tine, mineral distillates, benzol and similar solvents. The 
presence of benzol is readily detected by adding a few drops 
of the distillate to a small quantity of a mixture of concen- 
trated nitric and sulphuric acids. Upon heating this mixture, 
the characteristic odor of nitro-benzol will be recognized if 
benzol is present. Mineral distillates from petroleum are 
easily detected by the polymerization method given under 
Turpentine Specifications. 


ee ee ee SENT ees eT 


iC renpe ‘= thy 


iis on: 


CHAPTER XXXIX 


ANALYSIS OF WHITE PIGMENTS 


The methods for the analysis of white opaque as well as 
white inert pigments, given in the preceding editions of this 
volume, and which were used in the development of standard 
methods are now replaced by these standard methods of the 
A.$. T. M. which are included below, following specifications 
for many of these products. Methods for the analysis of white 
inert pigments are given on page 704. Following this presenta- 
tion is given a special method for the determination of carbon 
dioxide in white pigments, as well as a special gravimetric 
method for the determination of zine in white pigments. 
Other special methods are presented for determining the per- 
centage of antimony in white pigments, see page 683. 


A. 8S. T. M. STANDARD SPECIFICATIONS FOR 
BASIC CARBONATE WHITE LEAD 


1. These specifications cover what is commonly known as Basic Carbonate 
White Lead as used as a pigment and in putty, purchased either as dry pig- 
ment or ground in oil to form a paste. 


I. MANUFACTURE. 

2. (a) Dry Pigment.—The pigment shall be the product made from metallic 
lead and shall have a composition corresponding approximately to the formula 
2PbCO;.Pb(OH),. It shall be thoroughly washed after corroding, shall be 
free from impurities and adulterants, and shall meet the requirements given 
in Section 3. 

(b) Paste.—The paste shall be made by thoroughly grinding the specified 
pigment with pure raw or refined linseed oil. 


II. PROPERTIES AND TESTS. 
3. (a) Dry Pigment.—The pigment shall conform to the following re- 
quirements: 


MaxIMuM. MINIMUM. 
Coarse particles retained on a Standard No. 325 


IIIT ICES OOTIY 5.5, gs xa e's 0 ne © adie'sie is becom wre 1.0 ee 
SP CAEDOMALEG, DEL CONDE... test ce enone 75.0 65.0 
Total impurities, including moisture, per cent.. 2.0 


*For determining coarse particles, screen 3 in. in diameter are recom- 
mended. The screen cloth is described as follows: No. 325 cloth of the U. 8. 
Standard Sieve Series should be made of wire 0.036 mm. (0.0014 in.) in 
diameter, a tolerance of 15 per cent under and 35 per cent over being allowed 
on this diameter. The average opening between adjacent parallel wires 
should be 0.044 mm. (0.0017 in. ) the tolerance being S per cent with the addi- 
tional limitation that the maximum opening shall not exceed 0.044 mm. by 
more than 90 per cent. 


698 Analysis of White Pigments 


The color and color strength, when specified, shall be equal to that of a 
sample mutually agreed on by buyer and seller. 

(b) Paste—The paste as received shall not be caked in the container 
and shall break up readily in oil to form a smooth paint of brushing con- 
sistency. The paste shall conform to the followirig requirements: 


MAXIMUM. MINIMUM. 


Pigment (as specified above), per cent....---- 92 90 

Linseed oil, per Cent.........e sere ree eerecees 10 8 

Moisture and other volatile matter, per cent... OF a 

Coarse particles and skins (total residue re- 

tained on a Standard No. 325 screen* based 

on pigment), per Cent......-ee seer ee eeeees 

4. One sample shall be taken at random from each lot of 1000 packages 

or less. If the packages are of such size that 1000 packages amount to more 
than a carload, one sample shall be taken at random from each carload. 


1.5 


A. S. T. M. STANDARD SPECIFICATIONS FOR 
BASIC SULFATE WHITE LEAD 


1. These specifications cover the pigment commonly known as “basic sul- 
fate” white lead. The pigment may be purchased in the dry form or ground 
in oil to form a paste. 


I. MANUFACTURE. 
_ (a) Dry Pigment.—The pigment shall be the sublimed product prepared 
from lead sulfide ores, and shall be free from impurities and adulteration. . — 
(b) Paste-—The paste shall be made by thoroughly grinding the specified 
pigment with pure raw or refined linseed oil. 


Il. PROPERTIES AND TESTS. 
3. (a) Dry Pigment.—The dry pigment shall conform to the following 


requirements : 
MAXIMUM MINIMUM 
Coarse particles retained on a Standard No. 325 
sereen.* per Cent... ...eeee eee e ee rerecees 4 1.0 hile 
Lead oxide, per Cent........ eee cree eee eer ees 18.0 PUD) 
9.0 


Zine oxide, per CeNt...... eevee eeeeeecercces 
Total impurities, including moisture, per cent.. 1.0 
The remainder shall be lead sulfate. 

The color and color strength, when specified, shall be equal to that of a 
sample mutually agreed on by buyer and seller. 

(b) The Paste.—The paste as received shall not be caked in the container 
and shall break up readily in oil to form a smooth paint of brushing con- 
sistency. It shall mix readily in all proportions, without curdling, with lin- 
seed oil, turpentine, or volatile mineral spirits or any combination of these 


substances. 


* See footnote on page 697. 


re) eee, Se 


a 
4 
E 
§ 
4 
: 
‘ 


Analysis of White Pigments 699 


The paste shall conform to the following requirements: 


MAXIMUM MINIMUM 
RRM TIO T COUT. y c)..s fo cic ssc en vc ccceevcscvees 91.0 89.0 
RM UAT CL CONG. 5 eas os sw cine ccc ce ne bees én 11.0 9.0 
Moisture and other volatile matter, per cent... 0.7 cote 


Coarse particles and skins (total residue re- 
tained on a Standard No. 325 screen,* based 
PremisMment)y, Per Cent*® 2... 6. be we ce we le 1.5 


4. One sample shall be taken at random from each lot of 1000 packages 


or less. If the packages are of such size that 1000 packages amount to more 
than a carload, one sample shall be taken at random from each carload. 


A. S. T. M. STANDARD SPECIFICATIONS FOR 
ZINC OXIDE 


1. These specifications cover the pigments commonly known as “Zine 
White,” or Zine Oxide, purchased either in the form of any pigment or ground 
in oil to form a paste. 


I. MANUFACTURE. 

2. (a) Dry Pigment.—The pigment may be made by the American process 
direct from the ore, or by the French process from spelter. The order or con- 
tract shall state which is desired. 

(b) Paste.——The paste shall be made by thoroughly grinding the specified 
pigment with pure raw or refined linseed oil. 


II. PROPERTIES AND TESTS. 
3. (a) Dry Pigment.—The pigment shall conform to the following re- 
quirements: 


AMERICAN PROCESS FRENCH PROCESS 
MaAxIMUM MINIMUM MAxIMUM MINIMUM 
Coarse particles retained on a 
Standard No. 325 screen,* per 


SU a, 2 rr 10 i 1.0 see 
eemcroxide, per cent:.........- uke 98 ne 99 
otal sulfur, per cent........ 0.2 ak Ape 
Total impurities, including 

moisture, per cent........ 2.0 ah 1.0 


The color and color strength, when specified, shall be equal to that of a 
Sample mutually agreed on by buyer and seller. , 

(b) Paste.—The paste as received shall not be caked in the container and 
Shall break: up readily in oil to form a smooth paint of brushing consistency. 
The paste shail conform to the following requirements as to composition: 


MAaxIMUM MINIMUM 
MOC COCTIL. 6 os en so este ne 8 Saeed ale wae es 86 SO 
0S O02) a 2) a 20 14 


Coarse particles and skins (total residue re- 
tained on a Standard No. 325 screen* based 
mammemont), POT CONC. .... 66600 eece cua nnn 1.5 

Moisture and other volatile matter, per cent.... 0.5 


* See footnote on page 697. 


"i ee 


700 Analysis of White Pigments 


4, One sample shall be taken at random from each lot of 1000 packages 
or less. If the packages are of such size that 1000 packages amount to more 
than a carload, one sample shall be taken at random from each carload. 


A. 8. T. M. STANDARD SPECIFICATIONS FOR 
LEADED ZINC OXIDE 


1. These specifications cover the pigment commonly known as Leaded Zine 
Oxide, and consisting of zine oxide with varying amounts of lead compounds, 
purchased either as dry pigment or ground in oil to form a paste. 


I. MANUFACTURE, 
2. (a) Dry Pigment.—The pigment shall be made by the collection of the 
fumes or dust arising from furnace operations on materials containing zinc. 
(b) Paste-—The paste shall be made by thoroughly grinding the specified 
pigment in pure raw or refined linseed oil. 


II. PROPERTIES AND TESTS. 
3. (a) Dry Pigment.—The pigment shall conform to the following re- 
quirements: att ee 
H1GH-LEADED LOW-LEADED 
MaximMuM MinriMuM MaxiMuM MINIMUM 


Coarse particles retained on a 
Standard No. 325 screen,* 


per Ce@lt..4 <5 os sae ce ees 1.0 aie 1.0 id Ye 
Zine oxide (ZnO) per cent.... .-. 60 cans 93 
Water-soluble salts, per cent.. 1.0 Be 1.0 ve 
Total impurities, including 

moisture, per cent........ 1.5 oes 1.5 a 


The remainder shall be normal or basic lead sulfate. 


The color and color strength, when specified, shall be equal to that of a 
sample mutually agreed on by buyer and seller. j 

(b) Paste.—The paste as received shall not be caked in the container and 
shall break up readily in oil to form a smooth paint of brushing consistency. 
The paste shall conform to the following requirements as to composition ; 


MAxIMUM MINIMUM 
Pigment, per Cent... ss i524 se so cies 0 alo eee 88.0 Le 
Linseed oil, per Cents. 0. icc. © cw ao ee wire ee 17.0 12.0 
Moisture and other volatile matter, per cent... 0.5 ae eee 


Coarse particles and skins (total residue re- 
tained on a Standard No. 325 screen* based 
on pigment), per Cent........esseeeeecrcees 1.5 he 
4. One sample shall be taken at random from each lot of 1000 packages 
or less. If the packages are of such size that 1000 packages amount to more 
than a carload, one sample shall be taken at random from each carload. 


A. 8S. T. M. STANDARD SPECIFICATIONS FOR 
LITHOPONE 


1. These specifications cover the pigment consisting of zine sulfide and 
barium sulfate, commercially known as lithopone, The pigment may be pur- 
chased in the dry form of ground in oil to form a paste. ony 


* See footnote on page 697. 


Analysis otf White Pigments 701 


I. MANUFACTURE, 


2. (a) Dry Pigment.—The pigment shall be made by suitable treatment 
of a mixture of precipitated zinc sulfide and precipitated barium sulfate. 

(b) Paste.—The paste shall be made by thoroughly grinding the specified 
pigment with pure raw or refined linseed oil. 


II. PROPERTIES AND TESTS. 


3. (@) The behavior on exposure to light, the mixing properties with an 
approved vehicle, the final consistency with this vehicle and the color shall 
be equal to, and the brightness and tinting strength (or hiding power) shall 
be not less than, those of a sample, mutually agreed on by buyer and seller. 

(b) Dry Pigment.—The dry pigment shall meet the following requirements: 


MAxIMUM MINIMUM 
Coarse particles and skins (total residue re- 


tained on a standard No. 325 screen), per 
ee ote Figs gis fein sect vives less a sv ees 1.0 


ty CS 0S) MTS | iene 26.0 
MO RICG SCT COUT. gcc. ct et ec cece wt tees 2.0 ht 
Material soluble in water, per cent............ 0.8 Satek 
RUMPNRINIEPEPOUTL TOTES toc, cte ns es ses ecw ccsccedicoces 98 per cent of the 
remainder. 


(c) Paste.—The paste as received shall not be caked in the container and 
shall break up readily in oil to form a smooth paint of brushing consistency. 
It shall mix readily in all proportions without curdling, with linseed. oil, 
turpentine, or volatile mineral spirits, or any combination of these sub- 
stances. The paste shall meet the following requirements: 


MAXIMUM MINIMUM 


SPIO T PCO itso so ives eae cde ae cee 80.0 76.0 
IS it) a re 24.0 20.0 
Coarse particles and skins (total residue re- 

tained on a standard No. 325 screen, based 

emmILG ) ACL. CONE. «cine sec sacs ee eee e's 1.5 


4. (a) Paste.—One sample shall be taken at random from each lot of 1000 
packages or less. If the packages are of such size that 1000 packages amount 
to more than a carload, one sample shall be taken at random from each 
earload. 

(b) Dry Pigment.—Dry pigment shall be sampled by taking a portion from 
every tenth barrel or from every one hundredth bag of the dry pigment. 


A. 8. T. M. TENTATIVE SPECIFICATIONS FOR 
TITANIUM BARIUM PIGMENT 


ISsuED, 1927. 


1. ‘lhese specifications cover titanium barium pigment in the dry form, 
also ground in oil to form a paste. 


. MANUFACTURE 
2. (a) Dry Pigment.—The pigment shall consist of titanium oxide precipi- 
tated upon and coalesced with blane fixe (precipitated barium sulfate). 


702 Analysis of White Pigments 
Le 

(b) Paste.—The paste shall be made by thoroughly grinding the pigment 
in pure raw or refined linseed oil. 


PROPERTIES AND TESTS 
3. (a) When specified, the color and color strength shall be equal to that 
of a sample mutually agreed upon by the buyer and seller. 
(b) Dry Pignent.—The pigment shall be thoroughly washed and shall 


conform to tue following requirements: 
MaxIMUM MINIMUM 


Coarse particles (total residue retained on a 


No. 325 screen*) per Cent........--+ee-ees 1.0 Pat 
Titanium oxide (TiO,), per cent.......-+-+++--: ook 24.0 
Total impurities, including moisture, per cent.. 1.0 oe 

remainder remainder 


Barium sulfate... 56. ve ces va sis 6 oo re ie oer 

(c) Paste—The paste as received shall not be caked in the container and 

shall break up readily in oil to form a smooth paint of brushing consistency. 

It shall mix readily in all proportions, without curdling, with linseed oil, 

turpentine or volatile mineral spirits, or any mixture of these substances. 
The paste shall conform to the following requirements : 


MAxIMUM MINIMUM 


Pigment, per Cent. .....-. ee ee rece eee eer eecece ee 80.0 — 
Linseed oil, per CeMt........---e eee eeeeeceees 20.0 Vite 
Moisture and other volatile matter, per cent... 0.7 
Coarse particles and “skins” (total residue re- 
tained on a No. 325 scree,* based on pig- 
ment), per Cent... 2... cere eereceeescess 1.5 
4. One sample shall be taken at random from each lot of 1000 packages 
or fraction thereof. If the packages are of such size that 1000 amount to 
more than a carload, one sample shall be taken at random from each carload. 


A.S. T. M. STANDARD METHODS OF ROUTINE ANALYSIS OF 
WHITE PIGMENTS 


I. METHOD FOR VERY SMALL AMOUNTS OF IRON. 

Lead Pigments.—Treat sample with HNO, (1:1) in usual manner, dilute 
with H,O, add H,SO, to precipitate bulk of lead (not necessary to evaporate 
down) ; cool, filter, wash with 1 to 2 per cent of H,SO:, make filtrate just 
alkaline with NH,OH, then just acid with dilute HNO,, determine iron colori- 
metrically by the thiocyanate method, using same amounts of reagents in 
preparing standards. If sample contains insoluble matter, filter out and 
wash with hot water till Pb-free, and to filtrate add H,SO, and proceed as 
given. The insoluble is ignited, treated with HF and H.SO, in usual manner, 
brought into solution (filter out any BaSO:), and added to filtrate from 
PbSO,. If necessary, solution may be made up to volume and aliquots taken. 
Copper, if present, shall be removed by precipitating the Fe with NH,OH, 
filtering, washing, redissolving Fe(OH), and proceeding as above. 

Other Pigments.—Treat as above, omitting the addition of H.SO,. 


Il GENERAL METHOD. 
True specific gravity shall be determined in accordance with the Standard 


* See footnote on page 697. 


a 


oy ee 


ae Se 


nS 
= 
:, 
a 
~ 
= 
* 
i 
2 
*. 
+ 
7 
= 
* 


_ Analysis of White Pigments 703 


Method of Test for Specific Gravity of Pigments (Serial Designation: D 153) 
of the American Society for Testing Materials. 


BASIC CARBONATE OF LEAD. 

Total Lead (Gravimetric).—Dissolve 1 B20 Coote LENG we 1) ina 
covered beaker, heating till all CO, is expelled; wash off cover, add 20 ce. of 
H,SO« (1 : 1) and evaporate to fumes of SO,, cool, add about 150 cc. of water 
and 150 ce. of ethyl alcohol; let stand in cold water 1 hour, filter on a 
Gooch crucible, wash with 95-per-cent ethyl alcohol, Ory ab ios Co and 
weigh PbSO,; calculate to PbO or to basic carbonate.* Instead of determin- 
ing the lead as sulfate, the sample may be dissolved by boiling with acetic 
acid; then dilute to about 200 ce. with water, make alkaline with NH,OH, 
then acid with acetic acid, heat to boiling and add 10 to 15 ce. of a 10-per-cent 
solution of potassium dichromate; heat till the yellow precipitate assumes 
an orange color. Let settle and filter on a Gooch crucible, washing by de- 
cantation with hot water till the washings are colorless finally transferring 
all of the precipitate. Then wash with 95-per-cent ethyl alcohol and then 
ether; dry at 110° C. and weigh PbCrOQ,. (Any insoluble matter should be 
filtered out before precipitating the lead.) 

Fotal Lead (Volumetric).—Dissolve 0.5 g. of sample in 10 ce. of concen- 
trated hydrochloric acid, boil till solution is effected, cool, dilute to 40 ce., 
neutralize with ammonium hydroxide. Add acetic acid until distinctly acid, 
dilute to 200 cc. with hot water, boil and titrate with ammonium molybdate 
as follows: 

Dissolve 4.25 g. of ammonium molybdate in water and make up to one 
liter. To standardize this solution, dissolve about 0.2 g. of pure lead foil in 
nitric acid (pure PbO or PbSO, may also be used), evaporate nearly to dry- 
ness, add 30 cc. of water, then 5 cc. H,SO, (sp. gr. 1.84), cool, and filter. 
Drop filter with PbSO, into a flask, add 10 ec. of concentrated HCl, boil till 
completely disintegrated, add 15 cc. of HCl, 25 cc. of water, and NH,OH till 
alkaline. Acidify with acetic acid, dilute to 200 cc. with hot water and boil. 
Titrate, using an outside indicator of one part of tannic acid in 300 parts 
of water. ; 

It should be noted that when calcium is present, it forms a more or less 
insoluble molybdate, and results are apt to be high. With samples containing 
less than 10 per cent of lead, the lead should be precipitated as PbSOs, filtered, 
redissolved and titrated as in the process of standardizing. 

Carbon Dioride.—Determine by evolution with dilute hydrochloric acid 
absorbing in soda-lime or KOH solution. Calculate CO, to PbCO,, subtract 
PbO equivalent from total PbO and calculate residual PbO to Pb(OH),. 

Acetic Acid.j—Place 18 g. of the pigment in a 500-cc flask, add 40 cc. of 
Sirupy phosphoric acid, 18 g. of zinc dust and 50 cc. of water. Connect to a 
Straight Liebig condenser, apply heat and distill down to a small bulk. Then 
pass steam into the flask until it becomes about half full of condensed water, 
Shut off the steam and distill down to a small bulk—this operation being con- 
ducted twice. To the total distillate which was collected in a larger flask 
add 1 ce. of sirupy phosphoric acid, connect to a Liebig condenser, using a 
Spray trap, and distill to a small volume—about 20 cc. Pass steam through 


*This method of weighing lead sulfate is not accurate in the presence of 
caleiuam compounds. 
+ Thompson’s Method, Journal, Soe. Chem. Ind., Vol. 24, p. 487 (1905). 


704 Analysis of White Pigments 


, ; 


till abeut 200 ec. of water condense in the distillation flask, shut off steam 
and continue the distillation. These operations of direct and steam distilla- 
tions are conducted until 10 cc. of the distillate require only one drop of 0.1 
N alkali to give a change in the presence of phenolphthalein. Then titrate 
the total distillate with 0.1 N sodium hydroxide and phenolphthalein and cal- 
culate the total acidity as acetic acid. It will be found convenient to titrate 
each 200-ce. portion of the distillate as collected. 

Metallic Lead.*—Weigh 50 g. of the sample into a 400-cc. beaker, add a 
little water and add slowly 60 ce. of 40-per-cent acetic acid and after efferves- 
cence has ceased, boil on hot plate. Fill the beaker with water, let settle, 
and decant the clear solution. To the residue add 100 ce. of a mixture of 
360 cc. of strong NH:OH, 1080 cc. of water, 2160 ce. of 80-per-cent acetic acid 
and boil until all solution is complete. Fill beaker with water, let settle and 
decant the clear solution. Collect residue on a watch glass, floating off every- 
thing but metallic lead. Dry and weigh. Result x 2= percentage of metallic 
lead in-sample. 

The following method of A. N. Finn (unpublished) gives total basicity 
of a pure white lead: Place 2 g. of pigment in an evolution flask, add a little 
CO,-free water, connect up to the separatory funnel and condenser (Knorr 
type), add through the funnel, finally washing down, 100 cc. of N /4 nitric 
acid, boil and absorb the CO, in soda-lime tube in usual manner (having 
H,SO, and CaCl, drying tubes in train) and weigh. To the solution in the 
evolution flask, add about 20 cc. of neutral sodium-suifate solution and titrate 
with N /4 sodium-hydroxide solution (carbonate-free), using phenalphthalein. 
CO, is calculated to PbCO,;. The amount of N /4 acid corresponding to the 
CO, is calculated and deducted from the total amount of N /4 acid neutralized 
by the sample and the difference calculated to combined H,O, from. which 
Pb(OH), is computed. 


Basic SuLFATE OF LEAD{ 

Determination of Total Lead.—Dissolve 1 g. of the sample in 100 ce. of 
a mixture consisting of 125 cc. of S80-per-cent acetic acid, 95 ec. of NHiOH 
(sp. gr. 0.90) and 100 cc. of water. Add the solution while hot and dilute 
with about 50 ce. of water, boil until sample is dissolved. Dilute to 200 ce. 
and titrate with standard ammonium-molybdate solution as described under 
basic carbonate of lead. The ammonium-molybdate solution contains about 
8.67 g. per liter and is standardized against pure lead foil, pure PbO or pure 
PbSOQ,. 

Determination of Total Zine.—Boil 1 g. of the sample with 30 ce. of water, 
4 g. of NH.Cl and 6 ec. of concentrated HCl (some PbSO, or PbCl, may not 
dissolve). Dilute to 200 cc. with hot water, add 2 ce. of a saturated solution 
of sodium thiosulfate and titrate with a standard solution of potassium ferro- 
evanide in usual manner. Calculate the zine to ZnO,t as follows: 


tIt would probably be more accurate to remove total lead as PbSO, and 
titrate the zinc in the filtrate after adding NH,OH and HCl in usual manner. 
99.10§—percentage of ZnO found = percentage of lead constituents ; 


* Thompson's Method, Journal, Soe. Chem. Ind., Vol. 24, p. 487 (1905). 
tJ. A. Schaffer’s Method, Journal of Industrial and Engineering Chemistry, 
Vol. 6, p. 200 (1914), may be used. 
{This figure (99.70) is the average total percentage of PbSO,, PbO and 
ZnO, found in 270 total analyses of basic lead sulfate. 


ae ee) f “ M 
at ey ee ee ee 


Analysis of White Pigments 705 


Then 
( At. wt.Pb. 


Mol. wt. PbSO, — mol. wt. PbO 
Mol. wt. PbO 


Mol. wt. PbO 
——_— X % Pbhfound } — % Pb constituents 
An wt, Pb. 


$$ = % PSO, present 
Mol. wt. PbO — Mol. wt. PbSO, 


Mol. wt. PbSO, 


Sulfur Dioxide.—Digest 2 g. of the sample with frequent stirring in 100 
ce, of freshly boiled cold water and 5d cc. of concentrated HCl; let stand 10 
to 15 minutes, add an excess of 0.01-normal iodine solution and titrate back 
with 0.01-normal sodium-thiosulphate solution, using starch indicator. Report 
as SO,. Run blank on reagents and make corrections. Or, the SO, may be 
titrated directly with iodine. 


oP b found ) — % Pb constituents 
= % PbO present 


Soluble Zinc Sulfate—Determine as under “Zinc-Lead and Leaded Zines.” 


ZINC-LEAD AND LEADED-ZINCS—OZLO WHITE 


Total Lead and Zinc.—Dissolve 1 g. of the sample by boiling with 250 ce. 
of water and 20 cc. of concentrated HNO,;, add 5 cc. of concentrated H,SO,, 
and evaporate to copious fumes of SO,; cool, add 250 cc. of water, let stand 
cold 1 to 2 hours, filter on Gooch crucible, wash with 1-per-cent H,SO,, ignite, © 
and weigh as PbSO,. Report as PbSO.. The PbSO, may be filtered on paper 
and then dissolved and titrated with ammonium-molybdate solution as de- 
scribed under basic carbonate of lead. Make filtrate from PbSOs« alkaline 
with NH,OH, then acid with HCl, add 3 ce. of concentrated HCl, heat to 
nearly boiling, and titrate the total zinc with potassium-ferrocyanide solution 
using uranium-acetate solution as an outside indicator and calculate to ZnO. 
(Iron, copper, or other interfering substances should first be removed as 
described by Low.) 

Sulfates other than Barium Sulfate—rTreat 0.5 g. of the sample with 5 cc. 
of water, 3 g. of NH,Cl and 5 ce. of HCl saturated with bromine; digest 
(covered) on steam bath about 15 minutes, add 25 ce. of water, neutralize 
with dry Na,CO,, and add about 2 g. more, boil 10 to 15 minutes; let settle, 
dilute with hot water, filter and wash with hot water; redissolve in HCl, 
reprecipitate as above and wash thoroughly with hot water; acidify united 
filtrates with HCl, adding a slight excess; boil and add slight excess of 10- 
per-cent barium-chloride solution. Let stand on steam bath 1 hour, filter, 
wash with hot water, ignite, and weigh BaSOs. Calculate to SO, (includes 
SO, formed from SO,). Of, dissolve 0.5 g. of the sample in 25 ce. of water, 
10 ce. of NH,OH (sp. gr. 0.90) and HCl in slight excess; dilute to about 150 
ce. with water and add a piece of aluminum foil which should about cover 
the bottom of the beaker—this held on bottom by means of a stirring rod. 
Heat gently till all lead is precipitated, decant through a filter, pressing the 
lead sponge with a flattened rod, and washing with hot water. Add to the 
filtrate a little pure bromine water, boil until bromine is expelled, add 15 ee. 
of 10-per-cent barium-chloride solution, lét stand on steam bath one hour, 


706 Analysis of White Pigments 


filter, wash with hot water, ignite and weigh as BaSO, (any SrSO.« present 
is not decomposed in this method) .* 

Soluble Zinc Sulfate.—Heat nearly to boiling 2 g. of the sample with 150 
ce. of water and 50 cc. of 95-per-cent alcohol for 30 minutes, filter, and wash 
with a mixture of alcohol and water (1:3). Heat filtrate to boiling and expel 
most of the alcohol; then determine SO, by usual method of precipitation 


~ 


Norn—lIf sample contains Ca or Mg, the Pb and Zn should be separated | 
by precipitation with H,S after dissolving in HCl, making alkaline with 
NH,OH and acid with acetic acid. The PbS+ZnS is dissolved in dilute HNO, 
and the Pb and Zn determined as above. ; 


Sulfur Dioxide——Determine as under “Basic Sulfate of Lead” or “Zine 
Oxide.” 


ZINC OXIDE. 


Total Zinc-—Dissolve 0.25 to 0.8 g. in 10 ce. of concentrated HCl and 20 
ec. of H,O, make alkaline with NH,OH, then acid with HCl, add 3 cc. more 
of concentrated HCl, dilute to about 250 cc. with H,O, heat nearly to boiling 
and titrate with standard potassium-ferrocyanide solution as described by 
Low.+ Report as ZnO (includes Cd). Iron, copper or other interferring 
substances should be first removed as described by Low. 

Total Soluble Sulfur.s—Moisten a 10-g. sample with water, add a few — 
drops of bromine and then concentrated HCl, boil to expel bromine, filter — 
from any insoluble and wash with hot water. Make alkaline with NH.O8, ~ 
then just slightly acid with HCl, heat to boiling and add about 15 ce. of hot ~ 
barium-chloride solution. Let stand several hours (over night), filter on a 
weighed Gooch crucible, wash well with hot water, dry, ignite for five minutes, ~ 
cool and weigh as BaSO,. Calculate to 8. og 

Sulfur Dioxide.2—Mix 5 g. of sample with 50 cc. of warm (freshly boiled — 
and then partly cooled) water to an emulsion and pour into a glass-stoppered — 
flask containing 18 ec. of HCl and exactly 25 ce. of 0.1-normal iodine solution, 
stopper and shake until all the oxide is dissolved. Titrate the excess of © 
iodine as rapidly as possible with 0.1-normal sodium-thiosulfate solution, — 
Caleulate to SO,. 

Soluble Zine Sulfate-——Determine as under “Zinc-Lead and Leaded-Zines.” — 


LITHOPONE 
PONOLITH, JERSEY LILY WHITE, BECKTON WHITE, CHARLTON 
WHITE, ORR’S WHITE. 


Insoluble and Total Zine.—Take 1 g. of the sample in a 200-ec. beaker, — 
add 10 ce. of concentrated HCl, mix, and add in small portions about 1 g. : 
of KCIO,, then heat on the steam bath until about half of the liquid is evapo-— 
rated. Dilute with H,O, add 5 ce. of dilute H,SO, (1:10); boil, let settle, © 


filter, wash, ignite, cool, and weigh the insoluble which should be only BaSO4;_ 
make a qualitative examination for alumina and silica. The insoluble 


should be examined under the microscope for the presence of natural erystal- 


* The solubility of BaSO, is increased by the presence of aluminum chloride. — 

See J. W. Mellor, “A Treatise on Quantitative Inorganic Analysis,” p. 615. 
+ Low, “Technical Methods of Ore Analysis.” . 
x Method of G. Rigg. 


Analysis of White Pigments 707 
a em a le mee 


lin barytes. Sample may also be examined direct. Make filtrate from in- 
soluble alkaline with NH,OH, acid with HCl, add 3 ce. of concentrated HCl, 
dilute to about 250 cc. with H,O, heat nearly to boiling and titrate with 
K,Fe(CN), solution as under zine white. Calculate to Zn. 

Zinc Oxride.—Treat a 4-g. sample of the lithopone for 4 hours with 200 ce. 
of 1-per-cent acetic acid at room temperature, stirring occasionally. Filter 
’ by suction on a double filter paper and wash with cold water; add to the 
elear filtrate 13 cc. of concentrated NH:OH, neutralize with HCl and then 
add 3 ce. of concentrated HCl in excess. Heat to boiling and. titrate with 
K,Fe(CN),, using uranium-acetate solution as an outside indicator. Calculate 
to ZnO. Calculate this result to Zn, subtract from total “n, and calculate the 
difference to ZnS. (Any ZnCO, or ZnSO, is included in the ZnO.) 

Zine Sulfide.*—Place 0.5 g. of pigment in evolution flask with about 10 g. 
of “feathered” or mossy zinc, add 50 ce. of water; insert the stopper carrying 
a separatory funnel and an exit tube. Run in 50 ce. of concentrated HCl 
from the funnel, having previously connected the exit tube to two absorption 
flasks in series; first flask contains 100 ce. of alkaline lead-nitrate solution, 
second flask, 50 cc. of same as a safety device. After all of the acid has run 
into the evolution flask, heat slowly, finally boiling until the first appearance 
of steam in the first absorption flask; disconnect, let the lead sulfide settle, 
filter, wash with cold water, then with hot water till neutral to litmus paper 
and washings give no test for lead. The PbS precipitate is dissolved in hot, 
dilute HNOs, evaporated to fumes with H»SO, and finally weighed as PbSO4. 
Calculate PbS or PbSO, to ZnS. 

The alkaline lead solution is made as follows: Into 100 ee. of KOH solu-- 
tion (56 g. in 140 cc. of H,O) pour a saturated solution of lead nitrate (250 
g. in 500 cc. of H,O) until the precipitate ceases to redissolve, stirring con- 
Stantly while mixing. About 3 volumes of the lead solution will be required 
for one of the alkali. 

Instead of absorbing the evolved H.S in alkaline lead-nitrate solution, a 
Solution of 8 g. of cadmium chloride in 250 ec. of water and 150 ce. of NH,OH 
(sp. gr. 0.90) may be used. The CdS precipitate may be filtered on a weighed 
Gooch, washed with water containing a little NH,OH, dried at 100° C., and 
weighed. Calculate to ZnS. It is better to filter the CdS on a Small filter 
and wash as above, then place filter and precipitate in a beaker and dissolve 
in HCl and KCIO, (keeping at room temperature at first), filter out any 
paper pulp or insoluble matter; make filtrate alkaline with NH,OH, then just 
acid with HCl, heat to boiling and precipitate with BaCl, in usual manner. 
Filter, wash, ignite, and weigh BaSO, Calculate to ZnS. 

For very rapid work the contents of the absorption flask, after all H.S 
has been absorbed, may be washed into a vessel with cold water and diluted 
to about one liter, acidified with concentrated HCl and titrated with standard 
iodine solution, using starch indicator. (The precipitate should be completely 
dissolved.) The iodine solution is prepared by dissolving about 12.7 g. of 
pure resublimed iodine and 18 g. of KI in a little water and then diluting 
to one liter. 


— 


* Kvolution Method of W. G. Scott, “White Paints and Painting Material,” 
Dp. 257; see also Blair, “Chemical Analysis of Iron.” 


708 Analysis of White Pigments 


CALCIUM PIGMENTS 
WHITING, PARIS WHITH, SPANISH WHITE, AND CHALK. 

Make a qualitative examination first; should contain only small amounts 
of insoluble matter (siliceous), iron, aluminum, sulfur, water or magnesium, 
and should be approximately 95 per cent CaCQ,. 

Total Soluble Lime.*—Weigh out 0.75 g. of the pigment into a small cruci- 
ble, ignite cautiously to dull redness to destroy organic matter, cool, transfer 
to a 400-ce. beaker, add 20 cc. of H,O, cover, then add 15 ce. of concentrated 
HCl and: 3 or 4 drops of concentrated HNO,, and boil till all the soluble matter 
is dissolved and all the CO, expelled. Wash off and remove the cover, dilute 
to about 150 ce. with freshly boiled H,O, heat to boiling and add dilute NH,OH 
(sp. gr. 0.96) carefully until a slight permanent precipitate forms. Heat to 
boiling and add 10 ce. of a 10-per-cent solution of oxalic acid; stir until the 
oxides of iron and aluminum are entirely dissolved and only a slight precipi- 
tate of calcium oxalate remains. Now add 200 ec. of boiling H,O and suffi- 
cient saturated solution of ammonium oxalate (20 to 25 ce.) to precipitate 
the lime. Boil and stir for a few moments, remove from the heat, let settle 
and filter on an 11-cm. filter. Wash 10 times with 10-to-15-ce. portions of 
hot water. Place beaker in which precipitation was made under the funnel, 


pierce apex of filter with stirring rod and wash precipitate into beaker with — 


hot water, pour warm dilute H,SO, (1:4) through paper and wash a few 
times; add about 30 ce. of the dilute with H,SO,4 (1:4), dilute to about Za CC, 
heat to 90° C. and titrate at once with standard KMnO, solution (solution 


should not be below 60° C. when end-point is reached). The KMnOy, is best | 


standardized against Bureau of Standards sodium oxalate.t Calculate to 
CaO and CaCQ,. 

Mixed Calcium and Magnesium Carbonate.z—Weigh 1 g. of the finely 
powdered sample into a small porcelain dish, add 25 ce. of normal HCl, cover 
with a watch glass, and when effervescence has ceased, heat to boiling. Cool 
and titrate with normal NaOH solution, using methyl orange as indicator, 

The calculation is as follows: 


One gram CaO = 385.7 ce. of normal acid. CaO 1.784 == CaCG, “Sub : 


tract number of cubic centimeters of NaOH required from 25, result gives 
number of cubic centimeters of normal acid corresponding to the CaCO, ++ 
MgCoO,. Multiply the weight of CaO in 1 g. of sample (as found in preceding 
section on total soluble lime) by 35.7; product gives number of cubic centi- 
meters of normal acid corresponding to the CaO present; subtract from total 
number of cubic centimeters of acid required by CaCO, + MegCO, and multiply 


result by 0.42, obtaining weight of MgCO, in 1 g. of sample. The MgCoO, — 


determined by this process should not differ more than 0.25 per cent from 
that obtained by more elaborate methods. It is to be noted that this method 
is a measure of the total alkalinity, and if Ca or Mg are present in other 


forms than carbonate, a complete analysis would be necessary to give per-— 


centages of CaCO, and MgCO,. 


Instead of the above, Newberry’s] method for the simultaneous determina- | 


tion of calcium and magnesium carbonates may be used. 


* Meade, “Portland Cement.” 
+ Circular No, 40, Bureau of Standards. 
+ J. W. Mellor, “A Treatise on Quantitative Inorganic Analysis,” p. 522. 


§, Meade, “Portland Cement ;” Mellor, “A Treatise on Quantitative Inorganic 
Analysis,” p. 522; Cement Engineering News, Vol. 15 Dp. 35 (1903). 


2 
7 


® 


Analysis of White Pigments 709 


GYPSUM, TERRA ALBA, PLASTER OF PARIS 

Combined Water and Moisture—Heat 1 g. of the sample in a covered 
porcelain crucible on an asbestos plate for 15 minutes, then heat bottom 
of crucible dull red for 10 minutes over a Bunsen burner, remove cover and 
heat for 30 to 40 minutes at a slightly lower temperature. Cool and weigh 
rapidly. Repeat to constant weight. 

Combined water and moisture may also be determined by heating in an 
air bath at 200° C. to constant weight. 

Insoluble Matter.—Boil 2 to 3 g. of the sample with 20 cc. of concentrated 
1iCl, a few drops of HNO;, and about 50 ce. of water; evaporate to dryness, 
boil residue repeatedly with 10-per-cent HCl, decanting through a filter; 
finally transfer to the filter, wash with hot water, ignite and weigh insoluble 
matter; test for BaSO,. Make a qualitative examination of the filtrate from 
the insoluble matter to determine if Al, Fe, or Mg are present in abnormal 
amounts (should be mainly Ca and SO,). Test a separate portion of the 
sample for CO.; if desired determine as under “Basic Carbonate of Lead.” 


BARIUM PIGMENTS 
BARYTES OR BARITE, ‘“‘BLANC FIXE” 

Examine the sample microscopically to determine uniformity of grinding, 
size and angularity of particles, crystallin or amorphous. The sample should 
be at least 95 per cent BaSQ,. 

Loss on Ignition.—Ignite 1 g. of the sample for 30 minutes. Loss may. 
be due to organic matter, moisture, combined water and CO, (and SO, from 
CaSO, if present). If loss is appreciable, test for CO,. 

Soluble and Insoluble Matter.—Boil 1 g. with HCl (1:3), filter, wash with 
hot water, ignite, and weigh insoluble matter. This may be treated with 
H.SO, and HF in usual manner for SiO, In the absence of <Al,O, (from 
silicates) residue is considered as BaSO,. Make qualitative tests of filtrate 
from the insoluble for Al, Fe, Ca, Mg, SO,;. Test a separate portion of 
sample qualitatively for CO.. 


SILICA PIGMENTS 
SILICA OR SILEX 
Silica or silex should be practically pure SiO, <A qualitative examina- 
tion will suffice in most cases with a determination of the loss on treating 
1 g. of sample with H,SO,4 and HF in usual manner. 


CHINA CLAY AND ASBESTINE 

A qualitative analysis of China clay to determine if essentially hydrous 
aluminum silicate is generally all of the chemical tests necessary. Color, 
fineness, etc., are more important than analysis. 

Asbestine is tested qualitatively to prove that material is as represented. 
Color, fineness, etc., are important. Asbestine should be examined under the 
microscope to note whether it is fibrous or taleose and whether silica or 
China clay are admixed. Samples of known origin should be used here as a 
guide for comparison. 


710 Analysis of White Pigments 


A. S.T. M- STANDARD METHODS OF ROUTINE ANALYSIS OF 


TITANIUM PIGMENTS 
GENERAL METHODS 
SPECIFIC GRAVITY 


1. True specific gravity shall be determined in accordance with the Stand- 
ard Method of Test for Specific Gravity of Pigments (Serial Designation: 
D 153) of the American Society for Testing Materials.” 


COLOR 


2. To 5 g. of the sample add 1.5 cc. of linseed oil, rub on a stone slab or 
glass plate with a flat-bottomed glass or stone pestle or muller to a uniform 


paiey 


smooth paste. Treat in a similar manner 5 g. of the standard titanium ~ 


pigment. Spread the two pastes side by side on a clear, colorless glass 
plate and compare the colors. If the sample is as white as, or whiter than, 
the “standard,” it passes this test . 


CoLoR STRENGTH 
3. Weigh accurately 0.01 g. of lampblack, place on a large glass plate 
or stone slab, add 0.2 cc. of linseed oil and rub up with a flat-bottomed glass 
pestle or muller, then add exactly 10 g. of the sample and 2.5 ce. of linseed 


oil, and grind wth a circular motion of the pestle or muller 50 times ; gather | 


up with a sharp-edged spatula and grind out twice more in a like manner, : 


giving the pestle or muller a uniform pressure. Treat another 0.01 g. of 


lampblack in the same manner except that 10 g. of standard pigment is — 
used instead of the 10 g. of the sample. Spread the two pastes side by side 2 
on a glass microscope slide and compare the colors. If the sample is as light = 


or lighter in color than the “standard” it passes this test. 


COARSE PARTICLES 


4. Determine coarse particles in accordance with the Standard Methods j 
of Test for Coarse Particles in Paint Pigments (Serial Designation: D 185) — 


of the American Society for Testing Materials. 


METHODS OF ANALYSIS 
QUALITATIVE ANALYSIS 


5. Place about 0.5 g. of the sample in a 250-cc. Pyrex glass beaker ; add | 


20 cc. of concentrated H.SO, and 7 to 8 g. of (NH,).SO, Mix well and © 
boil for a few minutes. The sample should go completely into solution; a — 


residue denotes the presence of silica or siliceous matter. Cool the solution, — 
dilute with 100 ce. of water, heat to boiling, let settle, filter, wash with hot — 
5-per-cent H.SO, until free from titanium, and test the residue for lead, ete. — 
Test the filtrate for calcium, zine, iron, chromium, ete., by the regular methods eS 
of qualitative analysis. For the iron determination add to a portion of the © 
filtrate 5 g. of tartaric acid, render slightly ammoniacal, pass in H,S in excess, — 
and digest at side of steam bath for a while. No precipitate indicates the $ 


absence of iron, ‘nickel, cobalt, lead, copper, ete. A black precipitate readily — 


soluble in dilute HCl denotes iron. For titanium, test a small portion of the . 


original filtrate with hydrogen peroxide (a clear yellow-orange color should — 
result) and another portion with metallic tin or zine (a pale blue to violet 


Analysis of White Pigments 711 


coloration should result). Negative tests should be shown for sulfide sulfur, 
carbonates, and appreciable water-soluble matter. 


MOISTURE 
6. Place 1 g. of the sample in a wide-mouthed short weighing tube provided 
with a glass stopper. Heat with stopper removed for two hours at a tempera- 
ture between 105 and 110° C. Insert stopper, cool, and weigh. The loss in 
weight is reported as moisture. 


MATTER SOLUBLE IN WATER 
7. Transfer 2.5 g. of the pigment to a graduated 250-cc. flask, add 100 ce. 
of ‘water, boil for 5 minutes, cool, fill to mark with water, mix, and allow to 
settle. Pour the supernatant liquid through a dry filter paper and discard the 
first 20 cc. Then evaporate 100 cc. of the clear filtrate to dryness in a 
weighed dish, heat for one hour at 105 to 110° C., cool and weigh. 


TITANIUM OXIDE 

8. Transfer 0.5 g. of the dried sample to a 250-cc. Pyrex beaker, add 20 ce. 
of concentrated H,SO, and 7 to 8 g. of ammonium sulfate. Mix well and 
heat on hot plate until fumes of sulfuric acid are evolved, and then continue 
the heating over a strong flame until solution is complete (usually requires 
not over five minutes of boiling) or it is apparent that the residue is composed 
of silica or siliceous matter. Caution should be observed in visually examin- 
ing this hot solution. Cool the solution, dilute with 100 cc. of water, stir, heat 
carefully to boiling while stirring, let settle, filter through paper and transfer 
the precipitate completely to the paper. Wash the insoluble residue with cold © 
5-per-cent (by volume) H.SO, until titanium is removed. 

Dilute the filtrate to 200 cc. and add about 10 cc. of NH,OH (sp. gr. 0.90) 
to lower the acidity to approximately 5-per-cent H.SO, (by volume). 

Wash out a Jones reductor* with dilute 5 per cent by volume H,SO; and 
water, leaving sufficient water in the reductor to fill to the upper level of the 
zinc. (These washings should require not more than one or two drops of 
0.1 N KMnO, solution to obtain a pink color.) Empty the receiver, and put 
in it 25 cc. (measured in a graduate) of ferric sulfate solution (see Re- 
agents). Reduce the prepared titanium solution as follows :+ 

(1) Run 50 cc. of the 5-per-cent H.SO, solution through the reductor at 
a speed of about 100 cc. per minute. 

(2) Follow this with the titanium solution. 

(3) Wash out with 100 cc. of 5 per cent H.SO,. 

(4) Finally run through about 100 cc. of water. Care should be taken 
that the reductor is always filled with solution or water to the upper level 
of the zinc. Gradually release the suction, wash thoroughly the glass tube 
that was immersed in the ferric sulfate solution, remove the receiver, and 
titrate immediately with 0.1 N KMnO, solution. One ce. of 0.1 N KMn0O, 
equals 0.00481 g. Ti or 0.008 g. TiO, Run a blank determination, using the 


* Directions for preparing a Jones reductor may be found in Blair, “The 
Chemical Analysis of Iron,” Eighth Edition, pp. 88-89, or Treadwell-Hall, 
“Analytical Chemistry,” Vol. 2, Fifth Edition. 

7 Lundell and Knowles, “The Determination of Titanium by Reduction 
with Zine and Titration with Permanganate,” Journal, Am. Chemical Soc, 
Vol. 45, p. 2620 (1923). 


Viz Analysis of White Pigments 


aS 


same reagents, washing the reductor as in the above determination. Subtract 
this permanganate reading from the original reading and calculate the final 
reading to titanium dioxide (TiO.). This will include iron, chromium, arsenic, 
and any other substance which is reduced by zine and acid. See Calculations 
below for reporting TiO,. 


BARIUM SULFATE 
9. Ignite, cool, and weigh the precipitate of BaSO, obtained in separating — 
the titanium in Section 8. . 


Note.—If sample is impure it may be necessary to purify this precipitate, 
using appropriate methods. 


IRON OXIDE. 

10. Prepare a standard ferric solution containing 0.00001 g. of Fe per 
cubic centimeter (see Reagents). Weigh a 1-g. portion of the sample and 
treat as in Section 8. Transfer without filtering to a graduated 200-cc. flask, 
cool, fill to the mark with water, mix, let settle, and determine iron colori- 
metrically as follows: Filter through a dry filter paper, discarding the first 
20 ce.; transfer 50 ce. of the clear filtrate to a clean 100-ce. Nessler tube or 
other comparator. Add a drop or two of 0.1 N KMn0O, solution to oxidize 
any ferrous iron. The faint pink color should persist for at least 5 minutes. 
Add 10 ec. of KCNS or (NH,)CNS solution (see Reagents), dilute with water © 
to 100 ce., and mix thoroughly. Compare the color immediately with a series 
of standards, prepared side by side with the sample, in similar tubes. Pre- 
pare the standards from the standard ferric solution so as to have a range 
of from 0.000005 g. Fe to 0.00004 g. Fe (0.5 to 4.0 ce.). Transfer the desired 
volumes of the standard ferric solution to 100-cc, Nessler tubes containing 50 — 
ec. each of an acid solution (made up by dissolving 8 g. of (NH,).SO, in water, 
adding 20 ce. of concentrated H,SO,, cooling, diluting with water to 200 cc., 
and mixing), add a drop of 0.1 N KMn0O, solution (or sufficient to yield a = 
pink color that will persist for 5 minutes), and then 10 cc. of the thiocyanate i 
solution. Finally dilute all standards with water to 100 cc. and mix each 
thoroughly. 


Nore.—For a single sample it is more convenient to run the standard Fe 
solution from a burette into a Nessler tube, containing 50 ce. of acid solution 
(made by dissolving 8 g. of (NH,).SO, in water, adding 20 cc. of concentrated 
H,SO,, cooling and diluting with water to 200 ce., and mixing), a drop of 0.1 NV 
KMn0O, solution, 10 cc. of the thiocyanate solution, and then dilute with dis- 
tilled water until the depth of the color produced after diluting 100 cc. and — 
mixing, exactly matches that of the sample. From the burette réading ealcu- 
late the amount of Fe. When using standards, the color comparisons must be — 
made immediately. 


CALCULATIONS i 

11. Caleulate the total iron found to Fe.O, and report as such. Calculate — 
the TiO, equivalent by multiplying the Fe.O, result by the factor 1.003 and — 
subtract this figure from the total TiO, as determined in Section 8 and report 
the remainder as TiO.. . 


Report all results on the dry or moisture-free basis. 
SOLUTION REQUIRED : 
12. Decinormal Potassium Permanganate Solution.—Dissolve 3.2 g. of pure — 


KMn0Q, in 1 liter of distilled water, let stand 8 to 14 days, siphon off the clear — 


Analysis of White Pigments 713 


solution (or filter through asbestos), and standardize as follows: In a 400-ce. 
beaker dissolve 0.25 to 0.30 g. (accurately weighed) of U. S. Bureau of Stand- 
ards’ sodium oxalate in 250 ce. of hot water (80 to 90°C.) and add 15 ce. 
of dilute H,SO, (1:1). Titrate at once with the KMn0O, solution, stirring 
the liquid vigorously and continuously. The KMnO, must not be added more 
rapidly than 10 to 15 ce. per minute, and the last 0.5 to 1 cc. must be added 
dropwise with particular care to allow each drop to be fully decolorized before 
the next is introduced. The solution should not be below 60° C. by the time 
the end point is reached. (More rapid cooling may be prevented by allowing 
the beaker to stand on a small asbestos-covered hot plate during the titration. 
The use of a small thermometer as a stirring rod is most convenient.) ‘I'he 
weight of sodium oxalate used multiplied by 0.833 gives its iron equivalent, 
or multiplied by 1.195 gives its titanium dioxide equivalent. The KMnQ, 
solution should be kept in a glass-stoppered bottle painted black to keep out 
light. 


Ferric Sulfate Sclution for Titanium.—A solution containing 2 per cent of 
iron as ferric sulfate is desired and may be prepared as follows: Dissolve 
20 g. of pure iron or plain carbon steel in a slight excess of HCl, oxidize with 
HNO,, add about 80 ec. of H.SO, and heat until fumes of the latter are evolved. 
Cool, dilute with water to 1000 ec., digest on a steam bath until sulfates are 
dissolved, and filter if necessdry. Add 0.1 N KMn0O, solution until a faint 
pink color persists for 5 minutes (to oxidize any ferrous iron that may be 
present). 

Ferric ammonium sulfate may be used also.* 

Standard Ferric Sulfate Solution for Colorimetric Determination of Iron.— 
Determine the strength of the ferric solution for the TiO, determination in 
terms of Fe and dilute a portion of this solution until one is obtained of the 
strength 1 ec. equals 0.00001 g. Fe. 


Potassium Thiocyanate Indicator.—Prepare a 2-per-cent solution of the 
pure salt in distilled water. 


Carbon Dioxide Test on White Pigments.—A simple and 
efficacious method of determining carbonic acid in white pig- 
ments, which has been used in this laboratory, will be found 
below. 


The method can be used in such cases where the substances 
to be analyzed evolve gases other than carbon dioxide; that is, 
hydrogen sulphide, sulphur dioxide, or organic matter. The 
apparatus used is shown in Fig. 226. A weighed sample of 
the substance is introduced into the Erlenmeyer flask (A). 
Into flask (B) is placed a 10 per cent solution of barium chlor- 
ide, more than sufficient to hold the carbon dioxide evolved, 
and 20 ce. of concentrated ammonium hydroxide free from 
carbon dioxide. If sulphides are present, it is sometimes ad- 
visable to pass the liberated gas first through a few cc. of 


* Gooch, “Methods in Chemical Analysis,” First Edition, p. 436. 


714 Analysis of White Pigments 


strong potassium permanganate. The flask (B) is warmed 
until completely filled with ammonia fumes. Flask (C) is a 
safety bottle containing the same solution as flask (B). Only 
in rare cases will any trace of the carbon dioxide be noticed — 
in the safety flask. After flask (B) is completely filled with — 
ammonia vapor, make all connections and allow the hydro- ~ 
chloric acid to drop slowly from the separatory funnel into — 
the decomposition flask (A). When effervescence has ceased, 
heat the contents of the flask until filled with steam. The de- — 


FIGURE 226 


Carbon Dioxide Apparatus 


livery tubes and sides of the precipitating flask are then 
washed with boiling water, the flask is filled to the neck, stop- — 
pered, and the precipitated barium carbonate allowed to settle. 
Wash thoroughly by decantation, each time stoppering the 
flask to prevent any error from the carbon dioxide present in 
the air, and determine either gravimetrically, by conversion 
into barium sulphate, or volumetrically, by dissolving in stand- 


Analysis of White Pigments jh) 


ard hydrochloric acid and titrating the excess of acid used with 
standard potassium hydroxide. Calculate the barium found 
to carbonate and the amount of carbon dioxide from the found 
earbonate. The entire operation may be hastened by conduct- 
ing a brisk current of air free from carbon dioxide through 
the entire apparatus. 


Jamieson Determination of Zinc.*—The zinc is obtained in 
an HCl or HeSO, solution of not more than 5 per cent HCl. 
The solution is made up to 100 ee. and an aliquot containing 
not more than 0.10 gm. ZnO taken. If the volume taken ex- 
ceeds 35-ce., it should be concentrated to that amount. Add 
without stirring 25 ec. of the precipitating reagent, which 
consists of 19.5 grams potassium thiocyanate and 13.5 grams 
mereuric chloride in 500 ce. distilled water. Filter onto a 
tarred gooch and wash with a solution containing 10 ee. of the 
precipitating reagent in 500 cc. of water. Dry for one hour 
at 102-107° C. and weigh. The precipitate is ZnHg (SCN),. 
HO but becomes on heating at the above temperature ZnHg 


(SCN),. 


Factors 
ZnHg(SCN), to Zn, Multiply by 0.1312 
ZnHg(SCN), to ZnO, Multiply by 0.1632 
ZnHe(SCN), to ZnS, Multiply by 0.1954 


The following interfere: cadmium, cobalt, copper, bismuth, 
manganese, and mercurous compounds. Lead, if present, may 
be first removed by adding sulphuric acid to the solution be- 
fore making it up to volume. If appreciable amounts of ferric 
compounds are present, they may be reduced with sulphur 
dioxide, otherwise some ferric thiocyanate may be carried 
down with the zine precipitate. Nickel in small amounts does 
not interfere. 7 


Volumetric Method.*—If desired instead of filtering on a 
gooch as referred to in the first paragraph, the precipitate 
may be collected on a small paper in a Hirsch funnel and, after 
washing, transferred with the paper to an iodine titration 
bottle. A thoroughly cooled mixture of 35 ce. of HCl, 10 ee. 
against a standard solution of potassium iodate containing 


=G. $8. Jamieson, Ie Sache a bea th atey, (1918), Volumetric Iodate Methods, 
Chem. Cat. Co., p. 86 


716 Analysis of White Pigments 


39.2882 erams per liter, 1 cc. of which is equivalent to 0.0020 — 
erams zine. 

During the first part of the titration, the potassium iodate — 
solution is added rapidly while rotating the bottle in order to ~ 
keep the contents mixed. When the iodine which is liberated ~ 
during the first stage of the reaction has disappeared from the ~ 
solution, the stopper is inserted and the contents of the bottle — 
are thoroughly mixed by shaking for about half a minute. — 
From this point the titration is continued slowly, shaking the ~ 
closed bottle thoroughly after each addition of potassium 
iodate until the iodine color has disappeared from the chloro- — 
form indicator which marks the end point. If more than 50 ~ 
ec. of the potassium iodate solution is required for a titration, 
10 to 15 ee. more of hydrochloric acid should be added before — 
continuing the titration, in order to prevent the hydrolysis ‘ 
of the iodine monochloride. 


Inside Indicator in Zinc Titration.—In place of uranyl ni- 
trate which is used as an outside indicator in zinc titrations, 
diphenyl benzidine may be used as an inside indicator. ‘This 
method which was described by Cone and Cady, J. Am. Chem. ~ 
Soe. 49, 356-40(1927), conducts the titration in a sulphuric acid 
solution with the ferrocyanide solution containing 0.3 g. of © 
potassium ferricyanide per liter. The change in color is © 
from purple to pale green. 2 

Mixed Calcium Pigments.—In the above A. S. T. M. Meth- — 
ods, the analysis of mixtures of calcium carbonate and mag- — 
nesium carbonate are referred to. Among other mixtures — 


which might be present are calcium carbonate and calcium — 


sulfate. In the analysis of paints containing such mixtures, — 
carbon dioxide or sulphur trioxide should be determined, and ~ 
the calcium oxide equivalent calculated. The other component 
may then be calculated from the residual calcium oxide. ; 
Calcium Compounds in Titanium Pigments—Calcium ti- — 
tanium pigments sometimes contain calcium phosphate or — 
other calcium compounds. Heat carefully 1 gram of the pig- — 
ment with dilute HCl. Filter and wash. Remove the lead © 


with H.S. Boil the filtrate from the lead determination to — 


remove the H2S, neutralize, add 1 ce. of HNOs, then ammonium ~ 
acetate solution and acetic acid. Boil, and filter off the basic — 
ferric acetate. Any zinc may be removed from the filtrate 
with H2S and determined as on page 715. Boil the sR to ; 


Analysis of White Pigments 717 


remove H2S and determine the calcium as oxalate as described 
on page 708. 


CaO X 1.84 = Cas(PO,)2 


Phosphates.—Boil 1 gram of the pigment with HNO; (1:1). 
Filter and determine the phosphoric acid in the filtrate by the 
phospho-molybdic method. 


CHAPTER XL 


_ ANALYSIS OF LEAD OXIDES 


There are given below the A. 8. T. M. Standard specifica- — 
tions for red lead, and methods of analysis. Following these © 


specifications are presented some special methods for deter- 


mining red lead, as used in factories where these pigments are 


produced. There are also included special methods for de- 


termining such impurities as copper, iron, and free silica in ~ 


red lead. 
A. 8S. IT. M. STANDARD SPECIFICATIONS FOR 
RED LEAD | 

1. These specifications cover red lead to be used as a pigment, purchased i 
in the form of dry pigment or ground in oil to form a paste. $ 
I. MANUFACTURE . 
2. (a) Dry Pigment.—The pigment shall be made by roasting litharge or 
lead, or compounds of lead which yield litharge by heating. 3 
(v) Paste.—The paste shall be made by thoroughly grinding the specified Fa 
pigment in pure raw or refined linseed oil. % 
Nore.—Avoid storing red lead paste in places of high temperature, as heat : 
accelerates the tendency of this material to cake or harden. z 
Purchasers are cautioned not to buy red lead in paste form unless it is to 
be used within three months after shipment by the contractor. @ 
II. PROPERTIES AND TESTS x 
3. (a) Dry pigment shall consist entirely of oxides of lead, free from all : 
adulterants and shall conform to the following requirements: a 
85-Per-Cent 95-PeR-CENT 
GRADE GRADE ; 
True red lead, Pb,O,, minimum, per cent...... 85.0 95.0 2 
Total impurities, including moisture, soluble 7 
matter, water, and matter insoluble in a ¥ 
mixture of nitric acid and hydrogen per- 3 
oxide, maximum, per Cent.........++se+-=- 1.0 1.0 3 
a 
85-PeR-CeENT 95-Per-CENT 
GRADE GRADE $e 
The remainder shall be lead monoxide (PbO if 
Coarse particles retained on a Standard No, a 
325 screen, maximum, per cent...........-- 2:0 1.0 é 
When mixed with raw linseed oil, turpentine and liquid drier, in the ~ 
proportions : # 
Dry red lead... ...e0c. scenes tess 0 sa bee 0 5 Mion re 20° Ib. bs 
Raw linseed ofl... son. g seq cols sot © oipieis «isin m kely ean 5 pt. = 
Turpentine ....06sse sew cce wens nes © ose olemtns a ne 2 gills x 
Liquid. drier... ccs cece ce eens e ohie wn ae gee 2° e* S: 


an ‘ : is 


ay 


Se 


Analysis of Lead Oxides 719 
enna lr ee ad 


the resulting paint, when brushed on a smooth vertical iron surface, shall 
dry hard and elastic without running, streaking or sagging. 

(b) .Paste.—The paste as shipped by the contractor, and for three months 
thereafter, shall not be caked in the container and shall readily break up in 
oil to form a smooth paint of brushing consistency. The paste shall have the 
following composition: 


MAXIMUM MINIMUM 
uMEMP ICT CONG I 4 50) Poco. Soe kee Cele edna 94.0 92.0 
Semele Der Gent. 5 oo... sc ce veces. 8.0 6.0 


Moisture and other volatile matter, per cent... 0.5 

Coarse particles and skins (total residue re- 
tained on a Standard No. 325 sereen, based 
Mere rcne WeVerreent. sia. ace oko se has ee 1.5 


When mixed with raw linseed oil, turpentine and liquid drier in the fol- 
lowing proportions: 


Ty SEES GA ie et ek a gee en 20 Ib. 
NM et Teer ei ne, oh. ee 43 pt. 
(TONNES nce TADEN ci gs a 2 gills 


Liquid drier 2 N 
the resulting paint, when brushed on a smooth vertical iron surface, shall 
dry hard and elastic without running, streaking or sagging. 

4. One sample shall be taken at random from each lot of 1000 packages 
or less. If the packages are of such size that 1000 packages amount to more 
than a carload, one sample shall be taken at random from each ecarload. 


A.S. T. M. STANDARD METHODS OF ROUTINE ANALYSIS OF 
DRY RED LEAD 
1. The approximate formula of Red Lead is Pb,O, (probably PbO..2PbO). 


SPECIFIC GRAVITY 
2. True specific gravity shall be determined in accordance with the Stand- 
ard Method of Test for Specific Gravity of Pigments (Serial Designation: 
D 153) of the American Society of Testing Materials. 


MOISTURE 
3. Dry 2 g. of the sample for 2 hours at 105° C. The loss in weight is 
considered as moisture. . 


ORGANIC COLOR 
4. Boil 2 g. of the Sample with 25. cc. of 95-per-cent ethyl alcohol, jet 
Settle, decant off the Supernatant liquid; boil residue with water, decant as 
before and boil residue with very dilute NH,OH. If either the aleohol, water 
or NH,OH is colored, organic coloring matter is indicated. 


TOTAL LEAD AND INSOLUBLE MATTER 
5. Treat 1 g. of the sample with 15 ce. of HNO, (1:1) and sufficient H.O, 
to dissolve all PbO, on warming. If any insoluble matter is present, add 25 
ec. of water, boil, filter and wash with hot water. The insoluble matter con- 
tains free SiO, and should be examined for BaSO, and silicates, if appreci- 
able. To the original solution or filtrate from insoluble, add 20 ce. of con- 
centrated H,SO, and evaporate to SO, fumes; cool, add 150 cc. of water and 


720 Analysis of Lead Oxides 


150 ec. of 95-per-cent ethyl alcohol, let stand cold 2 nours, filter on a Gooch 
crucible, wash with 95-per-cent alcohol, dry at 105 to 110° C. and weigh as 
PbSO,. Calculate to PbO. Red lead is rarely adulterated, but should sample 
contain soluble barium compounds, the PbSO, obtained above will contain 
BaSO,. In this case, digest above precipitate with acid ammonium-acetate 
solution, filter off BaSO,, wash, ignite and weigh BaSO,. Calculate to BaO 


or BaCO,. In filtrate, determine the lead as PbSO, or PbCrO, If sample ;, 


contains significant amounts of calcium or magnesium, the HNO,-H.O, solu- 
tion is boiled till all lead is converted into nitrate and then the lead is 
determined as PbCrQ,. 

If calcium and magnesium are to be determined, proceed as follows: 
Precipitate the lead as sulfide from a slightly acid (HCl) solution, dissolve 
the PbS in hot dilute HNO, and determine the lead as sulfate. Boil the fil- 
trates from the PbS to expel H,S, add a little bromine water to oxidize iron 
(if present), boil to expel bromine, and then add NH,OH in slight excess. 
Filter off any precipitate of Fe(OH),+Al1(OH);; wash with hot water. (If 
appreciable, redissolve in hot dilute HCl and reprecipitate with NH,OH, 
ignite and weigh Fe,0,+Al,0;.) Manganese, if present, can be precipitated 
by adding bromine and NH,OH and warming; filter, wash with hot water, 
ignite and weigh as Mn,O, Unite all of the filtrates, make slightly acia 
with acetic acid, heat to boiling and pass H,S into the hot solution till satu- 
rated (20 to 30 minutes) ; add 5 g. of NH,Cl and let stand 5 hours; filter off 


any ZnS, wash with H,S water, dissolve the ZnS in hot dilute HCI and de- — 


termine the zine by titration with K,Fe(CN),. Or, boil off the H.S, filter out 
any separated sulfur and determine the zinc as Zn,P,0; Calcium may be 
determined in the filtrate from the ZnS by expelling H,S and then adding 


NH,OH and ammonium oxalate in the usual manner. Titrate with KMnQ,. — 


In the filtrate from calcium determine magnesium in the usual manner by 
precipitating with sodium-phosphate solution, finally weighing as Mg,P.0,. 


LEAD PEROXIDE (PbO,) AND TRUE RED LEAD (Pb304) 


(Method of Diehl* modified by TopftZnot applicable when substances are 3 
present, other than oxides of lead, that liberate iodine under conditions — 


given). 


6. Weigh 1 g. of finely ground sample into a 200-ee. Erlenmeyer flask, — 


add a few drops of distilled water and rub the mixture to a smooth paste — 


with a glass rod flattened on end. Mix in a small beaker 30 g. of c. p. | 


“Tested Purity” crystallized sodium acetate, 2.4 g. of c. p. KI, 10 cc. of © 


water and 10 cc. of 50-per-cent acetic acid; stir until all is liquid, warming 


gently; if mecessary add 2 to 3 cc. of water, cool to room temperature and — 


pour into the flask containing the red lead. Rub with the glass rod until 


nearly all the red lead has been dissolved; add 380 ce. of water containing 5 — 
or 6 g. of sodium acetate, and titrate at once with decinormal sodium thio- — 


sulfate, adding the latter rather slowly and keeping the liquid constantly in 


motion by whirling the flask. When the solution has become light yellow, — 
rub any undissolved particles up with the rod until free iodine no longer 
forms, wash off rod, add the sodium-thiosulfate solution until pale yellow, — 
add starch solution and titrate until colorless, add decinormal iodine solution” 


* Dingl. polyt. Jour., Vol. 246, p. 196. 
+ Zeitschrift fiir analytische Chemic, Vol. 26, p. 296. 


Analysis of Lead Oxides 721 


until blue color is just restored and subtract the amount used from the 
volume of sodium thiosulfate that had been added. 

Calculation.—The iodine value of the sodium-thiosulfate solution multi- 
plied by 0.942 — PbO,; the iodine value multiplied by 2.7 = Pb,O,; the PbO, 
value multiplied by 2.866 = Pb,O,. 

The sodium-thiosulfate solution and the starch solution shall be prepared 
as follows: 

Sodium-Thiosulfate Solution (decinormal).—Dissolve 24.83 oF. Oly G1 De 
sodium thiosulfate, freshly pulverized and dried between filter paper, and 
dilute with water to 1 liter at the temperature at which the titrations are to 
be made. The solution is best made with well-boiled water free from CO,, 
or let stand 8 to 14 days before standardizing. Standardize with pure, re- 
sublimed iodine, as described in Treadwell-Hall, “Analytical Chemistry,” 
Vol. II, p. 602 (1910), and also against pure potassium iodate; the two 
methods of standardization should agree within 0.1 per cent on iodine value. 

Starch Solution.—Stir up 2 to 8 g. of potato starch with 100 ce. of 1-per- 
cent Salicylic-acid solution, and boil the mixture till starch is practically dis- 
solved, thne dilute to 1 liter,* or as per Lord. ; 


DETERMINATION OF ZINC 
7. If in appreciable amount, evaporate off the alcohol from the filtrate 
from total lead, make alkaline with NH,OH, then acid with HCl, add 8 ee. 
more of concentrated HCl, dilute to about 250 cc. with water, heat nearly to 
boiling and titrate with standard K,Fe(CN), solution as described by Low. 
Report as ZnO (includes cadmium). Iron, copper or other interfering sub- 
Stances should first be removed as described by Low. 


WATER-SOLUBLE 

8. Digest 10 g. of sample with 200 cc. of hot water on steam bath for 1 
hour; filter on an 11-cm. S. & S. blue-ribbon paper and wash with hot water 
till no residue is left on evaporating a few drops of the washings. Evaporate 
filtrate to dryness on steam bath in a weighed dish, dry 30 minutes at 105° C., 
cool and weigh. Take up with water and if alkaline, titrate with tenth 
hormal acid and methyl orange; calculate to Na.CQ,. 

Another lot of water-soluble matter is tested for nitrates, nitrites, carbon- 
ates, sulfates, sodium and lead. 


TOTAL SILICA 
9. Digest 5 g. of the sample in a covered casserole with 5 cc. of HCl and 
15 ce. of HNO, (1:1). Evaporate to dryness to dehydrate. Cool, treat with 
hot water and HNO,, boil, filter, wash with hot acid ammonium-acetate solu- 
tion, then dilute HCl and finally hot water. Ignite and weigh as SiO,. The 
residue may be treated with H.SO, and HF in cases of doubt as to purity. 


*Lead Peroxide—If sample contains an appreciable amount of nitrate 
(nitrate has no effect on method), leach out water-soluble matter as below, 
dry residue and determine PbO, as above, calculating to basis of original 
sample. 

¥ “Notes on Metallurgical Analysis,” p. 103 (1903). 

t Low, “Technical Methods of Ore Analysis.” 


722 Analysis ot Lead Oxides 


CARBON DIOXIDE 


10. Determine carbon dioxide by the evolution method, using dilute HCl — 


and stannous chloride. 


DETERMINATION OF SOLUBLE SULFATE 
11. Sulfates other than Barium Sulfate.—Treat 0.5 g. of the sample with 
5 ee. of water, 3 g. of NH,Cl and 5 ce. of HCl saturated with bromine; digest 


(covered) on steam bath about 15 minutes, add 25 ce. of water, neutralize — 
with dry Na.CO,, and add about 2 g. more, boil 10 to 15 minutes; let settle, — 


dilute with hot water, filter and wash with hot water; redissolve in HCl, 


reprecipitate as above and wash thoroughly with hot water; acidify united — 
filtrates with HCl, adding a slight excess; boil and add slight excess of 10- 
per-cent BaCl, solution. Let stand on steam bath 1 hour, filter, wash with — 


hot water, ignite, and weigh BaSO,. Calculate to SO, (includes SO, formed 
from SO.,). ) 

Or, dissolve 0.5 g¢. of the sample in 25 ec. of water, 10 cc, of NH,OH (sp. 
gr. 0.90) and HCl in slight excess; dilute to about 150 ce. with water and 
add a piece of aluminum foil which should about cover the bottom of the 
beaker—this held on bottom by means of a stirring rod. Heat gently till 


all lead is precipitated, decant through a filter, pressing the lead sponge with ~ 


a flattened rod, and washing with hot water. Add to the filtrate a little 
pure bromine water, boil until bromine is expelled, add 15 cc. of 10-per-cent 


BaCl, solution, let stand on steam bath one hour, filter, wash with hot water, — 


ignite and weigh as BaSO, (any SrSO, present is not decomposed in this 
method. ) * 
IRON OXIDE 


12. Determine iron oxide by Schaeffer’s} modification of Thompson’s | 
colorimetric method; or, in a large beaker, treat 20 g. of the sample with 20 — 
cee. of water, 20 cc. of HNO, (sp. gr. 1.4) and 8 ec. of formaldehyde solution. — 


Warm till all PbO, is dissolved, dilute with water, warm, filter off insoluble 
and wash with hot water. Ignite filter and insoluble, evaporate with H,SO, 


and HF. To filtrate from insoluble add 14 ce. of H,SO, (1:1), filter off © 
PbSO,, and wash. Dissolve residue from HF and H,SO, in H,SO, and add to — 


filtrate from PbSO,; dilute to 500 ce. and determine iron colorimetrically in an 


aliquot, using same amounts of HNO,, H.SO, and formaldehyde in comparison ~ 


solution.t Calculate to Fe,Q,. 


Figg Method for Red Lead.f{—One gram of the red lead is 
treated in a glass mortar with 40 cc. of a saturated solution 
of sodium acetate in 5 per cent acetic acid, and a known excess — 


(40 of 50 ee. of 0.1 N solution) of sodium thiosulfate is— 


added. The reaction proceeds slowly and rubbing with pestle 
is needed to complete it. The presence of any undecomposed 


* The solubility of BaSO, is increased by the presence of aluminum chloride, 
See J. W. Mellor, “A Treatise on Quantitative Inorganic Analysis,” p. 615. 


+ Journal of Industrial and Engineering Chemistry, Vol. 4, p. 659 (1912). 


+ Lunge-Berl, “Chemisch-technische Untersuchungs-Methoden,” Bd, 2, S. 95, 


6th Ed. 
q E. F. Figg, J. Oil & Col. Chem. Assoc. 8, 101 (1925). 


ee ee ee ee ee ee 


Analysis of Lead Oxides 723 


red lead is easily observed in the clear solution, and rubbing 
is continued as long as any remains. The addition of a few 
ec. of 5 per cent potassium iodide solution facilitates the re- 
duction of the more resistant particles of red lead, and does 
not affect the titration. A few drops of starch solution are 
then added, and the excess of thiosulphate is titrated with 
0.1 N iodine solution. The large excess of sodium acetate 
prevents the precipitation of lead iodide, and the end-point of 
the titration is, in consequence, sharp. 


Schaeffer Method for Red Lead.—Treat 1 gram in a beaker 
with 15 ce. of nitric acid, sp. gr. 1.2 (110 ce. nitric acid sp. gr. 
1.42 to 100 ce. of water). Stir the sample until all trace of red 
color has disappeared. Add from a calibrated pipette or bur- 
ette exactly 10 ce. of dilute hydrogen dioxide (1 part of 3 per 
cent hydrogen dioxide to 3.5 parts of water). Add about 50 
ce. of hot water and stir until all the lead dioxide has passed 
into solution. In the case of some coarsely ground oxides the 
contents of the beaker may have to be gently heated to effect 
complete solution. After the oxide has completely passed into 
solution, dilute with hot water to about 250 ce. volume and ti- 
trate directly with a standard potassium permanganate solu- 
tion, having an iron value of 0.005. Titrate to the faint pink 
permanganate color. A blank titration on the hydrogen diox- 
ide solution must now be made. 


Into a beaker pour 15 ce. of nitric acid of above strength and 
add exactly the same amount of hydrogen dioxide (10 cc.). 
Dilute to 250 ce. with hot water and titrate with standard 
potassium permanganate solution to a faint pink color. 

The difference between the number of ce. of potassium per- 
manganate required for the blank titration and the number 
required for the red lead titration is the amount required for 
the hydrogen dioxide which was reacted on by the red lead. 
The difference between the two amounts of potassium per- 
manganate required multiplied by 3.058 grams gives the per- 
centage of red lead present. The difference multiplied by 
1,067 gives the percentage of PbOz present. 


In certain instances it is found that red lead in flake form 
is soluble only with the greatest difficulty by the above pro- 
cedure. In cases where this difficulty is encountered the fol- 
lowing method will be found to give excellent results, espe- 
clally for flake red lead. 


724 ? Analysis of Lead Oxides 


Digest 1 gram of the sample in a beaker with 15 ce. of nitric 
acid made up of a strength as given in the previous method. 
Boil the solution for a short time, add 10 ee. of a standard 
oxalic acid solution, the strength of which has been previously 
determined. Add 2 cc. of sulphuric acid (1:1). Boil the solu- — 
tion and titrate with a standard solution of potassium per- ~ 
manganate having an iron value of 0.005. <A blank titration — 
on the same amount of oxalic acid must be made. The differ- 
ence between the amount of potassium permanganate required 
for the blank titration and that required for the red lead titra- 
tion multiplied by the factor 3.058 or 1.067 will give the con- 
tent of red lead or lead dioxide according to the proportions 
in the previous analysis. 


Copper Content of Red Lead.—Treat 30 grams of the sam- 
ple with 40 cc. (1:1) nitric acid, using great care that the 
violence of the reaction does not cause the sample to froth — 
over the beaker. Slowly add 30 to 40 ce. of 3 per cent hydro- 
gen peroxide,* stirring constantly. Boil until solution is — 
effected. Add 32 ce. (1:1) sulphuric acid, stirring constantly — 
while adding. Let the precipitate settle, and decant filtrate 
through a coarse filter paper. Wash four times by decanta- — 
tion, using small portions of warm, distilled water. Transfer — 
the precipitate to the paper, wash again and allow to drain. 
Make the filtrate neutral with ammonium hydroxide and add — 
4 cc. excess. Boil for a short time and filter. Wash the pre- — 
cipitate well with warm water, and reserve for the determina- 
tion of the iron. Render the filtrate acid with special ec. p.— 
hydrochloric acid, adding not more than two drops excess. 
Add six drops of (1:10) potassium ferrocyanide solution, filter — 
through close filter papers using two to each funnel. Catch — 
the filtrate and inspect for copper ferrocyanide. Let the pre- 
cipitate drain well without washing. Dissolve the copper fer-— 
rocyanide off of the paper with alternate washings of small — 
portions of ammonium hydroxide and hot water. Wash well © 
and keep the bulk to 30 or 40 ce. Render slightly acid with — 
hydrochloric acid, adding not over two drops excess. Transfer — 
to a 100-cc. Nessler tube, and dilute to mark with distilled ~ 
water. The copper is then determined colorimetrically ac- ¢ 


*Sodium sulfite c.p. may be used in place of hydrogen peroxide for ofrectiii 
the solution of lead peroxide, adding it dry in small portions and-boiling until — 
no brown lead peroxide is present. 


: 
: 


Analysis of Lead Oxides 725 


cording to a modification of the method of Carnelly. In an- 
other Nessler tube, place 10 cc. of 5 per cent ammonium ni- 
trate solution, two drops concentrated nitric acid and 90 ce. 
distilled water, add from a burette graduated to tenths of 1 ce. 
standard copper sulphate solution until the color matches the 
sample under examination. 


Standard Copper Sulphate Solution.—< Dissolve 0.393 gram 
of pure CuSO..5H20, in one liter of distilled water. 1 cc. = 
0.0001 gram of copper,’’ or 0.00033 per cent when using a 30- 
gram sample. 


Copper may also be determined gravimetrically as follows: 
Twenty grams of the pigment contained in a 200-ce. flask are 
dissolved in nitric acid (50 ce, concentrated nitric acid to 100 
cc. water). Boil to complete solution. Add 40 ec. of dilute 
sulphuric acid (1:1), boil gently for one hour and allow 
to cool. Filter off the lead sulphate and wash the precipitate 
thoroughly. Nearly neutralize all the free acid present with 
ammonium hydroxide, render slightly acid with hydrochloric 
acid, warm the solution and pass in hydrogen sulphide until no — 
further precipitation of sulphide occurs. Filter off the pre- 
cipitate without washing, using some of the filtrate to transfer 
the last traces of sulphide to the filter paper. Dissolve the 
precipitate in a little nitric acid and wash the filter paper 
thoroughly with hot water. Add 3 ce. of concentrated sul- 
phuric acid, evaporate until the white fumes of sulphurie acid 
are evolved and allow the solution to cool. Add a little water 
and allow to stand for some hours. Filter off the lead sul- 
phate, washing with hot water containing a little sulphuric 
acid. 


Heat the filtrate to boiling and precipitate the copper as sul- 
phide with hydrogen sulphide in an ammoniacal solution. Fil- 
ter off the copper sulphide through an ashless filter paper, 
wash, ignite and weigh in a covered porcelain crucible, from 
which the heat and cover are occasionally removed for a few 
seconds. 


The precipitate will consist of a mixture of CuO and Cu.S. 
Since the percentage of copper is the same in both of these, the 
copper may be determined by multiplying the amount found by 
the factor 0.799. 


726 Analysis of Lead Oxides 


Iron Content of Red Lead.—For the iron determination, use 
the precipitate of iron hydroxide removed from the copper — 
solution, proceeding as follows: Dissolve the precipitate con- — 
tained on the paper with (1:1) hydrochloric acid, collecting the ~ 
filtrate in a 300-ce. volumetric flask. Wash the paper free from E 
acid with hot, distilled water, dilute to mark, and mix thor-— 
oughly. Place 10 ce. in a 100-cc. Nessler tube, add three drops ; 
nitric acid, 10 ec. (1:15) ammonium sulphocyanide solution, — 
dilute to mark and compare with a standard iron solution, = 


ai 


Plath SRI 2 


The color is compared with a blank made in the following 
manner: <A solution of ferric ammonium sulphate of known — 
strength is required. This is made by dissolving 0.7022 gram — 
of ferrous ammonium sulphate in water. Acidify with sul- ~ 
phuric acid, heat to boiling and add a solution of potassium — 
permanganate until all the iron is converted to the ferric con- ‘ 
dition. Only the very slightest pink tinge may be present — 
after the addition of the potassium permanganate, as this ; | 
tinge will fade away, while the presence of a pink color tends ~ 
to vitiate the results. Allow the solution to cool and dilute to 
one liter. One ee. of this solution equals 0.0001 gram of iron. 


Prepare the blank by pouring into a 100-ee. Nessler cylinder, 
10 ce. ammonium sulphocyanide solution, and three drops of — 
concentrated nitric acid. Dilute to 100 ec. and titrate to the © 
exact color developed in the sample under examination, by the — 
addition of the standard ferric ammonium sulphate solution. — 
One cc. of this solution equals 0.01 per cent iron as the 10 ce. © 
removed from the flask contained 1 gram sample. It will be — 
found that the color can be accurately compared to within 
0.001 per cent of iron content. 


Te ca SET LE ae 


pict 


Free Silica Content of Red Lead.—The free silica may be de- — 
termined by dissolving the litharge in dilute nitric acid. Heat 
to boiling, filter, wash, ignite and weigh as silica. 4 


omer: 


Free Metallic Lead—Two grams of the sample are treated _ 
in a beaker with hot water and just sufficient acetic acid ig 
slowly added, to dissolve the lead oxide. Stir the solution well © 3 
and note whether any lead silicate remains undissolved. 4 
Should such remain, continue stirring until solution has been 4 


= 


. 
os 
Re 


Analysis of Lead Oxides 727 


effected. The solution should never have greater than a 5-per- 
eent acetic acid strength. 


Filter the solution and wash the residual metal three or four 
times by decantation with hot water, having all the wash 
water pass through the filter paper, which is finally thoroughly 
washed with hot water. Transfer any metal on the filter 
paper to the beaker containing the residual lead nitric acid 
and heat to solution. Dissolve in nitric acid and determine 
in the usual manner. 


CHAPTER XLI 


ANALYSIS OF REDS OTHER THAN IRON OXIDES. 


Cadmium Red. The cadmium red pigments* are a recent — 
development and consist of cadmium sulfide (CdS) contain- 
ing various amounts of cadmium selenide (CdSe). Barium ~ 
Aeitiie may also be present in the form of cadmopone. The — 
colors range from orange to maroon, depending upon the ~ 
proportions of the ingredients. As the fumes from selenium ~ 
are poisonous, the analysis should be done in a hood. 


Insoluble Matter.—One gram of the pigment is heated ina ~ 
beaker with concentrated nitric acid and Br. until the selenium — 
color is discharged. ‘The solution is then diluted with water ~ 
and after digesting 1 hour, the BaSOs. is filtered off and 
weighed. The sulfur which was present as sulfide may be ~ 
determined in the filtrate from the insoluble BaSO: by boiling — 
with concentrated HCl to reduce the selenic acid to selenious — 
acid, diluting to 200 ec., heating to boiling and precipitating 
as BaSO: with 10% BaCl, solution. 


Selenium.t—One gram of the pigment is heated with con- — 
centrated nitric acid until free from color and the insoluble ~ 
matter is filtered off. 10 grams of c. p. NaCl is added and 
the solution concentrated to about 25 ec. HCl is then added 
to replace the HNOs. The solution is then made up to 100 ee. 
so that it contains at least 50% of concentrated HCl (1.19) 
and heated to 100° C. SOs is then passed through the solu- 
tion, or NaHSOs is added until the Se is entirely precipitated. 
The digestion is continued until the selenium is converted to 
the black modification, filtered on a Gooch crucible, washed 
first with 50% HCl, then with dilute HCl and then with water. 
It is dried at 105° C. and weighed as metallic selenium. 


Cadmium.i—The filtrate from the determination is concen- 
trated to about 25 ec., nearly neutralized with NHs, diluted — 
to 100 ce. and then saturated with H:S. The precipitate is 
filtered, washed and then dissolved in dilute HCl. The solu- 
tion is evaporated to dryness in a weighed Pyrex beaker, 5 


at ae — t . Fi egy - Ss a 
ae Maa eg Mee rate. aan NEA ll gh ini e Teodh eS 


*H. Dudley Ward, J. Oil & Colour Chem. Soc. X 4, (1927.) 
*Scott. Standard Methods of Chemical Analysis. 
tSeott. Standard Methods of Chemical Analysis. 


ON So ee oe Seen maT ee : as 
eel Nee ie te a a arr 


Analysis of Reds Other Than Iron 729 


ec. of concentrated H:SO. added and the excess expelled at 
low red heat. 


CdSO: X 0.539 = Cd 


Cadmium Lithopone (yellow or orange). This pigment 
is a chemically precipitated pigment containing approximately 
68 per cent barium sulphate, the balance consisting princi- 
pally of yellow cadmium sulphide with some zinc sulphide. 
It is not affected by hydrogen sulphide. For moisture, water 
soluble, total sulphides, and oxides, see methods for lithopone. 


Method for Cadmium and Zine Sulphides.—Take 1 gram of 
the sample in a 200 ee, beaker, add 15 ce. of concentrated inl OlR 
mix, and add in small portions about 1 g. KC1Os, then heat on 
the steam bath until about half of the liquid is evaporated and 
the yellow color of the CdS has disappeared. (If necessary 
a few ce. of concentrated HNO; may be added at this point to 
effect the solution of the CdS.) Then add 15 ce. of 1-1 sul- 
phuric acid and evaporate to fumes of SOs. Cool, dilute with 
100 ce. of water, filter off, and weigh the insoluble barium sul- 
phate and examine it for alumina and silica (not likely to be | 
present). 


To the filtrate from the insoluble, add water until volume is 
200 ce. Cool and pass a rapid stream of H2S gas through the 
solution for 15 minutes. Add dilute NH.OH, drop by drop 
until yellow cadmium sulphide begins to precipitate. Heat 
the solution to about 90° C. and again pass HS for five min- 
utes. Boil the solution for a few minutes, let settle,, and filter 
through close-grained paper, washing the precipitated CdS 
with cold 10% sulphuric acid and with hot water. Save fil- 
trate for zine. 


Dissolve the sulphide on the filter in 1-2 HC] in a clean 
beaker, add 15 ce. (1-1) sulphuric acid, take to fumes, and 
repeat precipitation of CdS. Filter through weighed Gooch 
crucible, wash with 10% sulphuric acid and hot water, dry at 
110° ©. for one hour, and weigh as CdS. 


Combine the two filtrates from the CdS precipitation, cool 
thoroughly, make slightly alkaline with NH,OH, and pass a 
rapid stream of H2S gas for ten minutes. Heat to boiling, let 
settle, filter on fine-grained paper, wash well, and ignite care- 
fully in crucible to ZnO. Factor ZnO to ZnS — 1.1975. 


730 Analysis of Reds Other Than Iron 


Cuprous Oxide Red in Antifouling Paints. The red cuprous ~ 
oxide used in antifouling paints can be analyzed in accordance ~ 
with the following method: Weigh accurately about 0.25 g. of 
the dry sample into a 250-ce. ground glass stoppered Hrlen- 
meyer flask. Add 10-15 ec. of acid ferric chloride solution — 
(200 g. FeCls. 6 H2O in 500 ce. of 1:1 HCl), and a few glass © 
beads, stopper, and rotate until the oxide is completely dis- 
solved (usually within 2 or 3 minutes on high-grade finely 
ground samples). Warm on the steam bath, if necessary, — 
but it is not advisable and generally unnecessary. Add 9 cc. © 
of syrupy phosphoric acid, 200 ce. of cool distilled water, and — 
titrate the ferrous iron with decinormal KMnO, to the first — 
permanent (30 seconds) color change. A blank (usually about : 
3 drops) should be run on the reagents. 


1 ee. O. 1 N KMnO, = 0.00636 g. Cu. 
= 0.00716 Cuz0 


Analysis of Vermilions. The following portion of Walker’s® — 
method will suffice for the examination of Mercury Vermilion. ~ 
Should the analyst desire to determine the sulphide of mereury — 
present or make a more complete examination reference — 
may be made to the original method. . 


“True vermilion, or, as it is generally called, English ver- — 
milion, is sulphide of mercury. On account of its cost it is — 
rarely used in paints, and is liable to gross adulteration. It — 
should show no bleeding on boiling with alcohol and water and ~ 
no free sulphur by extraction with carbon disulphide. A — 
small quantity mixed with five or six times its weight of dry 
sodium carbonate and heated in a tube should show globules — 
of mercury on the cooler portion of the tube. The best test — 
for purity is the ash, which should be not more than 0.5%. 
Make the determination in a porcelain dish or crucible, using ~ 
2 grams of the sample. Ash in a muffle or in a hood with a— 
very good draft, as the mercury fumes are very poisonous. — 
It is seldom necessary to make a determination of the mer-— 
cury. Genuine mercury vermilion is at the present time little | 
used in paints.’’ | 


*P, H. Walker, Miscellaneous Publications, No. 15, U. S. Bureau of — 
Standards, p. 32. 7 


731 


f Reds Other Than Iron 


1S O 


Analys 


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aBUBIO a4eyIdDeIg “aBURIO -Idioeid poy SeossdAIOYA -NjOSs osuvIQ -[OS AjIpeey we 0} SeAlOssIqT ‘eTqnjos ANYsIIS Gay VuVvd 
HO®N+ uOoI}N{Ip uo p2e7814U90U00 uoT}NI{Ip uo pe}e813Us0uU00 uolgn{Ip uo peye13U90U09 
WYOKOUOTHO TIOHOOTV IOH ¥OS°H HO®N 


SaMVT GANOTOOD ANOS AO NOILVOIALLNAGI AHL YOd SLSAL AALLV.LITVAO 


Ps Analysis of Reds Other Than Iron 


Identification of Color Lakes.—There is given on page 731 a . 


chart showing the results obtained in this laboratory upon a — 


number of organic colors used in the paint industry. The tests 


were made with five different reagents. The method of test — 


consisted in pouring the reagent on a watch glass and then ~ 


incorporating a small amount (approximately 0.1 gram) of 
the color lake in the reagent by means of a stirring rod. The 


precipitates noted in many instances might be composed of © 


an inert base on which the dyestuff was formed. 


Orgamc Reds.—Organic lakes are used for most of the bril- © 


liant red, scarlet and vermilion shades. These organic color- 


ing matters are sometimes precipitated on red lead, orange ~ 


mineral or zinc oxide; but as a usual thing the base is barytes, 


whiting or china clay. Paranitraniline red, a compound of ~ 


diazotized paranitraniline and beta-napthol, is largely em- 
ployed; but a number of colors may be used. ‘The examina- 
tion of these reds follows the method as communicated to 
the writer by EK. F. Hickson. 


Qualitative Tests for Reds.—In qualitatively testing ver- 


milions (para red, toluidine red, and lithol red) the following — 
suggestions may be useful: (1) Para Red. The intense pur- — 
ple color in a mixture of alcohol (ethyl or denatured) and — 


sodium hydroxide solution distinguishes para red from the ~ 
other two. (2) Toluidine and Inthol Reds. (a) Chloroform — 


Test.—A small amount (0.1 g. or less) of C. P. toluidine red, — 


when stirred into 100 ce. of warm chloroform, gives a practi- — 
eally clear, orange red solution within one hour. Lithol red — 


eo 


under the same conditions remains practically undissolved, 
even overnight, giving a nearly colorless filtrate. (b) Sodwm 
Carbonate.—C. P. toluidine red is exceptionally resistant to 
strong alkalies and acids. A boiling solution of fairly strong 
sodium carbonate will have practically no effect on the bright 
orange red color of the toluidine, whereas the lithol red (bar- 
ium lake), will be converted to the sodium salt. Make both 
liquids slightly acid with dilute sulphuric acid and without 
filtering, place a piece of clean, freshly washed wool in each, 
and allow to remain for 10 minutes. Take each piece of wool 
and wash thoroughly with mild soap and water, taking care 
to wash off any absorbed pigment particles. The lithol dyes 
the wool a fast, uniform pink (coral) color that will not wash 
out. the toluidine does not dye the wool. 


Analysis of Reds Other Than Iron 733 


Percentage of Pigment in Paste or Paint.—In separating 
the pigment from the vehicle, petroleum ether has been found 
to dissolve out only a slight amount of organic color. An- 
other suggested solvent for separating the pigment from ve- 
hicles is a mixture of two-thirds to three-quarters petroleum 
ether and one-third to one-quarter ethyl ether. Benzol or 
the mixed solvents do not work well with some samples of 
vermilion paint. (The reader is also referred to Federal 
Specification Board Specification No. 66 for Red Enamel, in 
the back of this book.) Weigh accurately about 15 g. of the 
paste or paint into a weighed centrifuge tube. Add 20 to 30 
ce. of petroleum ether, mix thoroughly with a glass rod, wash 
the rod with more of the petroleum ether, and add sufficient 
of the reagent to make a total of 60 ce. in the tube. Place the 
tube in the container of a centrifuge, surround with water, 
and counterbalance the container of the opposite arm with a 
similar tube or a tube with water. Whirl at a moderate speed 
until well settled. Decant the clear supernatant liquid. Re- 
peat the extraction twice using petroleum ether. After draw- 
ing off the last extract, set the tube on top of a warm oven for 
10 minutes, then in an oven at 110 to 115° C. for two hours. 
Cool, weigh, and calculate the percentage of pigment. Grind 
the pigment to a fine powder, pass through a No. 80 screen to 
remove any skins, and keep in a stoppered bottle. 


Analysis of Pigment.—Test the pigment first qualitatively. 
Place a small portion of the pigment in a 50 ec. beaker and 
add about 25 cc. of alcoholic KOH or NaOH. Para-red will 
turn a dark reddish purple. Pour off the colored solution, 
and repeat until all the color is in solution and a white base 
remains. Add a little HNOs to some of the base to show the 
presence of carbonate. A white base, giving no effervescence 
or test for COs, is probably composed of silicates or silicate 
and barium sulphate. Occasionally the base contains orange 
mineral; the addition of HNOs will turn this pigment brown 
and bleach out on adding a few drops of dilute NaNOz solu- 
tion. 


Percentage of Color—Weigh accurately about 0.5 g. por- 
tion of the pigment into a 250 ce. beaker, add about 100 ce. of 
warm chloroform, and stir with a glass rod, breaking up any 
lumps. Decant the colored solution through a weighed Gooch 
crucible, and leave the residue in the beaker. Add a 50 ce. 


734 Analysis of Reds Other Than Iron 


SS SSS SSS SSS SSNS 


portion of chloroform to the residue and stir well with a glass © 


rod, breaking up any lumps. Decant the colored solution 
through the Gooch crucible and repeat the washing of the 
residue in the beaker with 50 ce. more of chloroform. Finally 
transfer the residue onto the Gooch crucible, and continue the 
washing with chloroform from a wash bottle until the base is 
white or the washings colorless. Dry the Gooch crucible at 
105-110° C. to constant weight and report the loss as ‘‘pure 
color.’’ 


Nore.—In case the examination of the pigment shows calcium carbonate 
to be absent and the base to be barium sulphate and silicates, a direct loss on 
ignition using 1 g. of the sample will generally check the above within 0.5 per 
cent. 


In case the base contains calcium carbonate, hydrated clays, 


? 
alumina, etc., an ignition loss cannot be calculated to organie 


color, since ids results are too high, due to loss of combined 
water in the clay. 


The above method for percentage of color will give in most 
cases a base free from organic color with about 250-300 ee. of 
chloroform. 


Some samples have been washed with the following mixture ~ 
for the percentage of color and satisfactory results were ob- — 


tained: 


10 vol. ethyl ether, 6 vol. benzol, 4 vol. methyl alcohol, 1 vol. 
acetone, and made lesen with NaOH. 


This is followed with alcoholic NaOH, alcohol and aha 


A.S.T.M. TENTATIVE SPECIFICATIONS FOR 
COMMERCIAL PARA RED 


1. These specifications cover a red paint pigment commonly known as com- 


mercial para red. The pigment may be purchased in the dry form or ground ~ 


in oil or in japan to form a paste. 


MANUFACTURE. 
2. (a) Dry Pigment.—The pigment shall be para nitraniline red toner, pre- 
cipitated on a white base consisting of barium sulfate with or without siliceous 
materials. 


(b) Paste in Oil.—The paste in oil shall be made by thoroughly grinding 


the specified pigment in pure raw or refined linseed oil. 


(c) Paste in Japan—tThe paste in japan shall be made by thoroughly - 


grinding the specified pigment in high-grade grinding japan. 


os alent 


ara GF i am 


SPEC af ctl ent NER tain eet Be 


er es gee aE ah li 
fia o eatin oe Mei Nas era 


aes 


CNS mer 
jie ae Tit 


a 


=. 


Opin geen praia: 


Analysis of Reds Other Than Iron 735 
es Lc ite aac ea 


PROPERTIES AND TESTS 
3. (@) The mass color and character of the tint formed by mixture with 
a white pigment shall be the same as, and the strength shall be not less than 
that of a sample mutually agreed upon by the buyer and seller. 
(6) Dry Pigment.—The dry pigment shall conform to the following require- 
ments: 
MAXIMUM MINIMUM 


Pure organic coloring matter (para red), per cent .. 10.0 
Bereemur SIL Pale, Per Cent .< 6s. os cc cece cece oes -. 60.0 
amemerMPTMAUOTIAL Cr. sens cccs «cs ce ea cc cee « remainder remainder 
Coarse particles retained on a No. 325, screen, 

OUST on GIB Ano BS ie ea 1.5. 


(¢) Paste in Oil—The paste as received shall not be caked in the con- 
tainer and shall break up readily in oil to form a smooth paint of brushing 
consistency. It shall mix readily in all proportions, without curdling, with 
linseed oil, turpentine or volatile mineral spirits, or any mixture of these 
substances. The paste shall conform to the following requirements: 


MAXIMUM MINIMUM 


ele EM TG OE MESO cc, ss ices occ vs cose cca ce cae be eee 78.0 
RENN OUNCE. ie cic kd ic v0'c o'ece tcc s Gee 22.0 Se 
~ Moisture and other volatile matter, per cent.... 0.7 
Coarse particles and skins (total residue re- 
tained on a No. 325 screen, based on pig- 
PISPEN I EIT ORT ieee wae vices 0 wale vw asd wecaee 


(d) Paste in Japan.—The paste as received shall not be caked in the 
container and shall break up readily in turpentine to form a smooth paint of 
brushing consistency that will dry within one hour to a hard flat coat that can 
be varnished within five hours of the time of application, without streaking 
or bleeding. The paste shall conform to the following requirements: 


MAXIMUM MINIMUM 

Ser RB POCOTYE 62S oe. oc oie s,s c's vos vee nes een aah 78.0 
Pomc losjapaiy, per Cents. ke... cece ees cos toe 22.0 sr 
Coarse particles and skins (total residue re- 

tained on a No. 325 screen, based on pig- 

BCPC re aiid 6c cic vie dey'e 04 bs 00 Bw bles 2.0 
Non-volatile matter in the vehicle, per cent of 

SEG Peps in cig a a oie 005i do ae Rae we obo hBe ees 40.0 


4. One sample shall be taken at random from each lot of 1000 packages or 
fraction thereof. If the packages are of such size that 1000 amount to more 
than a carload, one sample shall be taken at random from each carload. 


CHAPTER XLII 


ANALYSIS OF YELLOW, ORANGE, BLUE AND GREEN PIGMENTS ~ 


The material on this subject presented in the previous edi- 
tions of this work has been utilized in the drafting of A. 8. 
T. M. specifications which are given below. These methods 

are followed by special methods of general interest. | 


A.S.T.M. STANDARD METHODS OF ROUTINE ANALYSIS OF YELLOW ~ 


AND ORANGE PIGMENTS CONTAINING CHROMIUM COMPOUNDS, 
BLUE PIGMENTS AND CHROME GREEN. 
GENERAL METHODS. 


SPECIFIC GRAVITY. 


1. True specific gravity shall be determined in accordance with the 
Standard Method of Test for Specific Gravity of Pigments (Serial Designa- 
tion: D 158) of the American Society for Testing Materials. 


TINTING STRENGHT* 
2. The colors should always be compared with a carefully selected stand- 
ard. Weigh out accurately a portion of the color (0.02 g. of yellow; 0.01 g. 
of green or blue), place on a large glass plate, add 24 drops of bleached lin- 


seed oilf (86 drops with blues). and mix with a clean steel spatula until the 
mass appears to be homogeneous; add pure ZnO (2 g. for yellows or greens, 


3 g. for blues), and grind with a circular motion 50 times, using a flat-bottomed 
glass pestle or muller; gather up with a sharp-edged spatula and grind out 
twice more in like manner, giving the pestle a uniform pressure. Next weigh 
out a similar amount of the standard, and treat in exactly the same manner 
as described above. Transfer portions of each paste to a microscope slide, 
quite close together, and then draw a palette knife across both samples so as 
to make them meet in a line (differences in tint are then easily seen). Com- 
pare the tints as shown on both sides of the glass. The amount of pigment 
used will vary with the tinting strength, but the amounts indicated will gen- 
erally suffice. 


If it is desired to express quantitatively the tinting strength of the pig- r 
ment, consider the standard pigment as having a tinting strength of 100, and 
then vary the amount of the standard pigment until the tints are matched. 


For example, let the amount of standard pigment for 100 strength test be § 
0.05 g. (=A). Vary this amount in units of 5 per cent, thus 0.0475 or 0.0525. — 
Let the amount required to match a given strength equal B, then 

B 
cae eee 
A 


equals the tinting strength of the sample to be tested. 
If the tone varies it may be difficult to make this measurement. 


*Hollep, “Analysis of Paint and Varnish Products,” 1912, p. 126. : 
+The use of “oxidized” oil should be avoided (oil that ha sbecome “fatty” 
by standing in a can or bottle). Poppy oil could be used but it is quite as — 
necessary to have it reasonably fresh as when linseed oil is used. In either — 
case “stringy” pastes are not reliable. . 


Yellow, Orange, Blue, and Green Pigments 737 


ADDED COLORING MATTER. 
3. Test the pigment successively with hot water, 95-per-cent ethyl alcohol, 
and chloroform. The solutions should remain colorless. Other reagents may 
be tried.* 


METHODS OF ANALYSIS OF YELLOW AND ORANGE PIGMENTS. 
CHROME YELLOWS, AMERICAN VERMILION, BASIC LEAD CHROMATE. 
A pure chrome yellow should contain only lead chromate and other 
insoluble lead compounds. 


MOISTURE. 
4. Heat 2 g. at 105°C. for two hours. The loss in weight is reported as 
moisture. 


INSOLUBLE MATTER. 

5. Treat 1 g. with 25 cc. of concentrated HCl and boil for from 5 to 10 
minutes in a covered beaker, adding about 6 drops of alcohol to the boiling 
liquid, one at a time. Dilute to 100 ce. with hot water and boil for from 5 to 
10 minutes (the solution should be complete). Filter the hot solution (if 
insoluble matter is present) and wash with boiling water till washings are 
free from lead and chlorine. Ignite the insoluble matter, weigh, and examine 
for SiO,, BaSO,, and A1,O,. 


TOTAL LEAD. 

6. Add NH,OH to the filtrate from the insoluble matter (or the original 
solution), until a faint precipitate begins to form, then add 5 cc. of concen- | 
trated HCl (sp. gr. 1.19), dilute to 500 cc., and pass into the clear solution a 
rapid current of H,S until all of the lead is precipitated as PbS. Let the 
precipitate settle, filter, wash with water containing some H,S. Boil the filter 
and precipitate with dilute HNO, until all of the lead has dissolved, filter 
and wash thoroughly with hot water. To the filtrate, add 10 cc. of H.SO, 
(1 : 1), evaporate until copious fumes of SO, are evolved, cool, add about 75 ec. 
of H,O and then 75 cc. of 95-per-cent ethyl alcohol. Let stand about one hour, 
filter on a Gooch crucible, wash with dilute alcohol, dry, ignite, and weigh as 
PbSO,. Save the alcoholic filtrate from the PbSO,, evaporate nearly to dryness 
and add to the filtrate from the PbS. 


CHROMIUM (Iron, ALUMINUM). 

7. Heat the filtrate from the PbS to expel H.S and, if iron is present, add 
a few drops of HNO, and boil about two minutes. Render the solution just 
alkaline with NH,OH, boil a few minutes, filter, and wash with hot 2-per-cent 
NH,Cl solution. (If the sample contains an appreciable amount of zinc, a 
. double precipitation should be made.) In the absence of iron and aluminum 
this precipitate may be ignited and weighed as CroO3. If iron and aluminum 
are present, dissolve the. NH,OH precipitate with hot dilute HCl, washing 
the paper with hot water; evaporate to about 100 ce., cool, add NH,OH until 
alkaline, and then add Na,O, (containing at least 90 per cent of Na,O,) 


*For details consult Zerr, “Tests for Coal-Tar Colors in Aniline Lakes” 
(English translation by C. Mayer) ; Schultz and Julius, “A Systematic Survey 
of the Organic Coloring Matters,” Hall, “The Chemistry of Paints and Paint 
Vehicles,” and Mulliken, “Identification of Pure Organic Compounds,” Com- 
mercial Dyestuffs, Vol. III. ; 3 


738 UME Orange, Blue, and Green Pigments 


in small portions to the cooled solution (10 to 12° C.) until oxidation is com- 
plete, keeping the beaker covered. Digest until all of the chromium and 
aluminum has been dissolved, adding more Na,O, if necessary. Filter off the 
Fe(OH); wash thoroughly with hot water. ignite and weigh as Fe,Os; or, 
dissolve the precipitate in HCl and determine the Fe content volumetrically. 
Make up the filtrate from the Fe(OH), to 250 ec. in a graduated flask, and — 
mix. Render an aliquot portion acid with H.SO,, boil to expel any free oxygen, ¥ 
cool. add an excess of standard (NH, ),Fe(SO,),.6H,O solution and titrate — 
back with 0.1 NV K,Cr,0, solution, using K;Fe(CN)¢ as outside indicator, ; 
(The CrO, may also be determined by acidifying the aliquot portion with : 
acetic acid, precipitating as PbCrO, or BaCrO,, and finally weighing on a — 
Gooch crucible.) To determine Al,O:, make an aliquot portion of the filtrate — 
from the Fe(OH), acid with HCl, and then just distinctly alkaline with — 
NH,OH, heat to boiling, let settle, filter, wash with hot 2-per-cent NH,Cl solu- % 
tion, ignite and weigh as Al,O,. If iron and aluminum are not to be determined = 
or are present in negligible amounts, the first NH,OH precipitate may be dis- — 
solved in dilute HCl, oxidized with Na,O,, acidified with H 28O,, boiled, and — 
CrO, determined volumetrically. The CrO, in the absence of other oxidizing F: 
substances, may be determined on 1 g. of the pigment by Schwartz’s method — 
(Fresenius Quantitative Chemical Arpaia Ed. 6, Vol. 1, p. 424), or by the 4 
persulfate method,* as follows: 
SFor x. ys chrome yellows use an 0.25-g. sample, for ¢. p. chrome greens e 
use an 0.5 sample, and for commercial chrome greens use a 1-g. sample. — 
Weigh aM ee nats transfer to a 600-cc. Pyrex beaker, add 25 ec. of concen- — 
trated H,SO,, and fume lightly on a hot plate for 3 or 4 minutes. Excessive : 
fuming or cooking over a hot flame is neither necessary nor desirable, as it # 
may produce the difficulty soluble anhydrous chromium sulfate. The Prussian 
blue color is destroyed in a few minutes. Cool, cautiously dilute with water z 
to 300 ce. stir, and heat to boiling. To the boiling solution add a small 4 
amount of permanganate (0.5 to 1 ce. of 0.1 N KMnO,) to insure the presence ¥ 
of some manganese. Then add to the boiling solution 10 ce. of AgNO, solution 
(2.5 g. in enough water to make 1 liter) and 20 ec. (adding this slowly) of © 
ammonium persulfate solution (4 g. of ammonium persulfate of full strength ee 
dissolved in 20 ce. of water). The hot solution should show the usual perman- ~ 
ganate color. If this color does not develop, or if it disappears, add more — 
persulfate. When the permanganate color is permanent, continue the boiling 
(best done on a hot plate) for 10 to 15 minutes to destroy excess persulfate. | 
Then add 5 cc. of dilute HCl (1:3) and boil for 5 to 8 minutes to reduce the — 
oxidized manganese. The color now should be the usual chromate yellow. — 
Cool to above 20° C. and titrate either electrometrically with ferrous sulfate,7 4 
or add a measured excess of ferous sulfate solution (beyond the deep grass: — 
green color) and titrate back with 0.1 N permanganate. The first faint per- 4 
manent darkening of the green color is taken as the end point. | 
Correction for a blank (about 0.2 cc. of KMn0,) due to color, ete., should ~ 


be made. 


Exte 


rr tee 
40 a Ser. 


*E. F. Hickson. Circular No. 294. Scientific Section, Am. Paint and Varnish “a 
Manufacturers’ Assn., November, 1926. a 
+Kelley, Journal of Industrial and Engineering Chemistry Vol. 15, p. 1058 x 

(1921). 
“ fis 


ie 


a: a 


Yellow, Orange, Blue, and Green Pigments 739 


NOTES. 


In commercial chrome greens containing silicates and barium sulfate, filtra- 
tion to remove the “acid insoluble matter” after fuming the sample with acid 
and diluting is advisable though not necessary. The end point of the sub- 
sequent titration of the clear solution is easier to see, and there is less chance 
for “bumping” during boiling if these are removed. 

In the case of ¢c. p. greens and yellows, the solution, after fuming with 
sulfuric acid and diluting, could be filtered and the precipitated lead sulfate 
weighed directly for total lead. This would likewise give a clear filtrate for the 
chromium titration. 

The important precautions are to avoid overheating with sulfuric acid, and 
to make sure that the persulfate (solid material) has not deteriorated. It 
should contain over 90 per cent of the reagent. 


ZING, CALCIUM, AND MAGNESIUM. 


8. Precipitate any zine in the filtrate from the first NH,OH precipitate 
with H,S§, filter, wash with dilute (NH,).S8, dissolve the zine sulfide in dilute 
HCl, and determine the Zn content volumetrically by K,Fe(CN), method. In 
the filtrate from the zinc sulfide, determine calcium by the oxalate method and 
Magnesium as Mg.P.0O,. 


SULFURIC ANDHYDRIDE. 


9. Heat 1 g. of the pigment with 10 cc. of concentrated HCl until free 
chlorine is expelled, add about 300 cc. of water and boil; filter off any insoluble 
matter and wash thoroughly with hot water, heat to boiling, and precipitate 
with BaCl, solution in the usual manner. Keep the solution hot while filtering 
off the BaSO, and wash with hot water until the washings show no lead or. 
chlorine. 


CARBON DIOXIDE. 


10. Determine carbon dioxide by the evolution method, using dilute HNO,, 
free from oxides of nitrogen. 


WATER-SOLUBLE MATTER. 


11. Weigh 2.5 g. of the pigment and transfer to a graduated 250-ce. flask, 
(add 100 cc. of water, and boil for 5 minutes. Dilute with water, let stand 
until at room temperature, make up to the mark with water, mix, and let settle. 
Filter through dry paper and discard the first 25 cc. Transfer 100 cc. of the 
clear filtrate to a weighed dish, evaporate to dryness on a steam-bath, dry in 
an oven at 105 to 110° C. to constant weight (30 minutes will usually suffice) ; 
cool and weigh. 


TINTING STRENGTH AND ADDED COLORING MATTER. 


12. Make the test for added coloring matter and tinting strength in accord- 
ance with Sections 2 and 3. 


CALCULATIONS. 


18. Calculate CrO, to PbCrO,, and SO, to PbSO, if calcium is absent. If 
CO, is present and calcium and magnesium are absent, calculate to (PbCO,),.- 
Pb(OH),. Report any residual Pb as PbO. If calcium is present, calculate 
to CaCO, if CO, is also present. If calcium and SO, are present and CO, is 
absent, calculate to CaSO,. If calcium, CO,, and SO, are present, calculate to 
CaCO, ; any residual calcium is then calculated to CaSQ,. Report zine as ZnO. 


740 Yellow, Orange, Blue, and Green Pigments 


METHODS OF ANALYSIS OF BLUE PIGMENTS. 
IRON CYANIDE BLUES. (PRUSSIAN BLUE, CHINESE BLUE, ANTWERP BLUE, 


Minor BLUE, BRONZE BLUE, STEEL BLUE.) 
The analysis of these blues, as is generally the case with pigments, does 
not necessarily give results which can be used to grade samples, the strength 
and color tests being most important. 


MOISTURBE. 

14. Heat 2 g. of the pigment at 105° C. for two hours. The loss in weight 
is reported as moisture. A “dry” Prussian blue should contain less than 7 
per cent of moisture. 

INSOLUBLE MATTER. 

15. Ignite 1 g. of the pigment in a porcelain dish at a low temperature, 
just high enough to decompose the last trace of blue, but not high enough to 
render the iron difficulty soluble in HCl. Cool, add 15 cc. of HCl and a few 
drops of bromine, cover with a watch glass, and digest on the steam bath; 
wash off cover, evaporate to a syrup, add water, boil, filter, wash with hot 
water, ignite the residue and weigh. Examine the insoluble residue for silica, 
barium sulfate, and alumina. A pure Prussian blue should show no insoluble 
residue. 

IRON AND ALUMINUM. 

16. Determine iron and aluminum in the filtrate from the insoluble matter 
by precipitation with NH,OH in the usual manner. A double precipitation is 
desirable. Ignite and weigh Fe,0,+Al1,0,, deduct Fe,O, (calculated from total 
Fe), and calculate Al,O,; to Al. 


CALCIUM. 

17. Determine calcium in the filtrate from the Fe,O,+A1,0, by precipitation 
with ammonium oxalate titrate with KMn0O,, or ignite and weigh as CaO. 
Acidify the filtrate from the calcium oxalate with HCl and dilute to a definite 
volume and mix. 

SULFURIC ACID. 

18. Determine sulfuric acid in an aliquot of the above solution as BaSO, 

in the usual manner. 


ALKALI METAL AND ALKALINE SALTS. 

19. Evaporate an aliquot of the above solution with sulfuric acid, ignite 
(treating with solid ammonium carbonate), and weigh. Determine whether 
the alkali metal is sodium or potassium and subtract the alkali metal corres- 
ponding to the sulfate (SO,) found. The remainder is alkali combined with 
the blue and is reported as Na or K. 


TOTAL IRON. 
20. Decompose and dissolve 1 g. of the pigment as under “Insoluble Matter,” 
reduce, and determine the total iron with KMnO, or K.Cr.0;,. There should 
be not less than 30 per cent, calculated on the dry pigment. 


TOTAL NITROGEN. ui 
21. Determine the total nitrogen on a 1-g. sample of the pigment by the 
Kjeldahl-Gunning Method, digesting: for at least 214 hours. The sulfuric acid 


= 


should not blacken, which would indicate organic adulteration. 


Yellow, Orange, Blue, and Green Pigments 741 


WATER-SOLUBLE MATTER. 

22. Weigh 2.5 g. of the pigment into a graduated 250-ce. flask, add 100 ce. 
of water, and boil for five minutes. Dilute with water, let stand until at room 
temperature, make up to mark, mix and let settle. Filter through dry paper 
and discard the first 25 cc. Transfer 100 ce. of the clear filtrate to a weighed 
dish, evaporate to dryness on a steam-bath, dry in an oven at 105° C. for 30 
minutes, cool, and weigh. 


TINTING STRENGTH AND ADDED COLORING MATTER. 

23. Make the test for added coloring matter and tinting strength in 
accordance with Sections 2 and 3, omitting the treatment with hot water. 
Also test the pigment with dilute acid for ultramarine blue (evolution of 
hydrogen sulfide) and carbonates (evolution of carbon dioxide.) 


CALCULATIONS. 

24. The percentage of Prussian blue may be obtained with sufficient 
accuracy for commercial purposes by multiplying the percentage of nitrogen 
by 4.4 or the percentage of iron (in the absence of other iron pigments) by 
3.03.* 


NoTE.—Some blues, e. g., Chinese blue, may contain tin salts. Others may 
contain manganese or chromium compounds. The presence of these compounds 
should be determined by a qualitative examination at least. 


METHODS OF ANALYSIS OF ULTRAMARINE : BLUE. 

An analysis is of little value for determining the quality of pure ultra- 

marines, but is useful in the identification of foreign admixtures. Practical 

tests as to the stability and compatability of the pigment in mixtures with 

other pigments, coloring power, -tint, fineness, fastness to light, etc., are more 
important than chemical analysis. 


MOISTURE. 
25. Heat 2 g. of the pigment at 105° C. for two hours, cool and weigh. 
The loss in weight is reported as moisture. 


SILICA. 

26. Treat 1 g. of the pigment in a covered dish or casserole with 30 ce. 
of HCl (1:1), heat until decomposed, wash off and remove cover, and 
evaporate to dryness on the steam-bath. Moisten with concentrated HCl and 
again evaporate to dryness, add 1 to 2 cc. of concentrated HCl, let stand about 
5 minutes, add hot water, filter and wash the insoluble matter with hot water. 
If great accuracy is desired, evaporate the filtrate to dryness, take up with 
HCl and water, filter on a second paper, wash, and add the residue to the 
main insoluble. Ignite the insoluble matter, cool and weigh. Determine SiO, 
by volatilization with H,SO, and HF. Make a qualitative examination of any 
residue that may remain. 

ALUMINA. 

27. Render the filtrate from the silica faintly alkaline with NH,OH, boil a 

few minutes, filter, wash with hot 2-per-cent NH,Cl solution, ignite and weigh 


od 


*Parry and Coste, The Analyst, Vol. 21, pp. 225 to 230 (1896). 


742 Yellow, Orange, Blue, and Green Pigments 


as Al,O,(+Fe,0,). For more accurate work, dissolve the Al(OH), precipitate 
in HCl and reprecipitate as above. 


SODIUM OXIDE. 

28. Acidify the filtrate from the Al,0O, with H,SO,, evaporate to dryness, 
ignite (finally adding solid ammonium carbonate) and weigh as Na,SO,. 
Calculate to NaeO. If calcium is present it should be precipitated with 
ammonium oxalate in the filtrate from the Al,O,, ignited and weighed as CaO, 
and the sodium determined in the filtrate from the calcium oxalate, as 
described. 

TOTAL SULFUR. 

29. Mix 1 g. of the ultramarine with 4 g. of Na.,CO, and 4 g. of Na,O, in a 
nickel crucible, cover with about 1 g. of Na.CO, and fuse, using an aluminum 
or asbestos shield to prevent the sulfur being taken up from the gas. Dissolve 
the fused mass in dilute HCl, filter and wash, if necessary (there should be 
no insoluble residue), precipitate with BaCl, and determine total sulfur e 
weighing as BaSO, Calculate to S. 


SULFUR PRESENT AS SULFATE. 

30. Dissolve 1 g. of the pigment in dilute HCl, boil to expel H,S, and filter 
if necessary; make the solution faintly alkaline, with NH,OH and just 
distinctly acid with HCl, and treat with BaCl, in the usual manner. Calculate 
BaSO, to SO, and'to §S. 


SULFUR PRESENT AS SULFIDE. 
31. Subtract the sulfur present as sulfate from the total sulfur. 


a 


METHODS OF ANALYSIS OF COBALT BLUE* 


This pigment is essentially a compound of the oxides of aluminum and 


cobalt. Certain shades of ultramarine blue are often sold under the name 
“cobalt blue.” 
MOISTURE. 
32. Heat 2 g. of the pigment at 105° C. for 2 hours. The loss in weight is 
reported as moisture. 
ALUMINA. 
33. Fuse 1 g. of the pigment with 12 to 15 g. of sodium or potassium pyro- 
sulfate, cool, digest with water and HCl, filter, and wash the residue with 
hot water. Make the filtrate up to 250 cc. in a graduated flask and mix. 


Sg J 


ee ee ae ee 


Ignite the residue, cool, weigh, and examine for SiO, and BaSO, Dilute an 


aliquot portion of the filtrate to 200 cc., add 5 g. of NH,Cl, heat to boiling, and ~ 


add dilute NH,OH till just distinctly alkaline (a few drops of 0.2-per-cent 


alcoholic solution of methyl red is recommended as indicator). Boil for one Ss 


or two minutes, filter at once, dissolve the precipitate with HCl, and reprecipi- 


tate as before. Filter, wash thoroughly with hot 2-per-cent NH,Cl (or — 


NH,NO,) solution, ignite, and weigh as AI,O,. 


CALCIUM. AND MAGNESIUM. 


34. Unite the filtrates from the A1,O,, saturate with hydrogen sulfide, filter, % 


and determine calcium and magnesium in the filtrate in the usual manner. ~ 


*“ Analysis of: Paint-and Varnish Produce ’ by C. D. Holley, p. 210 (1912). * 


Yellow, Orange, Blue, and Green Pigments 743 


vn ea nEEEEEEEEEEEIEEIEEIIEEEEIEIRIEIEI IEEE Ee 


COBALT OXIDES. 


35. Subtract the determined constituents from 100 and report the difference 
as cobalt oxides, unless a qualitative examination shows the presence of other 
substances in significant amounts. Should the pigment contain phosphoric 
acid (or arsenic acid) in more than negligible amounts, these must be removed 
before determining aluminum, calcium and magnesium.* 


METHODS OF ANALYSIS OF SUBLIMATED BLUE LEAD.{ 
TOTAL LEAD. 


36. Digest 1 g. of the sample with 15 cc. of concentrated HNO, in a covered 
beaker. Boil the solution until the brown fumes of the oxides of nitrogen 
have disappeared. Add 6 cc. of concentrated H,SO, and again boil until the 
heavy fumes of SO, are evolved. Allow the solution to cool, add 30 ce. of 
water and boil. Remove the beaker from the hot plate and allow the solu- 
tion to stand for from 3 to 4 hours. Filter the solution, washing the precipi- 
tate by decantation 3 or 4 times and allowing the bulk of the precipitate 
to remain in the beaker. Place this beaker containing the residual lead sulfate 
under the funnel used for the filtration, wash the filter paper with 75 cc. of 
a mixture consisting of 95 ec. of NH,OH (sp. gr. 0.80), 125 ec. of 80-per-cent 
acetic acid and 100 ce. of water. Follow this washing with 75 ce. of hot 
water. Boil until all PbSO, is dissolved. Dilute to 200 ce. with hot water, 
boil and titrate with standard ammonium molybdate solution, using a freshly 
prepared solution of one part of tannic acid in 300 parts of water as an out- 
side indicator. Run a blank and correct for same. The ammonium molybdate 
solution contains 8.67 g. in one liter of water and is standardized against pure — 
lead foil, pure PbO, or pure PbSQ,. 


TOTAL SULFUR. 


37. Treat 0.5 g. of the sample in a beaker with 10 cc. of water and a few 
ce. of bromine water. Boil gently until all the bromine has passed off. Dilute 
with water, add another portion of bromine water, boil, and continue the 
treatment until the sediment has become white in color. Add 8 cc. of HNO), 
evaporate the solution until the brown fumes of nitric acid have disappeared, 
dilute with water and add an excess of Na.CO;. Boil gently (covered) for 
from 10 to 15 minutes and let stand for 4 hours. Dilute with hot water, 
filter, and wash with hot water. Reject the residue. Acidify the filtrate 
(about 200 cc.) with HCl and add an excess of about 2 cc. of the acid. Boil 
and add a slight excess of 10-per-cent barium chloride solution. Let stand 
on a steam-bath about 1 hour, filter, wash with hot water, ignite, and weigh 
as BaSO,. Calculate the BaSO, to 8. 


LEAD SULFATE. 
38. On a separate sample determine the sulfate directly with Na.CO, as in 
the preceding paragraph, without any preliminary treatment with bromine 
water. 


*See “Technical Methods of Chemical Analysis.” Lunge-Keane, Vol. III, 
Part II, p. 978 (1914). 

*“The Chemical Analysis of Lead and its Compounds.” Schaeffer and 
White, pp. 22 to 24. 


744 Yellow, Orange, Blue, and Green Pigments 


LEAD SULFITE. 


39. Boil 1.5 g. of the sample with 3 g. of Na,CO,, let stand, filter, and wash 


thoroughly. To the filtrate add 38 cc. of bromine water, heat gently to oxidize 
the sulphite to sulfate, acidfy with HCl, and precipitate with BaCl, solution. 
Filter, wash, ignite, and weigh as BaSO, Deduct the amount present as 
sulfate and calculate the remainder to lead sulfite. 


LEAD SULFIDE. 
40. Deduct the sulfur present as sulfate and sulfite from the total sulfur 
and report the difference as lead sulfide. 


LEAD CARBONATE. 
41. Determine any CO, present by the evolution method, removing any 


aaeneA 7 ae 


HeS or SO, formed by means of KMnOy, or CrOs solution. Calculate to PbCO,. ~ 


LEAD OXIDE. 
42. Deduct the lead present as sulfate, sulfite, sulfide, and carbonate from 
the total lead and report the difference as lead oxide (PbO). 


ZINC OXIDE. 
43. Boil 1 g. of the sample with a solution of 4 g. of NH,Cl in 30 ce. of 


water plus 6 cc. of concentrated HCl. Dilute to 200 cc. with hot water, add 


2 ee. of a saturated sodium thiosulfate solution, and titrate with a standard 
solution of potassium ferrocyanide, using a 5-per-cent solution of a uranium 
nitrate as an outside indicator. Report as ZnO. 


CARBON AND VOLATILE MATTER. 
44. Ignite a weighed portion of the sample in a partially covered crucible 
at a low red heat for 2 hours, cool, and weigh. Report the loss in weight 
as carbon and volatile matter. 


METHODS OF ANALYSIS OF GREEN PIGMENTS. 
( CHROME GREEN) 


A pure chrome green should contain only Prussian blue and pure chrome ~ 


yellow. A microscopic examination should be made to determine whether the 
green is a combined precipitation product, which is of the greater value, or 


one mixed after separate precipitation. A good green will show the presence ~ 


ony . ad sarah ee ee ee 
iain eel PRON A AS oT Se RY 


Ae Ati Sehr olay pes 


of green and blue particles, while a poor green will show yellow and blue ~ : 


particles mixed with green. 
MOISTURE. 


45. Heat 2 g. of the pigment at 105° C. for two hours. The loss in weight — 


is reported as moisture. 
INSOLUBLE MATTER. 


46. Heat gently 1 g. of the pigment in a small porcelain dish until the blue . 


color has been decomposed. The heating should be carried out very carefully 
so as not to render the iron difficulty soluble. (With some very pure chrome 
greens it may be advantageous to mix the sample with 2 to 5 times its weight 


of pure barium sulfate before igniting.) Let cool, transfer to a beaker, and 


determine insoluble matter as outlined in Section 5 for Yellow Pigments. 


LEAD. 


47. Determine lead in the filtrate from the above as outlined in Section — 


6 for Yellow Pigments. 


Yellow, Orange, Blue, and Green Pigments 745 


IRON, ALUMINA AND CHROMIUM. 
48. Determine iron, aluminum and chromium in the filtrate from the PbS 
as outlined in Section 7 for Yellow Pigments, making a double precipitation. 


ZINC, CALCIUM, AND MAGNESIUM. 
49. Determine zinc, calcium and magnesium in the filtrate from the iron, 
aluminum and chromium determination as outlined in Section 8 for Yellow 
Pigments. 


CARBON DIOXIDE. 

50. Determine carbon dioxide by the evolution method, using dilute HNO, 
ast) 

SULFURIC ANHYDRIDE. 

51. Heat gently 1 g. of the pigment as in Section 46, cool, transfer to a 
beaker, add 30 cc. of concentrated HCl, cover, and heat on a steam-bath for 
about 380 minutes (in some cases, the iron compounds will go into solution 
more readily by letting the solution stand for some time at room temperature 
and then heating). Wash off cover, add 50 cc. of boiling water, boil for five 
minutes, filter, render the filtrate faintly alkaline with NH,OH, then slightly 
acid with HCl, heat to boiling, and precipitate with BaCle (15 ec. of 10-per-cent 
solution) in the usual manner, boiling about ten minutes. Filter, wash with 
hot water, ignite, and weigh the BaSQ,. 


NITROGEN. 
52. Determine nitrogen on a 1-g. portion of the pigment by the Kjeldahl- 
Gunning Method, digesting for at least 214 hours. 


WATER-SOLUBLE MATTER. 

53. Weigh 2.5 g. of the pigment into a graduated 250-ce. flask, add 100 ce. 
of water, and boil for five minutes. Dilute with water, let stand until at 
room temperature, make up to the mark, mix, and let settle. Filter through 
dry paper and discard the first 25 cc. Transfer 100 ce. of the clear filtrate to 
a weighed dish, evaporate to dryness on a steam-bath, dry in an oven at 
105° C. for 30 minutes, cool and weigh. 


TINTING STRENGTH AND ADDED COLORING MATTER. 
54, Make the test for added coloring matter and tinting strength in accord- 
ance with Sections 2 and 3. Also test the pigment with dilute acid for the 
presence of ultramarine blue (evolution of hydrogen sulfide). 


Hickson’s Peroxide Method for Chrome Green Analysis. 
K. F. Hickson of the Bureau of Standards has studied the 
analysis of chrome green pigments and his conclusions are 
published in Scientific Section Circular No. 294. Several of 
his recommendations have been embodied in the A. S. T. M. 
procedure given above, the most important being the use of 
Na2O2 containing at least 90 per cent of the reagent. He also 
recommends the addition of peroxide to a cold solution, 10- 
12° C. The writer has also found these precautions of 
value. 


746 Yellow, Orange, Blue, and Green Pigments 


ee ee ee eee ene ee a a 


Brown’s Method for Chrome Green Analysis. A. F. Brown 


in a private communication has submitted his methods for 
the analysis of chrome green either pure or reduced. It is 


believed that these methods are well worth consideration. — 


They are given below: 


Heat 2 grams of pigment at 110° C. for two hours. - Loss in ~ 


weight is reported as moisture. 


1 gr. pigment is weighed into a 250 ce. Pyrex beaker, cover ~ 
with watch-glass, decompose the pigment by placing beaker : 
on an electric hot- plate (about 250° C.) until the color is — 
destroved. (With pure or C. P. colors (to prevent ignition) — 
add 2 to 5 grams of dry Na.CO, mixing thoroughly with stir- 
ring rod). (Cool beaker, carefully treat with about 25 cc. conc 
HCl and a little KC1O;, boil about 5 minutes, dilute to 100 ee. ~ 
and filter off any insoluble matter, washing thoroughly with ~ 
hot water. This insoluble matter combined with any BaSOs — 
found below is ignited in a platinum crucible, cooled and — 
weighed. Add about 10 grs. Na,CO,-K,CO; (1-1) heat to a_ 
clear fusion, cool, digest with water, filter off any insoluble © 
matter washing with hot water containing a little Na.CO;;_ 
evaporate alkaline filtrate to small volume. Dissolve insolu-— 
ble matter on paper (also in beaker and crucible) in hot ~ 
dilute HCl and precipitate the Ba with H2SO, (1:1). Digest ~ 


BaSoO,, filter, ignite and weigh. Evaporate this acid filtrate 


to small ole and eapetiiis combine with the alkaline fil-@ 


trate from fusion, acidify with HCl if necessary, evaporate — 


as dry as possible, take up with dilute HCl, filter off any SiOs — 
and determine Al and Mg in filtrate. If Al and SiO. are pres- — 


ent calculate to clay, using the theoretical formula, Al.O;.- 


2810..2H.O. The Be found represents the BaSO, ‘present 


probably as barytes. 


Nearly neutralize insoluble matter filtrate (or original solu-— 


tion) with NH,OH, dilute to about 300 ec. and pass in H, S 
until all Pb is precipisated: Filter off the PbS on a Gooch, - 
washing thoroughly. Transfer PbS and asbestos to originally 


beaker, pour hot (1-1) HNO; through Gooch into the beaker — 


with the PbS to dissolve any PbS on “the crucible. Digest PbS — 
in beaker until black PbS is all dissolved. Filter off the 
asbestos and sulfur, through a thin mat of asbestos on the - 
Gooch. Add (1-1) H2S80. to ‘the clear hot filtrate and evaporate — 
to SOs fumes. Cool, dilute to about 100 ce., let stand about an ~ 


hour, filter on Gooch, wash with dilute HS80a, dry, ignite and 


weigh as PbSOs. 


Yellow, Orange, Blue, and Green Pigments 747 


ey 


Add about 10 ee. (1-1) HeSOs to above PbS filtrate, digest 
about an hour to expel H.S and to precipitate any BaSQ, dis- 
solved from the insoluble matter. If a precipitate is obtained 
at this point, filter off, and combine with the insoluble matter 
as mentioned above. The filtrate is made slightly ammoniacal; 
digest on hot-plate until hydroxides separate clear; filter, 
wash with hot water. Determine any Ca, Mg or Zn in the 
filtrate. Redissolve the hydroxides on fe filter paper by 
pouring through about 25 ce. boiling (1-1) HCl, catching 
the filtrate in a 250 ce. volumetric flask, further Wash the filter 
paper with hot dilute HCl until clean, finish with hot water. 
Cool the flask and dilute to the mark. Pipette out two 100 ce. 
portions of this solution. Make one portion slightly ammo- 
niacal, digest, filter, ignite and weigh as total oxides. Make 
the other portion slightly alkaline by adding small pieces of 
e.p. NaOH (sticks), cool thoroughly, add about iets e Na Ol 
heat to boiling and boil a few minutes to remove the H.O.. 
Filter off the Fe(OH)s, washing with hot water, evavorate the 
filtrate containing the chromium in about 100 ce, Redissolve 
the Fe(OH)s by pouring 25 ce. boiling (1-1) HC! on to the filter 
paper, catching the filtrate in the original beaker. Heat the 
Fe solution nearly to boiling and add from a pipette, drop by 
drop, some 10 per cent SnCl. until the solution becomes prac- 
tically colorless. Adda few drops in excess. Cool thoroughly, 
add about 15 ec. of saturated SnCl., a hazy, white precipi- 
tate HgCl should appear after a little stirring, if not, not 
enough SnCl, was added. Add about 10 ec. H.SO,-H,PO, 
(1-1) and four drops of diphenylamine indicator (1 gram salt 
in 100 ee. conc. H.8O,). Titrate with N/10 K.Cr20; to a deep 
blue (starch-iodine color), calculate to FeO; and iron blue 
(Fe X 3.03). Acidify the chromium solution with HeSOs- 
H;PO, (1-1), add an excess of N/10 (NH,). Fe(SO,)2.6H2O and 
four drops diphenylamine indicator, titrate back with 
N/10 KeCr20,. Run a blank on the N/10 (NH,)> Fe (SO,) 6H20. 
Calculate results to Cr,O3 and PbCrOs. The chromium may 
also be determined by adding about 20 ce. of 10 per cent 
KI to the alkaline chromium solution, in an iodine flask, mak- 
Ing acid with cone. HCl, and after ten minutes, titrating back 
with N/10 Na.S.O, using starch solution as an ee Rioe. The 
sum of the Fe,O3 and Cr.Os found, subtracted from the total 
oxides gives the Al.Os, if any. 


Ignite 1 gram sample as indicated under insoluble matter, 


dissolve in about 10 ce. cone. HCl by boiling, dilute to about 
100 ce., filter off any insoluble matter while hot, washing with 


748 Yellow, Orange, Blue, and Green Pigments 


lene re : 


hot water. Heat to boiling, add about 15 ee. of 10 per cent — 
BaCl, and digest about 2 hours, better overnight if SOs is — 
small. Filter BaSOs hot, washing thoroughly with hot water. — 
This method is probably not very accurate in the case of a © 
reduced green, especially when barytes and China Clay have_ 
been used as extenders and in the presence of iron salts since — 
under these conditions a small amount of the extenders will 
¢o into solution and may be thrown out on dilution or on add-~ 
ing the BaCl. 

Digest a 1 gram sample in about 200 ce. hot water (about — 
85° C.) for about 2 hours, filter on Gooch, dry at 110° C., cool 
and weigh. Loss in weight, corrected for the moisture found 
above, represents the water soluble salts. 

Digest a 1 gram sample in about 200 ee. hot water containing 
10 ce. glacial acetic acid for about 2 hours. Filter on Gooch, 
nearly neutralize the hot acetic acid filtrate with NH,sOH, add 
an excess of K,Cr.0O, solution, digest until PbCrO, settles” 
clear. Filter on Gooch, wash the precipitate thoroughly with — 
hot water and finally with a little aleohol. Dry at 110° C., cool — 
and weigh. If CO, is present in the pigment, as shown by an 
effervescence when some is sprinkled upon acid in a watch- 
glass, and Ca and Mg are absent, calculate the acetic soluble 
Pb to Pb(COs)..Pb(OH).. If no COse is present the acetic 
soluble Pb may represent the PbO of a basic PbCrOs or other 
acetic acid soluble lead compound. ¥ 

Calculate CrO3 to PbCrOs, and SOs to PbSOs if Ca is absent. 
If CO, is present and Ca and Mg are absent, calculate to 
(PbCOs)2. Pb(OH)»2. Report any residual Pb. as checked 
by the acetic soluble determination, as PbO. If Ca is present, 
caleulate to CaCOs if COz is also present. If Ca and SOs: are 
present and COz is absent, calculate to CaSOs. If Ca, CO. and 
SOs are present, calculate to CaCOs; any residual Ca is then 
calculated to CaSOs. Report Zn as ZnO. Fe X 3.03 (in the © 
absence of other iron pigments) represents the iron blue 
present. 


Zinc Chromate Analysis. The insoluble matter may be 
determined as on chrome greens (page 737). 


Zinc.—The filtrate from the insoluble matter is made alka- 
line with NaOH and then treated with H2S. The ZnS is filtered 
off, dissolved in HCl and the Zn determined by any desirable 
method. 


Chromium.—tThe filtrate from the ZnS precipitate contains 
the chromium, which may be determined as in chrome greens. 


Yellow, Orange, Blue, and Green Pigments 749 


The solution is first acidified with HCl and boiled to remove 
the H2S, after which the procedure on page 737 may be fol- 
lowed. 


Chromic Oxide Green Analysis. The important determi- 
nation on this pigment is the chromium oxide content, the 
chromium being determined as on page 737. The pigment is 
brought into solution by the method of Scott.* 0.5 gram of pig- 
ment is fused gently in an iron or nickel crucible with 2 or 3 
grams fresh Na.O, for 15 minutes. 1 gram of NazOz is added 
and the fusion continued for 5-10 minutes longer. The melt is 
digested in 100 ec. of boiling water for 10-15 minutes and 5 
grams of (NH,).CO; are added to neutralize the free alkali. 
The solution is filtered hot and the chromium in the filtrate 
determined. 


Miscellaneous Pigments. The methods given above cover 
practically all commonly used pigments found in commercial 
paints. There are, however, a number of rare pigments used 
to a small extent in artists’ colors. Among these may be 
mentioned blues containing arsenates or phosphates, Guignet’s 
green, green earth, copper greens and cobalt greens. The 
methods for the analysis of many of these are discussed in| 
“The Analysis of Pigments, Paints, and Varnishes’’ by Fox 
and Bowles.t 


AS.T.M. TENTATIVE SPECIFICATIONS FOR PURE CHROME GREEN. 


1. These specifications cover what is commercially known as pure chrome 
green. The pigment may be purchased in the dry form or ground in oil or in 
japan to form a paste. 


I. MANUFACTURE. 

2. (a) Dry Pigment.—The pigment ‘shall be a precipitated mixture of lead 
chromate and iron ferro and ferricyanide blue, with or without other insoluble 
compounds of lead. 

(b) Paste in Oil.—The paste in oil shall be made by thoroughly grinding 
the specified pigment with pure raw or refined linseed oil. ; 

(c) Paste in Japan.—The paste in japan shall be made by thoroughly 
grinding the specified pigment with high-grade grinding japan. 


II. PROPERTIES AND TESTS. 

3. (@) The mass color and character of the tint formed by mixture with 

a white pigment shall be the same as, and the strength not less than, that 
of a sample mutually agreed upon by buyer and seller. 


* Scott. Standard Methods of Chemical Analysis, p. 157. 
TD. Van Nostrand, 1927. 


750 Yellow, Orange, Blue, and Green Pigments 


(b) Dry Pigment.—The dry pigment shall meet the following requirements: 


Percentage of total lead present in the form of chromate, mini- 


TUM) ©. fc oe bc eb oe wre ne Wak 0-0 ole wim 5 lal i nae tet ee lagen 70 
Total impurities, maximum, per CeNt.......-- seer eeeeeeeeceres 3 
Coarse particles (total residue retained on a No. 325 screen), 

MAXIMUM, PEL CEN 1... eee ee sere e eee reeeerereerssescerers 


(c) Paste in Oil.—The paste as received shall not be caked in the container — 
and shall break up readily in oil to form a smooth paint of brushing con- | 
sistency. It shall mix readily in all proportions, without curdling, with lin- 
seed oil, turpentine, or volatile mineral spirits, or any combination of these — 
substances. The paste shall meet the following requirements: 


Pigment, minimum, per Cent... -... eee eeeeee cee ere creer recres 70 

Linseed oil, maximum, per CeNt...... cee eee eee rc ere eeceerarenes 30: 

Coarse particles and skins (total residue retained on a No. 325 
screen), maximum, per cent of the pigment..........-+++++- 1.5 


(d) Paste in Japan.—The paste as received shall not be caked in the con- — 
tainer and shall break up readily in turpentine to form a smooth paint of © 
brushing consistency that will dry within one hour to a hard, flat coat that 
can be varnished within 5 hours of the time of application without streaking — 
or bleeding. The paste shall meet the following requirements : 


Pigment, minimum, per CEN... 1... eee eer cere cere rece ree eneeees 65 

Vehicle (japan), maximum, per CeNt....-.+eeseeeeereeesereess 35 

Coarse particles and skins (total residue retained on a No. 3825 
screen) maximum, per cent of the pigment.............-.-. 1.5 : 


Non-volatile matter in vehicle, minimum, per cent of the vehicle 40 


4. One sample shall be taken at random from each lot of 1000 packages : 
or less. If the packages are of such size that 1000 packages amount to more q 
than a carload, one sample shall be taken at random from each ecarload. 


A.S.T.M. TENTATIVE SPECIFICATIONS FOR REDUCED CHROME : 


: xf 


GREEN 


1. These specifications cover what is known commercially as reduced — 
chrome green, also known as grinders green. The pigment may be purchased — 


in the dry form or ground in oil or in japan to form a paste. 


I. MANUFACTURE. f 

2. (a) Dry Pigment—The pigment shall be a mixture of lead chromate — 
and iron ferro and ferricyanide blue, with or without other insoluble com- i 
pounds of lead, precipitated on a base of barium sulfate or insoluble siliceous i: 
material or any mixture thereof. a 
(b) Paste in Oil—The paste in oil shall be made by thoroughly grinding — 
the specified pigment with pure raw or refined linseed oil. : i 
(c) Paste in Japan—The paste in japan shall be made by thoroughly | 
grinding the specified pigment in high-grade grinding japan. 


i 


II. PROPERTIES AND TESTS. ‘ 
8. («) The mass color and character of the tint formed by mixture with = 


Yellow, Orange, Blue, and Green Pigments 751 


a white pigment shall be the same as, and the strength not less than, that of 
a sample mutually agreed upon by buyer and seller. 
(b) The dry pigment shall meet the following requirements: 


MAXIMUM MINIMUM 
Sum of the barium sulfate and insoluble. siliceous 


BRIA OTIGONG hoc os fcc. hes sch sed vuneceseaces 80 
Color (total of insoluble lead compounds: and iron 

2 SESS ol 20, is ee itis 20 
Percentage of total lead present in the form of chromate .... TO 
Total calcium oxide in any form soluble in acid, per 

eR eae eel yas eo ive a's 8 sb geace’s coe as eccos ds 1.0 
Coarse particles (total residue retained on a No. 325 

AMES TENE re eae, fopice ao el'x xxl! «6 0.4 te oe: wie wa adelele's 1.5 


(c) Paste in Oil.—The paste as received shall not be caked in the container 
and shall break up readily in oil to form a smooth paint of brushing con- 
sistency. It shall mix readily in all proportions without curdling, with linseed 
oil, turpentine, or volatile mineral spirits, or any combination of these sub- 
stances. The paste shall meet the following requirements: 


CREDIT FOr! CNL oi. se kc oes oa ares a wt vie ce cae an come SO 

Pee AMIN Per CONt. 66s. ck ck kh ae sw ece debian 20 

Coarse particles and skins (total residue retained on a No. 325 
screen), maximum, per cent of the pigment................. 2.0 


(d) Paste in Japan.—The paste as received shall not be caked in the con- 
tainer and shall break up readily in turpentine to form a smooth paint of 
brushing consistency that will dry within one hour to a hard flat coat that can 
be varnished within 5 hours of the time of application without: streaking or 
bleeding. It shall meet the following requirements: 


PEPER NINAITIN’ PCT © CONG 5:0. 5:0 c cos Sade we ac ce weneccvecen bes T5 

Peete (japan), Maximum, per cent...........0. ccc ce see we ee’ 25 

Coarse particles and skins (total residue retained on a No. 325 
meen ena SITUIM PET CONG. <6. 5 oa oss eleeis eo oo bo otve wale vedas 2.0 


Non-volatile matter in vehicle, minimum, per cent of the vehicle 40 


4. One sample shall be taken at random from each lot of 1000 packages 
or less. If the packages are of such size that 1000 packages amount to more 
than a carload, one sample shall be taken at random from each carload. 


A.S.T.M. TENTATIVE SPECIFICATIONS FOR CHROME OXIDE GREEN 

1. These specifications cover the pigment commonly known as chrome oxide 
green. The pigment may be purchased in the dry form or ground in oil to 
form a paste. 

MANUFACTURE. 

2. (a) Dry Pigment.—The dry pigment shall consist of practically pure 
sesqui-oxide of chromium (Cr,0O,) without any admixture. 

(6) Paste.—The paste shall be made by thoroughly grinding the specified 
pigment in pure raw or refined linseed oil. 


PROPERTIES AND TESTS. 
’ 5. (@) The mass color and character of the tint formed by mixture with 
a white pigment shall be the same as, and the strength shall be not less than 
that of a sample mutually agreed upon by the buyer and seller. 


752 Yellow, Orange, Blue, and Green Pigments 


(b) Dry Pigment.—The dry pigment shall conform to the following Ps 
requirements | ~ 


Total chromium (ealeulated as Cr ,O), minimum, per cent,..... 97,0 
Coarse particles (total residue retained on a No, 826 screen), 
maximum, per CODTs saa he seeee eeeaeeveeeeee eee eeeoe eevee eeeeenen @ . 


(¢) Paste Phe paste as received shall not be caked in the container and “ 
shall break up readily in off to form a smooth paint of brushing consistency. % 
It shall mix readily, in all proportions, without curdling, with linseed oil, 4 
turpentine or volatile mineral spirits, or any mixtures of these substances, — 
The paste shall conform to the following requirements ; ‘ 


MAXIMUM MINIMUM 


Pigment, per cent..... SOPTURenETT Its) 8 
Linseed oll, per CeNt....esee6. ose 0:90 65. . 
Coarse particles and aking (total ‘residue retained on 

a No, 825 sereen, based on plement), per cent.... 2.5 « 


4, One sample shall be taken at random from each lot of 1000 packages — 
or fraction thereof, Tf the packages are of such size that 1000 packages } 
amount to more than a carload, one sample shall be taken at random from 
each eartoad, 


AS'R.M. TENTATIVE SPECIFICATIONS FOR ULTRAMARINE BLUE 
1, These specifications cover the pigment commonly known as ultramarine — 
blue, It may be purchased in the dry form or ground in oil or in japan to | 
form a paste, 
MANUFACTURER, 

2, (a) Dry Pigment.—The dry pigment shall be a manufactured blue | 
approximating the composition of natural lapis lazuli, It shall be finely — 
ground and of good blue color and free from admixtures of other substances, — 
(0) Paste in Oil——The paste in oil shall be made by thoroughly grinding ‘ 
the specitied pigment in pure raw or refined linseed oil, s 
(¢) Paste in Japan.—The paste in japan shall be made by thoroughly E 
grinding the specified pigment in high-grade grinding japan, . 


PROPERTIES AND TESTS, 

8. Gi) The mass color and character of the tint formed by mixture with — 

a white plement shall be the same as, and the strength not less than, that of — 
a simple mutually agreed upon by the buyer and seller, b 
(v0) Dry Pigment.—The dry pigment shall conform to the following — 
requirements | 


Coarse particles (total residue retained on a No, 825 sereen), 
maximum, per CONE c's a's 0 4 0-0) ba eu bb 8k bent ere er gee cn . 


(c) Paste in Oil—The paste in ofl as received shall not be caked in the 
container and shall break up readily in ofl to form a smooth paint of brushing - 
consistency, It shall mix readily in all proportions, without curdling, with — 
Linseed oll, turpentine or volatile mineral spirits, or any mixture of these — 
substances, The paste shall conform to the following requirements; } 


Yellow, Orange, Blue, and Green Pigments 753 


MAXIMUM MINIMUM 


POU MCOTER Ey ce yok eas ce cence Cteccseces’e sage 70.0 
PES PTOLICEIIGS si dels rece es ce ceedsseecceeuns 30.0 
Moisture and other volatile matter, per cent......... 0.7 
Coarse particles and skins (total residue retained on a 
No. 325 screen), per cent....... Pete ats ataiets Been ate 1.5 


(d) Paste in Japan.—The paste as received shall not be caked in the 
container and shall break up readily in turpentine to form a smooth paint of 
brushing consistency, that will dry within one hour to a hard flat coat that 
can be varnished within five hours of the time of application without streaking 
or bleeding. The paste shall conform to the following requirements : 


MAXIMUM MINIMUM 


ETRE OE MOOG Solas siae sla scl c se cc ccesveceave iy 70.0 
Pemrroree JAAN) PEL CENL. oe pecs cc cee nncess 30.0 
Coarse particles and skins (total residue retained on a 

Rime esc reen ). Per CONG. «6. es eee e ce wee ees aa) 
Non-volatile matter in the vehicle, per cent of the 

SENG hei als ga ielg ¢ 4 pte \sj0 ¢:0,v'b.0i0'0 wee eee eee. Se 40.0 


Nore.—The physical properties and tests of ultramarine blue, particularly 
the tinting strength, are considered a better measure of value than the per- 
centage of chemical constituents. 


4. One sample shall be taken at random from each lot of 1000 packages 


or fraction thereof. If the packages are of such size that 1000 amount to 
more than a carload, one sample shall be taken at random from each carload. 


A.S.T.M. TENTATIVE SPECIFICATIONS FOR 
CHROME YELLOW 


1. These specifications cover the pigments commonly known as lemon 
chrome yellow, medium chrome yellow, and orange chrome yellow. The pig- 
ment may be purchased in the dry form or ground in oil, or in japan, to form 
a paste. 

I. MANUFACTURE. 

2. (a) Dry Pigments.—The dry pigments shall be chemical precipitates 
consisting of normal or basic lead chromates or mixtures of these with or 
without admixtures of other insoluble compounds of lead, but without any 
other admixtures. 

(b) Pastes in Oil.—The pastes in oil shall be made by thoroughly grinding 
the specified pigments with pure raw or refined linseed oil. 

(c) Pastes in Japan.—The pastes in Japan shall be made by thoroughly 
grinding the specified pigments in high-grade grinding japan. 


II. PROPERTIES AND TESTS. 
3. (a) The mass color and character of the tint formed by mixture with 
a white pigment shall be the same as, and the strength not less than, that of 
a sample mutually agreed upon by buyer and seller. 


754 Yellow, Orange, Blue, and Green Pigments 


(vb) The dry pigments shall meet the following requirements : 


Total matter soluble in water, maximum, per cent...... < Saree 0.5 
Total of all substances other than insoluble compounds of lead, 
MAXIMUM, Per CONE. 6s. «obs. ao = w oie Wie eleneeen mene aie sc loge feat 
Organic. colors of lakes. 62.6... 666 sess wine neler None 
Coarse particles and skins (total residue retained on a No. 325 
screen), maximum, per cent of the pigment.........5..... 


(c) Paste in Oil—The pastes as received shall not be caked in the con- 
tainer and shall break up readily in oil to form a smooth paint of brushing 
consistency. They shall mix readily in all proportions without curdling, with 
linseed oil, turpentine, or volatile mineral spirits, or any combination of these 
substances. 


The pastes shall meet the following requirements: 


Pigment, minimam, per cent... ..... >. ssn vi vlads Skee ones {eeeto 
Linseed oil, maximum, per cent... . 0% «ss. ose anemeeene dle w kone BU eee 
Water and other volatile matter, ‘maximum, per CONT isa es eae 0.7 
Coarse particles and skins (total residue retained on a No. 325 
screen), maximum, per cent of the pigment................ 1.5 


(d) Paste in Japan.—The pastes as received shall not be caked in the 
container and shall break up readily in turpentine to form a smooth paint 
of brushing consistency that will dry within one hour to a hard flat coat that 
can be varnished within five hours of the time of application without streaking 
or bleeding. They shall meet the following requirements : 


Pigments, minimum, per cent......%. . 2. sss sels wie ets a eee 70 
Vehicle (japan), maximum, per Cent. <2...) .05 066 eee ni Savard cau 
Coarse particles and skins (total residue retained on a No. 325 
screen), maximum, per cent of the pigment................. 1.5 
Non-volatile matter in the vehicle, minimum, per cent of the 
bc 00 CC) (: re rrr Sr sis aa epee eas ce 


4. One sample shall be taken at random from each lot of 1000 packages 
or less. If the packages are of such size that 1000 packages amount to more 
than a carload. one sample shall be taken at random from each carload. 


A.S.T.M. TENTATIVE SPECIFICATIONS FOR 
PRUSSIAN BLUE 


1. These specifications cover the pigment commonly known as Prussian 
blue, Chinese blue, or iron blue. It may be purchased in the dry form, or 
ground in oil or in japan to form a paste. 


MANUFACTURE. 


. (a) Dry Pigment.—The dry pigment shall be the blue product formed 
by i reaction of solutions of iron salts with ferro or ferricyanide solution. 
It shall not be admixed with any other substance. 

(6) Paste in Oil—The paste in oil shall be made by thoroughly grinding 
the specified pigment in raw or refined linseed oil. 

(¢c) Paste in Japan.—The paste in japan shall be made by thoroughly 
grinding the specified pigment in high-grade grinding japan. 


Yellow, Orange, Blue, and Green Pigments 755 


PROPERTIES AND TESTS. 
3. (@) The mass color and character of the tint formed by mixture with 
a white pigment shall be the same as, and the strength not less than, that of a 
sample mutually agreed upon by the buyer and seller. 
(6) Dry Pigment.—The dry pigment shall conform to the following 
requirements : 


Total matter soluble in water, MAXHOUM Her cent. = Ase. ss oc. 0.5 
Coarse particles (total residue retained on a No. 325 screen), 
ee rns) i Cl a ee le 1.0 


(c) Paste in Oil—The paste as received shall not be caked in the con- 
tainer and shall break up readily in oil to form a smooth paint of brushing 
consistency. It shall mix readily in all proportions, without curdling, with 
linseed oil, turpentine or volatile mineral spirits, or any mixture of these 
substances. The paste shall conform to the following requirements: 


MAXIMUM MINIMUM 


ME Ces bs chek See eee. ee eo: 48.0 
Re OEP ICON ops. ws ccc cosine es odccncisccne. 52.0 ee 
Moisture and other volatile matter, per cent........ 0.7 
Coarse particles and skins (total residue retained on 

Pa Croeo sereen), per Cent... 6... peso cece eee. 19 


(d) Paste in Japan.—The paste as received shall not be caked in the con- 
fainer and shall break up readily in turpentine to form a smooth paint of 
brushing consistency, that will dry within one hour to a hard flat coat that 
can be varnished within five hours of the time of application, without streak- 
ing or bleeding. The paste shall conform to the following requirements : 


MAXIMUM MINIMUM 


MEO CT ECON Cs oo oooh vs cee cow nk ws eens pee. 48.0 
Meetreew gana), per Cent... 2 ccd lec ceeccccecscn 52.0 ie 
Coarse particles and skins (total residue retained on 

Se Omoco SCreen) per Cent... . sss cele ccc eec acne ts ea 
Non-volatile matter in the vehicle, per cent of the 

Sh vai Ek Eis Se Cl cn a one 40.0 


Note.—The physical properties and tests of Prussian blue, particularly 
the tinting strength. are considered a better measure of value than the per- 
centages of chemical constituents. 


4. One sample shall be taken at random from each lot of 1000 packages 
or fraction thereof. If the packages are of such size that 1000 packages 
amount to more than a carload, one sample shall be taken at random from 
each carload. 


CHAPTER XLIII 
ANALYSIS OF BLACK PIGMENTS 


The black pigments include those which contain carbon as 
their essential constituent. The introduction of asphaltic and 
coal-tar mixtures complicates their chemical analysis. Min- 
erals such as slate containing a substantial percentage of 
carbon, natural and precipitated black oxides of iron are also 
used to some extent in the industry. 


The analysis of the simple black pigments may Be cog. 
out in the following way: 


Moisture.—Dry 2 grams at 105° C. for two hours. 


Oil.— Extract 2 grams, with ether in a fat-extraction appa- 
ratus. 


Carbon.—Determine the carbon by difference after deter- 
mining the moisture, oil and ash. For an exact determination 
of carbon make a combustion test, absorbing the carbon 
dioxide in soda-lime or caustic potash as usual. 


The carbon in a paint pigment mixture may also be deter- 
minded directly. The pigment is first extracted with a solvent. 


It is then treated with hydrochloric acid and the mixture is — 


boiled to decompose any carbonates present, such as lead 
carbonate, calcium carbonate, etc. The contents of the beaker 
are then evaporated to dryness and the free carbon deter- 
mined by combustion. Another direct method of determining 
carbon present with other pigments is now being studied in 
this laboratory. It consists in floating the pigment in a 
liquid, the density of which is slightly greater than that of a 
carbon pigment. It is possible that this method may even 
show a separation of lampblack which has a gravity of 1.8 and 
graphite which has a specific gravity of 2.4. An analogous 
method is already in use for mineralogical work and suitable 
liquids for this purpose are described by John D. Sullivan in 
Bureau of Mines Technical Paper No. 381. 


Ash.—Ignite 2 grams to a bright red heat until all the car- 
bon is driven off. If graphite is present, the ignition should be 
carried out with the aid of oxygen. Should carbonate be pres- 
ent, mix the ash with a small amount of ammonium carbonate 


a 


Analysis of Black Pigments 757 


and again ignite, thus reconverting to carbonate any oxide 
which may have been formed. 


Analysis of Ash.—The ash is boiled. with concentrated HC] 
and the insoluble residue determined in the usual manner. The 


filtrate is examined for calcium, magnesium and phosphorie 
acid. 


Calculate the magnesium to phosphate, any residual phos- 
phoric acid to calcium phosphate and any residual calcium to 
carbonate. In the case of graphite and black oxide of iron, 
the analysis of the ash is carried out as with iron oxide pig- 
ments in Chapter XLIV. 


Gases.—Black pigments such as lamp or gas blacks may con- 
fain as high as 15 per cent absorbed or adsorbed gases. High 
vacuum is necessary to free such gases from the pigment. 


A.S.T.M. STANDARD SPECIFICATIONS FOR LAMPBLACK 


I. MANUFACTURE. 

1. These specifications cover the pigment commonly known as lampblack. 
The pigment may be purchased in the dry form, or ground in oil or in japan 
to form a paste. 

2. (@) The dry pigment shall be made by burning oils or tars in such a 
manner as to form a deposit of carbon or soot. The pigment shall be high 
grade in every respect, shall be free from oil, greasy matter and from admix- 
ture of any other substance. 

(b) Paste in Oil.—The paste in oil shall be made by thoroughly grinding 
the specified pigment with pure raw or refined linseed oil. 

(¢c) Paste in Japan.—The paste in japan shall be made by thoroughly 
grinding the specified pigment in high-grade grinding japan. 


II. PROPERTIES AND TESTS. 
3. (a) The color and tone shall be equal to, and the tinting strength not 
less than, that of a Sample mutually agreed on by buyer and seller. 


(b) Dry Pigment.—The dry pigment shall meet the following require- 
ments: 


Coarse particles retained on a standard No. 325 screen, maxi- 


I er So al are 5 cele poe ae ee Ging beens Gane cous 1.0 
MEMEO Cr er Cents see Us Poe eek oe eo eee Lo 
Benzol extract (which must be colorless), maximum. per cent.. 0.5 
Tone when diluted with zine oxide............ --.-..Clear-blue-gray 


(c) Paste in Oil.—The paste as received shall not be caked in the container 
and shall break up readily in oil to form a smooth paint of brushing con- 
Sistency. It shall mix readily in all proportions without curdling, with linseed 
oil, turpentine, or volatile mineral spirits, or any combination of these sub- 
stances. The paste shall meet the following requirements: 


758 Analysis of Black Pigments 


MAXIMUM MINIMUM 


Pigment, per Cent........-sescecececoresersenucens Pe 25 
Linseed Oil, per CeNt... 20. 60. ee ce tee ses 5 5s 6 eis 75 
Material volatile at 105° C......- 2. eee eee ree neeees 0.7 
Coarse particles and skins left on a No. 325 screen 
(per cent of the dry pigment) ....--++++++eeerees 


(d) Paste in Japan.—The paste as received shall not be caked in the con- 
tainer and shall break up readily in turpentine to form a smooth paint of © 
brushing consistency that will dry within one hour to a hard, flat coat. It 
shall meet the following requirements: 


MAXIMUM MINIMUM 


Pigment, per cent... ..0....6+s0cs ee +0 neem seen : 25 
Vehicle, per Cent. ..... 02 .csncensectcccsessecevesees 75 -s 
Coarse particles and skins retained on a standard 

No. 325 screen (per cent of the dry pigment)..... 1.0 
Non-volatile matter in the vehicle, per cent of the 

vehicle ccc eccas cece cee es @ + 6 viele nip eleeie Ste Meee 40 


4. One sample shall be taken at random from each lot of 1000 packages 
or less. If the packages are of such size that 1000 packages amount to more 
than a carload, one sample shall be taken at random from each carload. 


ASTM. STANDARD SPECIFICATIONS FOR BONE BLACK 


1. These specifications cover the pigment commonly known as bone black, 
ivory black or drop black. It may be purchased in the dry form, or ground 
in oil or in japan to form a paste. | 


I. MANUFACTURE. 
2. (a) Dry Pigment.—The dry pigment shall be made by the calcination 
of bones and shall be unmixed with any other substance. 
(b) Paste in Oil.—The paste in oil shall be made by thoroughly grinding 
the specified pigment in pure raw or refined linseed oil. 
(c) Paste in Japan.—The paste in japan shall be made by thoroughly 
grinding the pigment in high-grade grinding japan. 


Il. PROPERTIES AND TESTS. 
3. (a) The color and tone shall be equal to, and the tinting strength not 
less than, that of a sample mutually agreed on by buyer and seller. 
(b) Dry Pigment.—The dry pigment shall meet the following requirements : 


Coarse particles retained on a standard No. 325 screen, maxi- 


mum, per cent ..55.. TPP 2.0 
Ash, maximum, per cent of pigment dried at 105° Gia 3 eee 88.0 
Ash insoluble in acids, maximum, per cent........-+.+++++ee-s Pere 
Benzol extract (which must be colorless), maximum, per cent.. 0.5 
Tone when diluted with zine oxide..........+-+++++- Clear-blue-gray 


(c) Paste in Oil.—The paste as received shall not be caked in the con- 
tainer and shall break up readily in oil to form a smooth paint of brushing — 
consistency. It shall mix readily in all proportions without curdling, with 
linseed oil, turpentine, or volatile mineral spirits, or any combination of these — 
substances. The paste shall meet the following requirements : 


Analysis of Black Pigments 759 


MAXIMUM MINIMUM 
EI EMCO Ge og eda cede vec. o. ee. eee 45 


Coarse particles and skins (total residue retained on a 
standard No. 325 screen, based on pigment), per 
Ss oo Ss bare PERM lek. 2.5 


(d) Paste in Japan.—The paste as received Shall not be caked in the con- 
tainer and shall break up readily in turpentine to form a smooth paint of 
brushing consistency that will dry within one hour to a hard, flat coat. It 
shall meet the following requirements : 


MAXIMUM MINIMUM 
(Se ENE BG So ee " 45 
Beecren japan). per cent... 0... bee e ee oo ek 55 ar 


OE oe Gace ne SSa a ha Pea 
Non-volatile matter in the vehicle, per cent of the 
ee ok koa Sy ooo cebcc ek: Sees 40 


4. One sample shall be taken at random from each lot of 1000 packages or 
less. If the packages are of such size that 1000 packages amount to more 
than a carload, one sample shall be taken at random from each carload. 


CHAPTER XLIV 


ANALYSIS OF IRON OXIDE PIGMENTS 
(Yellow, Orange, Red and Blue) 


The material originally published in previous editions of 4 


this volume has been utilized in the drafting of A. S. T. M. 
Specifications which are presented below. In addition to the 
methods recommended for determination of the iron content, 
reference might also be made to the use of a titanous chloride 
solution for reduction purposes,* or to the use of the Jones’ 


Reductor.t 


A.S.T.M. STANDARD METHODS OF ROUTINE ANALYSIS OF 
YELLOW, ORANGE, RED, AND BROWN PIGMENTS 
CONTAINING IRON AND MANGANESE 


GENERAL METHODS. 


SPECIFIC GRAVITY. 
1. True specific gravity shall be determined in accordance with the 
Standard Method of Test for Specific Gravity of Pigments (Serial Designation : 
D 153) of the American Society for Testing Materials. 


TINTING STRENGHT.# 

2 The colors should always be compared with a carefully selected standard. 
Weigh out accurately from 0.02 to 0.05 g. of color, place on a large glass 
plate, add 12 drops of bleached linseed oil,§ and rub up with a flat-bottom 
glass pestle or muller; then add 1 g. of pure ZnO, and grind with a circular 
motion 50 times; gather up with a sharp-edge spatula and grind out twice 
more in like manner, giving the pestle a uniform pressure. Next weigh out 
a similar amount of the standard, and treat in exactly the same manner as 
described above. Transfer portions of each paste to a microscope slide, quite 
close together, and then draw a palette knife across both samples so as to make 
them meet in a line (differences in tint are then easily seen). Compare the 
tints as shown on both sides of the glass. The amount of pigment used will 


vary with the tinting strength, but generally it suffices to take about 0.02 g. of © : 


the reds and about 0.05 g. of the ochers. 


* New Reduction Methods in Volumetric Analysis (1925). Cf. also Fox and @ 


Bowles—Analysis of Pigments, Paints and Varnishes, p. 50 (1927). 


+Scott, Volume I. 
tHolley, “Analysis of Paint an Varnish Products,” 1912, p. 126. 


§The use of “oxidized” oil should be avoided (oil that hsa become “fatty” $i 


by standing around in a can or bottle). Poppy-oil could be used but it is 


quite as necessary to have it reasonably fresh as when linseed oil is used. £ 


In either case “stringy” pastes are not reliable. 


q ki ae 
*? wae 
Bde eeu PL ey 


Iron Oxides: Yellow, Orange, Red,and Blue’ 761 


If it is desired to express quantitatively the tinting strength of the pigment, 
consider the standard pigment as having a tinting strength of 100, and then 
vary the amount of the standard pigment until the tints are matched. 

For example, let the amount of standard pigment for 100 strength test be 
0.02 g. (=A). Vary this amount in units of 5 per cent, thus 0.019 or 0.021. 
Let the amount taken to match a given strength — B, then 


B 
0 
Tee 


equals the tinting strength of the sample to be tested. 
If the tone varies it may be difficult to make this measurement. | 


ADDED COLORING MATTER. 

3. Test the pigment successively with hot water, 95-per-cent ethyl alcohol, 
alcoholic NaOH or KOH and acetic acid. Chloroform, NaOH, H,.SO,, HCl- 
Stannous chloride, and other reagents may be tried." The presence of an 
stannous chloride, an other reagents may be trie.* The presence of an 
if desired.f 

METHODS OF ANALYSIS OF INDIAN REDS, RED OXIDES 


(PRINCE’S METALLIC, TUSCAN RED.) 
LOSS AT 100° C. 


4. Heat 2 g. in a steam-jacketed oven at atmospheric pressure for three 
hours, or to constant weight. 


LOSS ON IGNITION. 

5. Ignite a portion in a covered porcelain crucible to constant weight. . 
This may include combined water, CO,, organic matter, and some SO, if much 
CaSO, is present. CO, may be determined on a separate portion of the sample 
if desired.’ 

FREE ACID OR ALKALI. 

6. Boil 10 g. of sample with 100 cc. of water; filter and wash. Test filtrate 
with litmus paper; if acid, titrate with standard alkali and methyl orange 
and calculate to the equivalent of H,SO, If alkaline, titrate with acid and 
calculate to the equivalent of Na,O. Test filtrate for alkali salts and alkaline 
earths. 


ADDED COLORING MATTER. 
7. Tests as under “General Methods.” 


INSOLUBLE, IRON OXIDE, ETC. 

8. Digest 2.5 g. of the sample (previously roasted at a low temperature if 
much organic matter is present; if very low in carbonaceous matter a little 
KC1O:; or NaClO, may be used in effecting solution) with 25 ec. of HCl (adding 
a little HNO, or chlorate, if not already added), wash off cover, and evaporate 
to dryness. Take up with HCl and water, filter, wash with dilute HCl and 


*Mor details consult Berr. “Tests for Coal-Tar Colors in Aniline Lakes.” 
(English translation by C. Mayer) ; Schultz and Julius, “A Systematic Survey 
of the Organic Coloring Matters;” Hall, “The Chemistry of Paints and Paint 
Vehicles;:” and Mulliken, “Identification of Pure Organic Compounds,” Com- 
mercial Dyestuffs, Vol. III. 

7It is inadvisable to use platinum unless it is known that attacking sub- 
stances are absent. 


762 Iron Oxides: Yellow, Orange, Red, and Blue 


cold water. Make the filtrate up to 500 cc., mix, and examine as below.* 
Ignite the residue and weigh as “insoluble matter’; if this contains BaSO, 
it may be determined by fusing with six times its weight of Na,CO,, cooling, — 
digesting with hot water, filtering, and washing the residue with hot water — 
‘until free of sulfate. * 


Remove filtrate and place beaker used for the digestion underneath the — 
funnel, pierce the filter with the glass rod, and wash the residue with a little ‘ 
water into the beaker; then pour hot dilute HCl (1:1) over paper, and finally — 
wash with hot water. If necessary add more HCl to the beaker to dissolve — 
the BaCO,; heat to boiling, add dilute H,SO, in slight excess, let stand about ~ 
one hour on steam bath; filter, wash, dry, ignite, and weigh BaSO, (This — 
subtracted from total insoluble will give “insoluble silicious matter,” if it is i 
desired to so report.) If it is desirable to analyze the insoluble silicious — 
matter, this can be done by the usual methods for silicate analysis, but the 
results should be reported as a separate analysis. 


For the determination of iron place 100 cc. of the first filtrate in a flask, © 
add about 3 g. of granulated zinc, put a funnel into the neck of the flask, heat — 
when the action slackens; if basic salts separate out add a few drops of HCl. — 
When the reduction is complete, add 30 ce. of H,SO, (1:2), and as soon as 
the residual zinc is dissolved, wash down the funnel inside and out and the © 
neck of the flask with a fine jet of water, filling the flask (1000 cc.) about 
two-thirds full, cool in water, add 10 cc. of “titrating solution” (made by dis- 
solving 160 g. of manganese sulfate in water, diluting to 1750 cc., adding 330 — 
ce. of H,PO,, sp. gr. 1.72, and 320 cc. of concentrated H,SO,), and titrate with © 
KMnO, (5.659 g. per liter) that has been standardized against Bureau of © 
Standards sodium oxalate. Run a blank on the zinc, correct for same and — 
calculate total iron as Fe.O,. Instead of adding the zine to the solution, — 
the reduction may be effected in a zine reductor.¢ ; 

The Fe,O, may also be determined by the K.Cr,0, method.§ 


LIME. 

9. Dilute an aliquot of 100 cc. of the original solution to about 200 ce., add — 
10 ce. of HCl, make alkaline with NH4,OH, add 2 or 8 cc. of bromine water. 
and boil till excess of NH» is expelled. Let settle, wash by decantation, — 
redissolve in HCl, and reprecipitate with NH,OH and bromine water, (Pre- — 
cipitate — Fe,O,.Al,0,.T10,.P,0..MnO,.) This precipitate may be ignited ® 
and weighed if desired. § 

To the combined filtrates add a few drops of NH4,OH, heat to boiling, and © 
add an excess of saturated ammonium-oxalate solution; continue the boiling 
until the precipitate becomes granular, let stand about 30 minutes, filter, and — 
wash with hot water till free of ammonium oxalate;|| place beaker in which — 
precipitation was made under the funnel, pierce apex of filter with stirring — 


*For more exact work this filtrate should be evaporated to dryness and ; 
SiO, removed. 


*If the insoluble contains appreciable amounts of Fe it will be necessary 
to fuse it with Na,CO, or K,S,O, to determine total Fe in samples. 
tLord and Demorest, “Metallurgical Analysis.” 19138, pp. 28-29. 
§/bid., pp. 21-26. ; 
é 
|For more exact work this precipitate should be dissolved in HC] and the 
calcium oxalate reprecipitated as above. 


a I 


Iron Oxides: Yellow, Orange, Red,and Blue’ 763 


rod and wash precipitate into beaker with hot water, pour warm dilute 
H.SO, (1:4) through paper and wash a few times; add about 30 ce. of 
H,SO,4 (1:4), dilute to about 250 cc., heat to 90° C. and titrate at once with 
standard KMnO, solution (solution should not be below 60° C. when end-point 
is reached). Calculate to CaO. (The Fe value of KMnO,X0.502—CaO.) The 
calcium-oxalate precipitate may be ignited to constant weight as CaO. If 
desired, magnesia may be determined as Mg P.O, in the usual manner in 
the filtrate from the calcium oxalate.* 


SOLUBLE SULFATES. 

10. Treat 1 g.¢ of the pigment (roasted gently if much organic matter is 
present) with 30 ce. of HCl, boil 10 minutes, add about 50 cc. of water, boil, 
filter, and wash with hot water. Heat the solution to boiling, add NH,OH, 
filter and wash a few times with hot water; dissolve precipitate in hot dilute 
HCl and reprecipitate with NH,OH, wash well with hot water. Render united 
filtrates just distinctly acid with HCl, boil, add by drops with stirring excess 
of 10-per-cent BaCl, solution, boil about 10 minutes, filter on a Gooch crucible, 
wash with hot water, ignite and weigh as BaSOy. Calculate to SO3 or CaSQx,. 


TOTAL SULFUR OTHER THAN THAT PRESENT AS BaSQy,. 


11. Treat 5 g. of the sample in a covered porcelain dish with 50 ce. of aqua 
regia ( 1 HNO,:9 HCl) and evaporate to dryness on steam bath. Add 20 ce. 
of concentrated HCl and about 250 cc. of water, make double NH4,0H precipi- 
tation; determine BaSO, as given under “Soluble Sulfates.” 


METHODS OF ANALYSIS OF OCHERS 


12. Loss at 100° C., loss on ignition, insoluble matter, total or soluble iron, 
alumina, lime and sulfur may be determined as outlined under the “Methods 
for Analysis of Indian Reds, etc.,’’ using 1 g. or an aliquot corresponding to 
this weight. 

TINTING STRENGTH. 


13. Test as under ‘General Methods.” Tests should be made for solubility 
in water, and reaction to litmus paper. 


LEAD CHROMATE. 


14. If present, the lead is removed in the above scheme by nearly neutral- 
izing the filtrate from the insoluble matter with NH,OH, cooling, and passing 
in H.S, to precipitate PbS. Filter, wash with water containing H2S, dissolve 
PbS in hot dilute HNOs, add 10 cc. of concentrated H2SO4, evaporate till SOg 
is evolved, cooi, dilute to 200 cc., let stand a few hours, filter on a Gooch 
crucible, wash with 1-per-cent H»SO,4, ignite, and weigh PbSO,4. Calculate to 
PbO or Pb. Heat the filtrate from the PbS to expel HoS, oxidize with a little 
HNOs, and make up to volume if working on more than 1 g. 


*Tf desired, a direct determination of Al O, may be made on an aliquot of 
the solution or on the HCl solution of the NH:OH precipitate by Peters’ phos- 
phate method (this will include titanic acid) as described by Blair. “The 
Chemical Analysis of Iron,” and Philips, ‘‘“Methods of Iron Analysis Used in 
the Pittsburgh District.” 


+If low in soluble sulfates use a larger portion of sample. 


764 Iron Oxides: Yellow, Orange, Red, and Blue 


The iron is best determined in an aliquot by the K>Cr,07 method. Another” 
aliquot is treated with NH,OH, the precipitate containing Alj.O3. Fe 03.Cr203. 
P,0;5.TiOg. Lime and MgO may be determined in filtrate. . 

The NH,OH precipitate is dissolved in hot dilute HCl, washing paper with ; 
hot water, cooled, oxidized with Na,O, boiled to expel H,O ,, cooled, cover et 
glass washed off, diluted to about 150 cc., and acidified with H,SO4. Add a i 
measured excess of ferrous ammonium-sulfate solution— (NH4)2Fe(SO4)9. — 
6H,O, 12.4 g.; concentrated H,SO,, 50 ce.; and water to make 1 liter, and b 
titrate back with standard KyCr,O, solution, using K3;Fe(CN)¢ solution as an ~ 
outside indicator. The (NH4) .Fe(SO4)2.6H.O solution is titrated with the — 
K,Cr.07 solution to determine its value in terms of the latter. The Fe value ) 
of the K,Cr,0, solutionX0.597=CrO3. : 

Or, moisten 1 g. of the pigment with water, add 5 ce. of concentrated HCl, 
boil a few minutes, cool, add Na ,O, in excess, boil to expel HO02, cool, wash ~ 
off cover glass, dilute, acidify with H S04, and titrate CrOg as above. 


VENETIAN RED. F 

15. Analyze as given ‘under “Methods for Analysis of Indian Reds, etc.” 
Insoluble matter may be treated with HF and H»S0O,4 to determine SiO, by ~ 
loss if desired. ‘ 


METHODS OF ANALYSIS OF SIENNAS AND UMBERS., 
16. After gently roasting to destroy organic matter, test as given under 
“Methods for Analysis of Indian Reds, etc,” 


MANGANESE. : 
17. Manganese is determined by the bismuthate method.* Ignite gently ~ 
(to destroy organic matter) 1 g. of the sample in a platinum dish, cool, add 
10 ce. of water 4 ce. of concentrated H,SO, and about 20 ce. of HF (if neces- 3 
sary, add a little sulfurous acid). Evaporate until the Hj,SO, fumes freely, — 
cool and dissolve in 25 cc. of HNOg (1 part concentrated HNO, to 3 parts © 
water). If no appreciable residue remains, transfer to a 100-cc. volumetric 
flask, using 25 ce. of HNOg (1:3) to rinse the dish, dilute to the mark with © 
water, mix thoroughly. If there is an appreciable residue, filter on a small ; 
filter, wash with water, ignite residue in a platinum crucible, and fuse with © 
a little sodium or potassium pyrosulfate. Dissolve in water, with the addition ~ 
of a little HNOs, add to the main filtrate, evaporate nearly to dryness, take up — 
in HNO, (1:3) and transfer to the flask as before. Pipette an aliquot of 10 ; 
ce. into a 200-cc. Erlenmeyer flask, add 30 ce. of water and 10 ce. of concentrated — 
HNO,, sp. gr. 14; add about 0.5 g. of sodium bismuthate, heat for a few 
minutes, or until the pink color has disappeared with or without the precipita- 
tion of MnO»,. Add a few small crystals of sodium or potassium nitrite to 
dissolve the MnO, and boil the solution several minutes to expel nitrous 
fumes (a little NasCOz, will aid this). Add water to bring the volume up to 
50 ec. and cool to about 15° C.; add about 0.5 g. of bismuthate and shake the — 
flask well. Add 50 ce. of water containing 30 ce. of concentrated HNO: to the 
liter, filter by suction through an asbestos felt into a 300-cc. Erlenmeyer flask — 
and wash with 50 to 100 cc. of the same acid. Run in a measured volume of — 
standard ferrous ammonium-sulfate solution and titrate to a faint pink color _ 


*Blair, “The Chemical Analysis of Iron.” 


Iron Oxides: Yellow, Orange, Red,and Blue 765 


with standard KMnO, solution. The number of cubic centimeters of the KMnO, 
solution obtained, subtracted from the number corresponding to the volume 
of ferrous solution used, will give the volume of KMnO, equivalent to the 
manganese in the sample, which, multiplied by the value of the KMnO, in 
Mn, gives the weight of manganese in the portion of sample used. 

Standard KMnO, Solution.—The solution of KMnO, is composed of 1 g. 
dissolved in a liter of water. The Fe value of this solution « 0.197 = Mn 
This solution may be standardized against Bureau of Standards sodium 
oxalate (using about 0.05 to 0.1 g.).* Weight of Na.C.O, * 0.197)—= Mn 
Twelve grams of (NH4)oFe(SO,4)5.6H».O, 25 ce. of concentrated H2.SO,4, and 
25 ce. of HgPO4, sp. gr. about 1.7, are made up to 1 liter with water. The 
value of this solution should be determined against the KMnQO, each day as 
follows: 

Measure into a 200-cc. Erlenmeyer flask 50 cc. of HNO; (1:3), cool, add a 
little bismuthate, dilute with 50 cc. of 3-per-cent HNOs, filter by suction 
through an asbestos felt into a 300-cc. Erlenmeyer flask, and wash with 50 cc. 
of 3-per-cent HNOs. Run in 25 cc. of the ferrous solution and titrate with 
KMnOy, solution. Instead of titrating the permanganie acid formed by the 
bismuthate with the ferrous solution and then titrating back with KMn0O,, 
a direct titration with standard sodium arsenite solution may be made.t 


A.'S.T.M. TENTATIVE SPECIFICATIONS FOR MINERAL IRON OXIDE. 
1. These specifications cover iron oxide and iron hydroxide pigments of 
mineral origin and of red and brown colors. 


I. MANUFACTURE. 

2. (a) Dry Pigment.—The pigment shall be very finely ground iron oxide 
or iron hydroxide or a mixture thereof. Siliceous minerals may be present 
and, if necessary, sufficient carbon pigment may be added to produce the 
desired color. 

(b) Paste——The paste shall be made by thoroughly grinding the specified 
pigment with pure raw or refined linseed oil. 


II. PROPERTIES AND TESTS. 
3. (a) The mass color and character of the tint formed by mixture with a 
_white pigment shall be the same as, and the strength not less than, that of a 
sample mutually agreed upon by buyer and seller. 
(b) Dry Pigment.—The pigment shall conform to the following require- 
ments: 
MAXIMUM MINIMUM 


MCPOMICG POP CONG. .cacice ccc secs etuwecesevepas its 30.0 
Material other than ferric oxide, insoluble siliceous 

matter and loss on ignition, per cent............. 10.0 
Coarse particles retained on a Standard No. 325 

MRP EPEC ONIN re p59. nice cas ab ote pe ite ha wees a's, « bese 3.0 


Organie coloring matters shall be absent. 


The color and color strength, when specified, and the drying time with a 
vehicle which has been mutually agreed on, shall be equal to those of an 
agreed sample. 


*W. Blum, “Original Communications,” Eighth International Congress of 
Applied Chemistry, Vol. I, pp. 61-85. 
*Lord and Demorest, “Metallurgical Analysis,” 1913, p. 82. 


766 Iron Oxides: Yellow, Orange, Red, and Blue 


(c) Paste-——The paste as received and three months thereafter shall not 


be caked in the container and shall break up readily in linseed oil to an 
a smooth paint of brushing consistency. It shall mix readily with linseed oil, | 


turpentine or volatile mineral spirits, or any combina of these, without 
curdling. 
The paste shall conform to the following requirements: 
MAXIMUM MINIMUM 


Pigment, per’ Cent... ...se<s's5 v0 9 seers mee ear 72.0 68.0 4 
Linseed oil, per Cent... 26. o< 206 ewes yo eee eee 32.0 28.0 
Moisture and other volatile matter, per cent......... 0.7 Ease 


Coarse particles and skins (total residue retained on 
a Standard No. 325 sereen, based on pigment), 
POP CONG. . ev sewn ae cee cele eee om oe beeen 3.5 cise 


4. One sample shall be taken at random from each lot of 1000 packages | 


or less. If the packages are of such size that 1000 packages amount to more 


than a carload, one sample shall be taken at random from each carload. 


A.S.T.M. STANDARD SPECIFICATIONS FOR OCHER. 


1. These specifications cover ferrous earthy pigments, included under the— 
general term “Ocher” and purchased either as dry pigment or ground in oil | 


or in japan to form a paste. 


MANUFACTURE. 
2. (a) Dry Pigment.—The pigment shall be a hydrated oxide of iron, 
permeating a siliceous base, and shall be free from added impurities and added 
coloring matter. 


ere 


(b) Pastes in Oil—The aste shall be made by thoroughly grinding thal 


specified pigment in pure raw or refined linseed oil. 
(c) Pastes in Japan.—The paste shall be made by thoroughly grinding the 
specified pigment in high-grade grinding japan. 


PROPERTIES AND TESTS. 


3. (a) The mass color and character of the tint formed by mixture with a 


white pigment shall be the same as, and the strength shall not be less than, 


that of a sample mutually agreed upon by the buyer and seller. 


ments: 
MAXIMUM MINIMUM 
Coarse particles retained on a No. 325 screen, per cent 1.0 


Iron oxide (Fe O03), per cent. ..4 5.5.00 se ee pan ieee syste 17 
Lime CaO), per cent. vec. s J. « sicuwie sie ene PR 5 45 
Lead, chromate, per CONC. 2.25. 02s dss «anit oe pee None 
Orgahie colors, pet C@Dt...: 04s 0's «ss 0 so Gis eee None 


(c) Paste-——The paste as received shall not be caked in the container and | 


shall break up readily in oil to form a smooth paint of brushing consistency. 


(b) Dry Pigment.—The pigment shall conform to the following requilaay 


It shall mix readily in all proportions, without curdling, with linseed oil, 
turpentine or volatile mineral spirits, or any mixture of these substances. 


The paste shall conform to the following requirements : 
MAXIMUM MINIMUM 


Pigment, per Cent. ..o05 005.5 0s le 0 aca) cee 73 69 
Linseed ofl, per Cent... .s4 06. «ac 5 0 slew sen 31 27 
Moisture and volatile matter, per cent............... 0.5 se 


Coarse particles and skins (total residue retained on a 
Standard No. 325 screen, based on pigment), per 
COTE. 05.00 va: 0 nee 80 evo wane bdo wets om Fea, eee 


Gold Bronze, Aluminum Bronze 767 


(d) Paste in Japan.—The paste as received shall not be caked in the con- 
fainer and shall break up readily in turpentine to form a smooth paint of 
brushing consistency that will dry within one hour to a hard, flat coat that 
can be varnished within five hours of the time of application, without streaking 
or bleeding. The paste shall conform to the following requirements: 


MAXIMUM MINIMUM 


ITO T HCCI ON 6. GS. oo ls cc ceo ca cc ee ce acces Ts 69 
Peer C aT) ADET CONG. 6 ek cede ccc coe ce can weve 31 at 


Coarse particles and skins (total residue retained on a 

Standard No, 325 screen, based on pigment), per 

ee se eh os oe vs beck 6 esc acd bcleloee bles 1.5 Ne 
Non-volatile matter in vehicle, per cent of the vehicle .... 40 


4. One sample shall be taken at random from each lot of 1000 packages 
or fraction thereof. If the packages are of such size that 1000 packages 
amount to more than a carload, one sample shall be taken at random from 
each carload. 


A. 8. T. M. TENTATIVE SPECIFICATIONS FOR GOLD 
BRONZE POWDER 
1, These specifications cover the materials commonly known as gold bronze, 
pale gold bronze, and rich gold bronze powders. 


PROPERTIES AND TESTS 

2. (a) The gold bronze powder shall be suitable for making gold bronze 
paint. It shall match in shade and fineness a sample mutually agreed upon 
by the buyer and seller. 

()) It shall be made from new ingot metals and the finished powder shall 
consist essentially of copper and zine. It shall consist of fine polished flakes 
with not to exceed 3 per cent of fatty or oily matter (polishing lubricant) to 
give good “leafing” properties. 

(c) It shall “leaf” readily with spar varnish and ordinary bronzing liquids, 
and when mixed in the proportion of 314 to 4 lbs. to a gallon, shall give a free 
flowing, smooth, continuous coating. 

(d@) A residue of not more than 0.1 per cent shall be retained on a No. 
100 sieve. 

8. One sample shall be taken at random from each lot of 1000 packages 
or fraction thereof for purpose of test. 


A. S. T. M. TENTATIVE SPECIFICATIONS FOR ALUMINUM 
POWDER FOR PAINTS 


1. These specifications cover the material produced by a stamping process 
and commonly known as “aluminum bronze powder.” The product produced 
by a spraying operation, which consists of more or less nearly spherical par- 
ticles, and is sometimes known in the trade as “aluminum powder,” is not 
covered by these specifications. 


PROPERTIES AND TESTS 

2. (a) The aluminum powder shall be suitable for making aluminum paint. 

It shall match in luster and fineness a sample mutually agreed upon by the 
buyer and seller. 


‘ND 


b> 


768 A. 8S. T.M. Standard Definitions 
eee 

(bo) It shall contain no filler or adulterant, such as mica, and shall be 
commercially pure aluminum in the form of fine, polished flakes with not to 
exceed 3 per cent of fatty or oily matter (polishing lubricant). 

(c) It shall have good “leafing’” properties (by ‘Jeafing” is understood 
the property of forming an apparently continuous brilliant film over the entire 
free surface of a mixture of the powder in spar varnish within one minute 
after cessation of stirring the mixture). 

(d) A residue of not more than 0.2 per cent shall be retained on a No. 100 
sieve when the powder is washed through with alcohol. It shall “leaf” readily 
with spar ‘varnish,* and when mixed with such varnish in the proportion 
of 2 lbs. to the gallon shall give a free flowing, smooth, continuous coating. 

3. One sample shall be taken at random from each lot of 1000 packages or 
fraction thereof for purpose of test. 

EEE EE EEEEEEEEED 


A. 8. T. M. STANDARD DEFINITIONS OF TERMS USED IN 
PAINT SPECIFICATIONS 


Standard.—Materials, methods, qualities, properties, etc., set forth by speci- 
fication as a basis for the measurement of requirements. 
Equal To.—The use of this term should be avoided if possible. 

The avoidance of this term is recommended wherever possible because 
the specifications themselves should state ‘the qualities, ete. desired. In 
specifications having the sanction of the American Society for Testing 
Materials, it is to be assumed that this feature will be developed to its fullest 
extent. 

Pure.—Free from admixture of any foreign substance. 
Commercially Pure—The use of this term should be avoided if possible. 

The avoidance of this term is recommended wherever possible because it 
involves the acceptance of standards likely to cause dispute, whereas speci- 
fications having the sanction of the American Society for Testing Materials 
should involve the establishment of their own standards. 


Adulteration.—The partial substitution of one substance for another without 
acknowledgement. 

The addition of the words “without acknowledgment” makes this defini- 
tion clear. Substitution with acknowledgment involves no improper motive. 
If it is done without acknowledgment an improper motive may be assumed. 
Adulterant.—A substance substituted partially for another without acknowl- 

edgment. 
Opacity—The degree of obstruction to the transmission of visible light. 

In this sense “opacity” is a relative term, it being considered that given 
a film sufliciently thin, in paint technology at least, there is no absolutely 
opaque substance. 

Covering Power.—The use of this term should be avoided if possible. 

This term has been used so loosely that it might mean hiding power, 
spreading power, or the simple property of producing a coat. 

Hiding Power.—The power of a paint or paint material as used to obscure 
a surface painted with it. 

In this definition the word “obscure” means to render invisible or to 

cover up a surface so that it cannot be seen. 


* Federal Specifications Board Specification No. 18, Varnish, Spar, Water- 
Resisting. oy 


ay, 
oy 


A.S. T. M. Standard Definitions 769 
a ee ba al ae rear: Seale ate nn Ret bd 


Spreading Rate.—The rate at which a paint or paint material, as used, is 
brushed out to a continuous uniform film expressed in terms of the area 
to which a unit volume, as used, is applied. 


This term must not be confused with the much-abused term “spreading 
power.” The use of the term “spreading rate” is illustrated in the following 
sentence: “The paint when spread on a planished iron surface at the rate 
of 600 sq. ft. to the gallon will not sag or run when placed in a vertical 
position at 70° F.” 

Fineness.—The extent of sub-division of a substance as indicated under 
definite prescribed conditions. 


Orystallin— Having a definite structure referrable to one of the erystallo- 
graphic systems. 


According to definition a material is not crystallin if it has not a crys- 
tallin form irrespective of the optical and other properties it may possess. 


Amorphous.—Without regular or definite form. 


This definition as given here has a broader meaning than it possesses 
when it is used in mineralogical writings. Protozoa, if of definite form, are 
not amorphous and may not be crystallin. 


Paint——A mixture of pigment with vehicle, intended to be spread in thin 
coats for decoration. or protection, or both. 


According to this definition a mixture of pigment and varnish is a paint, 
and on the other hand a solution of stains in oil or varnish, no pigment being 
present, is not a paint. 


Size—In the painting art, a liquid coating material, intended to close the 
pores, used to prepare a surface for further treatment. 
It is not regarded as a finishing material 


Varnish.—A liquid coating material, containing no pigment, which flows out 
to a smooth coat when applied and dries to a smooth, glossy, relatively 
hard, permanent solid when exposed in a thin film to the air. 


Some materials possessing the other characteristics dry without the usual 
gloss and are termed “flat varnish.” 


Enamel.—A special kind of paint which flows out to a smooth coat when 
applied and dries to a smooth, glossy, relatively hard, permanent solid 
when exposed in a thin film to the air. An enamel always contains pig- 
ment and has considerable hiding power and color. Some enamels dry 
to a flat or eggshell finish instead of a gloss finish. 


Filler—A special kind of paint used for filling pores or other small breaks 
in the continuity of a surface to render it smooth preparatory to further 
treatment. When applied and exposed to the air, a filler should dry to a 
relatively hard, permanent solid capable of properly supporting subse- 
quent coats. 


Pigment.—The fine solid particles used in the preparation of paint, and sub- 
stantially insoluble in the vehicle. 
Asphaltic materials are not pigments except when they contain substances 

substantially insoluble in the vehicle in which they are used. 

Toner.—An organic pigment which does not contain inorganic pigment or 
inorganic carrying base. 


_ Lake—A special type of pigment consisting essentially of an organic soluble 


coloring matter combined more or less definitely with an inorganic base 


770 A. S. T. M. Standard Definitions : 


or carrier. It is characterized generally by a bright color and a more é 
or less pronounced translucency when made into an oil paint. 


Under this term are included two (and perhaps three) types of pigment: 
(a) the older original type composed of hydrate of alumina dyed with a 
solution of the natural organic color, (b) the more modern and far more 
extensive type made by precipitating from solution various coal-tar colors — 
by means of a metallic salt, tannin, or other suitable reagent, upon a base ~ 
or carrier either previously prepared or coincidently formed, and (¢) a num- — 
ber combining both types in varying degree, might be regarded as a third class. 
Vehicle—The liquid portion of a paint. 


Here anything that is dissolved in the liquid portion of a paint is a part 
of the vehicle. 
Volatile Thinner.—All that liquid portion of a paint, water excepted, which — 


is volatile in a current of steam at atmospheric pressure. ; 
Non-Volatile Vehicle-—The liquid portion of a paint excepting its volatile 
thinner and water. 
Drying Oil.—An oil which possesses to a marked degree the property of@ 
readily taking up oxygen from the air and changing to a relatively hard, 
tough, elastic substance when exposed in a thin film to the air. 
Semi-Drying Oil.—An oil which possesses the characteristics of a drying oil 
but to a less degree. 


There is no definite line of demarcation between drying and semi-dryingg & 
oils. 
Non-Drying Oil.—An oil which does not of itself possess to a perceptiblaam 


degree the power to take up oxygen from the air and lose its liquid — 
characteristics. 3 
Tinting Strength—The power of coloring a given quantity of paint or pigment — ¥ 
selected as a medium standard for estimating such power. : 
Color—A generic term referring inclusively to all of the colors of the spec-_ : 
trum, white and black, and all tints, shades and hues which may be 
produced by their admixture. 4 


Color involves a definite effect produced by the action of light upon the | 
retina of the eye dependent upon the optical composition of the light. This 
term is also used in reference to material substances such as pigments, stains, 
dyes, ete., but in specifications it should be recognized that color is primarily 
a physiological sensation, 


By ee 


Tint.—A color produced by the admixture of a coloring material, not white, 
with a white pigment or paint, the white predominating. £ 
Shade-—A term descriptive of that difference between colors which results K 
from a difference in luminosity only, the other color constants being 
essentially equal. A darker shade of a color is one that has a lowe 
luminosity. | 
Primarily the term “shade” is akin to shadow designating darkness or 
reduced illumination, and therefore when strictly used should eXpress only 
such change as depends on reduced luminosity ; it has been defined by several - 
authorities as the mixture of black with a color, thus establishing its opposite 
character to “tint,” but by extension of its relative sense it has been fre- 
quently and widely used to include lighter shades by use of the adjective 
“lighter” or “paler.” Although such expressions apparently involve a contra-— 
diction, it is clear that while we may have a shade of color or darker color 


of the same sort, it is easy to conceive of another shade not quite so dark and 
therefore lighter. 


Hue.—The predominating spectral color in a color mixture. 
Tone.—The color which principally modifies a hue or a white or a black. 


aD 


A.S. T. M. Standard Definitions id 
ne SS a 


Drying.—The solidification of a film. 


Drier.—A material containing metallic compounds added to paints and paint- 
ing materials for the purpose of accelerating drying. 

Specific Gravity——The ratio of the weight of a unit volume of a substance to 
the weight of an equal volume of water at defined temperatures. 


Density.—The use of this term should be avoided if possible. 


Density is a scientific term meaning the mass of a unit volume. Its 
numerical expression will vary with the units selected, and there is no ocea- 


. 


sion for using it when the term “specific gravity” is defined. Confusion may 

be avoided by not using the word “density” in specifications, 

Gallon.—The measured gallon is 231 cu. in. Where a measured gallon is 
called for, the temperature at which it is to be measured should be 
specified. Where a gallon of definite weight is called for, the weight 
should be specified or obtained from the specific gravity of the material 
at a definite temperature. 

This is the standard United States gallon. 


Water.—Dissolved water or water not definitely or chemically combined. 


Dry.—In paint materials: containing no uncombined water. In paint films: 
completely solidified. 


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Abrasion resistance............. 
Accelerated method of testing 

painted cement surfaces...... 
Accelerated tank for cement test- 

ing 
Accelerated testing cabinets .... 
Accelerated tests on galvanized 

pipe 
Accelerated tests on- metals.... 
Acidity of oil affecting lithopone 
Acid number of varnish........ 
Acid value of varnishes........ 
Air bubble viscometer.......... 
Merlin tension............... 


eeeeoeree ese ee eeer eee eeee ee 0 @ 


eoeceee eee eeees ee eee eee eee eo 


Airplane dopes, Durability of .399, 


Airplane dopes, Durability tests 
Airplane fabric, Durability of. es 
Alkali increase test for tung oil 

varnishes 


Aluminum alloys, Paint tests 
pS el Are eel ie a 
Aluminum powder, A.S.T.M. ten- 
tative specifications for....... 
Aluminum primers for wood.... 
Aluminum stearate gel.......... 


Aluminum stearate, Jelly test.... 
Aluminum stearate, Specifications 
for 
Aluminum stearate, Testing of. 
Analysis and _ specifications for 
ME PCOOUINE Coe ics et eee es 
Analysis of lacquer, 
for 
Analysis of mixed driers...... 
mapivsis Of paint olls.......... 
Beer yeas OF PAINS. . 06.06. .e e ees 
Analysis of pyroxylin coatings.. 
Merriseot SHeMAC...3......5.- 
Meiveis sol Vvarnish............ 
Analysis of varnish resins...... 
PeerOUMNNe PAINtS.......0....6. 
Apparatus for testing tung oil.. 


Apparent density of pigments.... 
meeem nbrasion test............ 
Ash in varnish...... Seb oe Ree 
A. S. T. M. cooperative work on 
Mexapromide test............. 
A. 8. T. M. method for reporting 
0 | 
A. S. T. M. method of examina- 
tion of lacquer pigments...... 
A. 8. T. M. proposed methods for 
testing lacquer enamels...... 
A. S. T. M. recommended tenta- 


_ tive specification for soluble 
nitrocellulose 


447 


424 
bo4 


A. S. T. M. specifications for 
COATSEG PATHICles ois se Gees w cece 
A. S. T. M. standard method for 
BPOCIIC= STA VIE Mee Sons area a kw whens 
A. S. T. M. standard method for 
testing oleo-resinous varnishes 
A. S. T. M. standard method of 
test for flash point of volatile 
flammable» liquids... 232.94... 
A. S. T. M. standard methods for 
COSTING SGM Be eels ees eee 
A. S. T. M. tentative specifications 
Sampling and testing turpen- 
tine 
A. 8S. T. M. standard specification 
LOT? Orange -SHEHACY co 44s Wks 6. 
A. S. T. M. standard specification 
for perilla oil, raw or refined 
A. S. T. M. tentative method for 
determination of wax in shellac 
A. 8. T. M. tentative method of 
test for elasticity or toughness 
of varnishes by addition of lin- 
BCU SOL othe se Gost aie See 
A. 8. T. M. tentative method for 
testing insulating varnish..... 
A. S. T. M. tentative methods of 
sampling and testing’ lacquer 
solvents and diluents......... 
A. S. T. M. tentative methods of 
testing shellac varnish........ 
A. S. T. M. tentative specification 
for boiled linseed oil......... 
A. 8. T. M. tentative specification 
for petroleum spirits (mineral 


eoeeee ere eee eee ese eeeee eee 


SDLCILS hare ee ata ea ays 
A. 8. T. M. tentative specification 
for raw linseed oil............ 


A. 8. T. M. tentative specification 
LOVTRW CON SEOs soe ee alectale wie t's 
A. S. T. M. tentative specification 
for soya bean oil, raw or re- 
fined 


oe eee eee ee eee www eee ee ee 


592 


A. 8S. T. M. tentative specifications — 


for destructively distilled wood 
turpentine 
A. S. T. M. standard specifications 
for gum spirits of turpentine 
and steam distilled wood tur- 
pentine 
Atlantic City exposure tests.... 
Atlas accelerated testing cabinet 
Automobile black baking enamels, 
Testing 
Automobile black baking japans 
Average specific gravity data.... 


Cr 


oe eer eee eee eee eee ee ee wo ow 


eoeoerreree eee ee eee ee ee eee 


369 
322 


548 
537 
144 


774 


Index 


Bailey’s hexabromide test on oils 420 


Baking ‘japans; Black vawvs esa. 537 
Barton’s method for tinting 
SUYONSET i SS is eae ee eres hs 303 
Basic carbonate white lead..... 697 
3asic sulphate white lead...... 698 
Bawtree colorimeter............ 229 
Bending tests on lacquers...... 618 
Beta-elaeostearin, Accelerators 
FOR proaguchie <6 ss. Bei een ate 45 
Bituminous black baking japans 537 
Bituminous cements..........%> 537 
Bithmimous painte.es. fu. saeco 
Bituminous varnishes........... 536 
« Blaek. baking’ -Ja pans. -35t ose At 
Boiling point of lacquers........ 610 
Bolton’s method for tung oil test- 
tin? cal een Ges tia cis pee 434 
Bone DICK 6a Sha civ aty Wen a 758 
Break. test: ‘tn oleic. ae 407 
Brightness of pigments........ 19-24 
Brush-cleaning device........... 296 
Brushing tests on lacquers...... 619 
Bulking value of paints........ 146 


Bulking value of paint liquids... 150 
Bulking value of pigments.. .144, 145 


Cements, Bituminous..... By Dee 
Cement test, Super-accelerated.. 391 
Chemical examination of fossil 


YTESIDN - 5 Ula ae ne ees ee 492. 
Chevreul’s color chart.......... 224 
Chrome Oxide green............ 751 
Chreme<cyellew iia 205 tei oe 753 
Chromium pigments............ 736 


Chrysanthemists color system.... 2 
Clarity test, Toluol insolubility, 
TOF SPORID..GS os aoe 511 
Cleaning brushes... 652. vier. css sn ee 
Clemens hardness apparatus.... 60 
Coarse particles in paint pig- 


SYHOTIUS 2 ER. vidas whee emir ueie ae eae 151 
Coleman-Fellows method for oil 
contentvor. flaxseed 25.0.0. ees 570 
Color comparisons of resins.... 510 
Color” :Giscusston 7 o's. eae cee 250 
Color, Graphical representation 

0 iy BERS. Renee ae Soe 241, 246, 248, 249 
Color number of dry pigments, 

a! Wied Alle ip catia bodes ne aeraee 649, 652-654 
Color reference standards, Sec- 
OQUUATY: J ca5. be Cee ee enetee 2905 
Color of resin, Pfister method 
TOP? o aed atalevracag Pere Rice ee 406 
Color standards for varnishes.. 479 
OLOL.” BY RUCNIN ioscan, cate ee LT 


Color of white opaque pigments 300 


Colored building materials, Tem- 
perature! Of.4).4% scutes eae 289 
Colored light affecting drying 
Age a0 ak ee oe eee 119 
Colorimeters) 2c iecs.. tae eee PAE 
Commercial para red........... 734 


Comparison of lithopones for dar- 


kening. jc:i025 «4s Bee eee 212 
Consistency of paste paints... .49-51 
Consistometers. 3.) .4lvs aes 37 
Constants of. ol1S.<4.-450e ee 401 
Controlling thickness of films.... 108 
Conversion tables. .........5 298, 299 
Copper paints, Methods of test- 

Ing, u's onleslelets Shee was) OSU 
Coumarone “PeSilivcy.. sone eee 497 


Croll method for tinting strength 302 
Croll-Jenkins accelerated testing 
cabinet... 24 ee oid ane oe 323 


Darkening of lithopone.......... 200 
Darkening of shellac solutions.. 531 
Definitions, A. S. T. M. Standard, 

of terms used in paint specifi- 

cations, \.~. cco eee 768 
Destructively distilled turpentine, 

A. S. T. M. tentative specifi- 

cations ‘ f0ts-.5% pan ee eee «s DOG 
Determination of rosin in shellac 520 
Diagram of Pfund cryptometer.. 16 
Dipping tank tests on film thick- 

ness 
Discoloration of interior whites 284 
Discussion of coarse particle de- 


terminations *) 4.4; 6ee eee 152 
Dispersion test for tung _ oil, 

Holley ...oss0.00) eee 433 — 
Doolittle viscometer............ 33 
Doping systems for airplanes.... 394 
Dried volume weight of pig- 

ments 05 Sessa eee 146, 147 
Driers affecting color....... i+. 


Driers affecting viscosity ...... 1179 
Driers, Effect of on enamels.... 
Driers in varnish. ..... noon : 
Driers, mixed, Analysis of. . aes 485 _ 
Drip method for melting point : 

Of rosin... -au sein ewe ees 5144 
Drying time cabinets, 124-126, 128, 130 3 


Drying time comparisons. 117 
Drying time of filmsie.n se ou . MG 
Dry ted lead... 23.15 areas 


du Pont scratch testing machine 69 — 


Eastman Universal Colorimeter. 232 — 
Effect of driers in varnish...... 1187) 
Effect of driers on enamels...... 467 
Elasticity or toughness, A. 8. T. 
M. tentative method of test for 
by addition of linseed oil..... 477 
Elasticity or toughness of var- 
nishes by addition of linseed 


PPE 417 
Elongation tests... .:.1ee sen eee 97 
Enamels, Black baking........ . 548 
Enamels, Effect of driers on.... 467 — 
Ester gum.o...550 eee 496 
Evaporation of solvents from lac 

quers, Speed of, so .9e eee «« Gen 


Index 


7735 


SSS SS SSS 


Examination of flaxseed........ 
Examination of lacquer pigments 
Examination of snirit varnishes 
patunation of _turpentine and 
ee rination of waxes and pole 

OS A er 
Exposure tests Petia 
Exposure tests, Forest Products 


Porting results. Ret end : 
Exposure tests on “Tacquer plas.” 

MN rs ia) ds) 5.6 eon 
Iixposure tests on resins... 502-5 
Jxposure tests on wood....... 
Exterior exposure of lacueqred 


mood panels,........... 


Falling weight—torsion type—ef- 
flux type—G. HE. type visco- 
meters 2 oe ee ae 

Fasig oil absorption number... 

Federal specification for roof 
RENE ig ce ye wn es eas 

Figuring bulking value of paints 

Film Spinning device............ 

Film testing machine. . 

Haim thickness........... 

Film thickness as affected by 
speed of withdrawal......... 

Fineness determinations, Thomp- 
son method. 


oo ee eeveee 


eee e eer ee eee eee ee 


Fixed oils and resins in varnish 


Flash point of lacquers 
Flash point of volatile flam- 
mable liquids, A. S. T. M. stan- 
dard method of test for...... 
Flaxseed, Examination of...... 
Flaxseed, Oil content of, Cole- 
man-Fellows method for...... 
Flowmeter for mobility tests.... 
Fogging tests on lithopone...... 
Foots in linseed oil.... 
Foots test, Jamieson-Baughmann 
method soe 
Forest Products Laboratory 
on painting lumber .... 
Fossil resins, Chemical examina- 
Men Ol. ...... 
Rerigniiy OF resins............ 


eooesr eee ee 


eoeee ee eee eee ee eee 


tests 


oeereere ee eee eee ee 


Gallie-Porrit apparatus for coarse 
particles 
Galvanizing tank tests.......... 
Gardner abrasion test..... 
Gardner accelerated testing wheel 
Gardner-Coleman oil absorption 
a 
Gardner color-change cabinet.. 
Gardner drying time meter..... 
Gardner flowmeter..... 
Gardner-Parks film tester....... 


ees eee ee 


569 
591 


455 


565 
569 


85 
309 


266 
284 
111 
5d 
97 


Gardner-Parks mobilometer..... 
Gas resistance of varnishes.... 464 
Gel test on aluminum stearate... 664 
Gold bronze powder..... a ed hae | 
Gloss measurements on paint 

89, 91-93 
Glycerin tests on lithopone... 209 
Green’s method for particle size 165 


39 


Green’s photomicrographic meth- 

CMA SURE ia, SNe tie ae AeA ea as ie ete LOD 
GUnl acerondés, 6.ccaa. « eae .. 496 
Hallett hiding power meter. 24 
Hardie recording spectrophoto- 

BIGLOT: Wecseciti a cine se We se Tien ataet HOU 
Hardness and abrasion resistance 59 
Hardness of synthetic resins.... 499 
Hardness tests on enamels...... 68 
Hardness tests on varnishes... 68 
Hess-Ives tint photometer...... 254 
Hexabromide test cooperative 

WOLK eS Ajes iL avioe ct eee ee tae 
Hexabromide test for linseed oil 415 
Hexabromide test on oils, Bail- 

WIV ESUA trestae pte sot ea SN eee Ua ee Me RD 
Hexabromide test, Steele-W ash- 

DUTY Vice elo aerate cee wohl @ he Pete CLO 
Hickson penetration consistency 

BOSE We ceetice ae es 4 et Nee Ve ee pny 
Hiding power and brightness 9, 662 
Hiding power and brightness of ; 

MISMeNES <)es os PS waved atee ee LOM ee 
Hiding power comparisons ....28-30 
Hiding power instruments..... 13 
Hiding power of pigments..... 27 
Holley dispersion test for tung oil 433 
Hopkins-Murphy accelerated test- 

INE pr CADINGE 2s Sime se ce de cee 
Howland colorimeter............ 240 
Humidity from various salt solu- 

Lis 2 Yon CaO Cltags ake PL ee ay gO 8 Fr" 
Impact testing machine........ 282 
Ingersoll glarimeter............ 90 
Inhibitive value of pigments.... 369 
Insoluble matter in rosin, Tests 

NEV ean Saari SaaS Hc gee uae (rem 
Insulating value of coated pipes, 

Testing Of iio ess Air hie Banya Hangs 4 1 
INSUlAtINne VAINISH ee 4 ce en oe 4D 
Insulating varnish, A. S. T. M. 

tentative method for testing.. 458 
Insulating varnish using ozone... 119 
Interfacial tension ..-.-..... 174, 177 
Iron and Manganese pigments, 

A. S. T. M. Standard methods 

Of: (ANALYSIS. 5/000 ~ Vin vana abe xchel a ted A 
Iron are tests for lithopone 208, 20S 
Iron are tests on white pigments 215 
Tyes -eolorimeter 0s viecmie sis see eee 
Jamieson-Baughmann foot tests 409 
Japans,: Black baking... .cc.s DBT 


Index 


776 
Kauri reduction test, Effect on 

SX DOSUTE Tal cx cbs ae alee 477 
Keuffel & Esser color analyzer... 244 
Keuffel & Esser spectrophoto- 

WOTOT: ys iis ccale ws ewe whee eed oe 244 
Laboratory hardness scratch 

LORTOR hod oleh ai odact re Cotas oo = Wee 61 
Lacquer analysis, Schemes for 

OG asks du: asl Oy eta eas eee 597, 605 
Lacquer coating, Low tempera- 

ture LOSS: ONy . is ate etnce este ae 617 
Lacquer diluents, Sampling and 

festine  ys.45 (eee ees eee 592 
Lacquered wood panels, Method 

Of “TOSting ./ ote csi eee eee 387 
Lacquer enamels, Testing of for 

physical properties........... 621 
Lacquer films, Physical tests on 616 
Lacquer liquids, Physical prop- 

erties Of. 5 ink nis vote eee 610 
Lacquer materials, Solubility and 

miscibility Of... situate es 598, 599 
Lacquer pigments, Examination 

OE Sa ov Wn 2p oa Se ee 691 
Lacquer. plasticizers, Exposure 

tests FONs sage ee oe eee 615 
Lacquer, Paper curl test for. 620 
Lacquer raw materials, Testing 579 
Lidequer Tess. ses ys ss wees 502 
Lacquer solvents and diluents, 

A. S. T. M. tentative methods 

of sampling and testing...... 592 
Lacquer solvents. Latent heat of 

vaporization ‘of |... sachs sees 627 
Lacquer solvents, Miscibility of © 

he phere ihe SER 598, 600 

Lacquer solvents, Refractive in- 

GEES OL ooh s oh ths See 610 
Lacquer solvents, Testing....... 592 
Lacquer solvents, Vapor pressure 

OF Er i ee eee 631 
Lacquer testing on wicker panels 388 
Lacquer vapors, Testing the flash- 

ines Of beets eee ee be oe ee 625 
Lacquers, Bending tests on.... 618 
Lacquers, Boiling point, flash 

point’ and: -gravity of222...49 610 
Lacquers, Brushing tests on.... 619 
Lacquers, Materials used in 

making. ....3 Pes ee ee ee 597 
Lacauers. Miscellaneous physical 

tests Olisi 5 a5 ConA vee ees 625 
Lacquers .on ‘wWO0ds tas -ain nw ees 387 
Lacquers, Physical tests on..... 612 
Lacquers, Roof spray test on.... 386 
Lacquers, Sanding tests on...... 620 
Lacquers, Speed of evaporation of 

solvents Trou... svn eaee ee 637 
Lacquers, Spray test on........ 619 
Lacquers, Tests of on metal.... 586 
Lampblack sa..3 6. 20a ee ears ray 
Latent heat of vaporization of 

lacquer solventS=. 0. cise ees 627 


Laurie-Bailey hardness apparatus 59 


Leaded Zine oxide............ 700 
Linseed oil addition test for 
toughness or elasticity of var- 
hishes.. s..8 ieee Are We . ATT 
Linseed oil, Boiled......... saws een 
Linseed oil, boiled, A. S. T. M. 
tentative specification for..... 411 © 
Linseed oil, Foots 1nl¢veean eee 405 
Linseed oil, Hexabromide test for 415 
Linseed. Oil, Raw... 2. 2esee seen 402 
Linseed. oil, ‘raw; TAs Sotieoeee 
tentative specification for..... 403 
Lithopone 4 is 6. sees ees 701 
Lithopone light resistance...... 193 
Livering of varnishes..... adie 
Lovibond tintometer............ 229 
Low temperature tests on lac- 
quer coatings: ...ci. ees ee 
Maerz and Paul dictionary of 
COlOT. 04s te bene ee ee 218 


Maintaining color standards 256-258 


Martens photometer........... 27-29 
MeMullin accelerated testing 
cabinet | .:.:. 233 ee eae eae 324 


Melting and softening point of 
rosin ..<.s) ae eee 512-515 


Mercury-quartz tube tests on litho 


PONE — ss dele we wa ce eee 195 
Metal paint issGe eee eee ee 369 
Metal, Preparation of for test.. 371 
Metals and solvents, Effect of 

upon darkening of shellae solu- 

tious’. sobs oto eee ee ee ey 531 
Mineral iron oxide. se aie ~. hae 
Mineral. spirits 56.5 ene eee 564 
Mineral spirits, A. 8. , M. tenta- 

tive specifications for... eax. 564 
Mineral spirits, Examination of 551 
Miscellaneous methods of test- 

ting materials... eae . 649 — 
Miscellaneous physical testing de- 

ViC@S 2%. cas) (ome eee 281 
Miscellaneous physical tests on 

lacquers:..« > +++ epee ee ee 625 
Miscellaneous tests on varnishes 465 


Miscibility of lacquer materials 
ats lea Oe 598, 
Mobility of lithopone ake ee 
Moses-Harris charts..... 
Munsell Atlas 
Munsell syst@m..k wiece es sees 
Nitrocellulose, A. S. T. M. recom- 
mended tentative specification 
for . 587 


Nitrocellulose, Bulking value of 590 
Nitrocellulose, Soluble.......... 587 
Nitrocellulose solutions, Toler- ; 

ance of to diluents....... 590 — 
Nitrocellulose, Stability test. for 582 x 
Nitrocellulose, Viscosity of...... 579 © 
Nutting colorimeter....... . 2283 


599 

58 
224 
221 
219 # 


eeeeoe 


fohespe =a 


Index 


777 


Ochre, A. 8. T. M. standard spec- 
UNS 0 ea 766 

Oil absorption, Gardner-Coleman 
MEURIONE SCI WSs clas Fhe Wes See we LS 266 

Oil absorption of pigments... .260-265 


Oil absorption tests............ 259 
Oil content of flaxseed, Coleman- 
Fellows method fer.......... 570 
Semeeisreak test Os. .0...... 66% 407 
Pie OOUStATILS Of; 2.5, .%. 2.2.0.0 401 
Oils, Physiological action of.... 663 
Oleoresinous varnish........... 455 


Oleoresinous varnishes, A. S. T. 
M. standard method for test- 


I ei ee Se ok a oe 455 
Optical dispersion test on tung 

ts oS eres eee y Scie vies «> 0 4 0% 435 
Benes SHellaGs. ws. eset eee ee 516 
Orange shellac, A. S. T. M. stand- 

aro specification for.......... 516 
Oxidation effects of ultraviolet 

REMI Wie ipie ake rule 5 o's» ae 190 


Ozone apparatus for drying var- 


I 2 ne eae ae 119 
fant ois, Analysis of......... 401, 
armies DiLuUmInOUS..,. <2... e260 535 
Palmerton accelerated testing 

OSU Se pS ae 326, 330 


Palmerton humidity ecabinet.... 122 
Panel racks for baking tests.. 294 
Paper curl test for lacquer.... 620 
Papers on physical testing...... 296 
Pari abrasion. test...........: 87 
Particle size of pigments, 165, 173, 660 
Particle size, Relation of yield 


OO nee A a 1738 
Particle size, sedimentation 

PREM re ees tae oss eh ee 1¢2 
Perilla oil, raw or refined, A. S. 

T. M. standard specification 

UE als db 2k at Sisto + «8s 443 
Merroleig SPITits 2 o..e5 eek 564 
Petroleum spirits, A. S. T. M. 


tentative specifications for.... 564 
Pfister method for color of resin 406 
Pfund colorimeter for white pig- 


Ee ios Gols a wb os ulig Gc kes 
Pete erypcometer ............ 14 
Pfund hardness meter.......... 82 
Buero) type resis. .........5... 496 
Photomicrographs of accelerated 

PORES a es ee ks ese le-o10; S01, D008 
Photomicrographs of coarse par- 

SEM ec a ccc oe 10s 158-160, 163 


Photomicrographs of exposed sur- 
SS San ae ere 363-368 
Photomicrographs of exposed var- 


Ie NG ests... ~ + sO00-O08 
Photomicrographs of hardness 
ra 63-65 


Photomicrographs of p2int pig- 
NR ee hoo gia, yo 5 wary 0 166-169 


id 


Photomicrographs of screens.... 156 


Physical properties of lacquer 
LCL Sein certeetssencay en ane Saeco wees 610 
Physical testing, Technical pa- 
WOTSAOH Gis hee ets ee teas Neene 296 
Physical tests on pyroxylin lac- 
UCTS etait Ss oir ater ele 612 
Physical tests on stripped lac- 
POTTS ee wien org hee Sota s ees 616 
Pigment analysis, Calculation of 
PSU LL RRR, cOca es SRS I els saad he 693 


Pigment photomicrographs. ...166-169 
PRremenfp (COS UUILGs: s svete ate cs see's 276 
Pigments affected by ultraviolet 216 


Pigments, Analysis of 


CUR TD ERWE EE yep een ace Beet fe Om ae mF 688 
BMELMOUY c, OS IOC ox jarsdan.'s--3. 2 kets 684 
PCAN wl cereale Gc ah ee uci ssaehire wo kas ee 709 
DALE. (SOLU DEL See 2 ston aes 688 
DS TRC lee. oo esl watts erat a tes ans ara ahd ok 756 
PEs COWL Go tre areca ra ot stencil anit 742 
DIUBSEIOO Chic. ocnara yeah cinuetere nue ele 743 


blues, Prussian, Chinese, Ant- 
werp, Milori, Bronze Steel.. 740 


DIE sULETAALING eo cei e-otenaade fe TAL 
CACHING CUG cS cs onto e elses 728 
calcium pigments....708, 709, 715 
CFIC SOLUDIG oc. 5. slerateie ee oe 688 
CUT EEO Tee te nhe odes fe 9 aoa ang eee eta cnaes 756 
Sarit (LOSI Gs 20m oisig cae 703, 713 
chrome green ....... 744, 745, T46 
chrome oxide green. ........« 749 
ehrome, Vellow os; baieeeece 737 
GCOLDTS, sh OTPAT IG. Soy iaaiascn whine 731-34 
CUDTOUS OKICE. TE. wine s,0c8 oo x 730 
STAD ILO tee sane set oie. de yeicas genase 756 
PRhEa a7 PO Sa5 5 esti s eters ese ee es 761 
lead chromate, basic....... <..- tod 
leat.) meta llices cw peat a Abbe T04 
BP Ss POU iy sone Se oae. Gre ie eae me T19 
lead, red, Figg method........ T22 
lead, red, Schaeffer method .. 725 
UENO PONG: a sess y aes rend « scestyatent sue 706 
lithopone, cadmium........... 729 
masnesium,, soluble ..3, «2 <4. 689 
Pit &l ANE Gs Robe an pe no Uae ERE et 763 
Prince’s. metallic. ;40. 005 < nals os 761 
TOU ONG vs eek ee alana 761 
RELETIAIITRS oon 5 Sof tists ene oaks uae 728 
SL BLT fe: she ech vy eke aciicaes Hu be ee ites 764 
BRET UEC ieee hk ep et eka viadermcokerole elas 709 
suifate: soluples. naan cease 690 
STULL HOGS a ee eae katare wih nce eee 690 
sulfur compounds, soluble..... 690 
ODE GPR aN G WE2 D0 emir Ph enc cee A 691 
EL CART Gs eels oe tetas ape acateee 710 
TSE A TIS «5 erclraciay «thiol mis Tate caer ete 761 
WM DOP sas ces Sie Sole Ree re eae 764 
Venetian res oe.) ates ate ainsi 764 
WEE TA LILOTE ie sc seed sieve ta ee peas 730 
vermillion, American ......... text: 
WATER: SSOLUDLG io. yctete cine ands ole 691 


778 


Index 


Pigments, Analysis of—continued 


white lead, basic carbonate 703 
white lead, basic sulfate..... T04 
WHITE TOUGINE: 250. G5 te aan s oe 702 
BING .PHTOMALE csc eek ae ee eee 748 
PATIO PORCIEU D2, 1s asa rie ety bso oe 705 
BING: ORTAE hye sare Geile o oie a,deetatne TO6 
Pine, COAL soe od oes 5 egeetieees 688 
Pigments, Color number of...... 
Seehof Ca a - . 649, 652-654 
Pigments, Inhibitive value of.... 369 
Pigments, Oil absorption of. .260-265 
Pigments, Particle size of....... 660 
Pigments, Physical properties of. 300 
Pigments, Settling properties of. 659 
Pigments. Transmission of ultra- 
violet light through....... 187, 188 
Pigments, Wetting properties of 654 
Physiological action of oils.... 663 
Plasticizers, Laequer, Exposure 
LOSUS CON <<a: als cles 2 a epee ete 615 
Polishes. Examination of....... D795 
Polymerized oils and resins in 
WEPTUISD: o-..a. bo Meee eee ee 450 
Polymer test for tung oil... 3:2. 435 
P.. PP: G. consistency test... 2% eS 


Practical color standards ....256-258 
Preparation of films for hardness 


GOST ache eect aetene wore ewe sere eh 
Preparing metal for exposure 

TeStS As eee at CR eee Sil 
Primers for wood pene sae are 352 
Print. test device. ok eee 281 
Prupsiate- DING... +c fseca eet Sane, LEME 
Pure Chrome ereen’.:.5 25.0.5 668 749 


Pyroxylin coatings, Analysis of.. 595 
Pyroxylin coatings, Materials pre- 


BONE IN wy cys os loe Rat sea eee 597 
Pyroxylin lacquers, Physical tests 

(its coon sar, SCN e wists ted eet eee 612 
Rack for draining panels...... 295 
Raw materials in lacquer...... 579 
Ret ogi e o i vanes oats «etl eee 496 
Red: leatl ccs eee eee 718 
Red lead primers for wood..... 352 
Reduced chrome green......... 750 
Refractive index >:...% .e5 ee ee 9 
Refractive index of lacquer sol- 

Vents. Ss Seg Bes ere ne nee 610 


Refractive index of white pig- 


MOUNT Keene ee : Suline: Spee ae 
Refrigeration testing cabinet. 288 
Refrigeration tests on paint.. 287 


Relative method for particle size 173 
Resins, Color camparisons of.... 510 
Resin, Coumarone ....... 
Resin and oil solutions, 
ures on 503 
Resins, Exposure tests on. . 502-509 
Resins and fixed oils in varnish 449 
Resins. Fossil, Chemical exami- 
nation-Of..7.. Ae Pe eerie S| pak 


Expos- 


492 


Resins, Fusibility of..........s. om 
Resins in lacquers...i.:.20...0 eee 
Resins, Miscellaneous ......496, 497 
Resins other than fossil........ 495 
Resins and polymerized oils in 

varnish: ve... cee (oly ean 
Resins. Solubility of..... 
Resins, Solubility and miscibility 

of in lacquer solvents... .599, 600 
Resins, Synthetic, Exposure tests 

On * -4)d aes oo eels akg 0 ores Oe 
Resins, varnish, ‘Analysis of.... 488 
Ridgway color system... mater |, 
Roof coating, Analysis and spec- 


ifications. for ©. s,s. 5 sates ae 
Roof coatings, Federal mene 

tion fOr ..65.627 eee . 546 
Roof tests on galvanized pipe. «es O84 
Rosin determination in shellac 

rt) ME oe oe 520-529 
Rosin drip method. Hic cee eee eee 
Rosin in- shellac, Determination 

Of 2 SS oe ee ra rriy bogie. 
Rosin, Softening and melting 

point Of <. aeeeuer veeacsve OL2-ts 


Rosin, Tests for insoluble matter 511 
Rosin, Toluol insolubility clarity 
test for ne oe LR Rie oe 
Rub-out test for oil absorption.. 260 
Rust inhibitive value of pigments 369 


Salt water, Effect of on metals 376 
Salt water, Effect of upon painted 
metals + pele Ht Banat 
Sandarac resin...... ve bit eas se 
Sanderson drying time meter... 113 
Sanding tests on lacquers...... 620 
Sapphire point hardness test... 62 
Schemes for analysis of lacquer 
: eee -areeeee .. 597-605 
Secondary reference standards 
for, Colt... 445035 scam uae ewes 
Sedimentation method for par- 
ticle -Siz@ .264 san eee oe 
Service tests on varnishes...... 
Settling properties of pigments.. 
Shaded paper for hiding power 
tests -.... cs tatele ete een 
Shellac” sx so, eee 
Shellac analysis. ........- 
Shellac, A. S. T. M. standard 
methods for testing. 
Shellae, Orange, <A. S. T. M: 
standard specification for.... 
Shellac Rosin in, Determination — 
Of gh sneame 6iack pe 
Shellac solutions, Darkening of.. 
Shellac varnish, A. S. T. M. ten- 
tative method for testing.... 
Shellac, Wax in. A. S. T. M. 
tentative method for determi- 
nation of 


coo eevee eee 


eoeoenreev ee 


eos ee 


wee eveeee 


523 


oeee er eee 


aie 


.. - 489-500 © 


sno ve es se 
Ships paints, Method of testing.. 377 


i i canta ech: Wik ae cian Ta acai a eaten ee a ld i a ae hd eR 


ce 
7 


Deh ae 


Index 779 
Smoothness of white opaque pig- Synthetic resins, Solubility and 
a ee ie ok uO properties’ Ofes Flees ols 498-500 
Saal age oe pont Aa ee 515 Tanks for testing painted metal 
ie See SUR MERR OO peel awe Sa Ae nae i: S74 
Solubility of lacquer materials Temperature conversion tables.. 299 
eae te 8 = = sl ea 598, 599 Temperature humidity control 
Solubility and properties of syn- CALIROLS ivan erie eS ol nea re ibe 
Siete TESS, oe cs iste ee 498-500 ‘Tensile strength of films....... 102 
Solubility of resins............. 500 Tensile strength tests. 97 
Solubility: of tung oil polymer.. 435 Terms used on reporting exposure 
Solvent in varnish............. 448 TESTS cee cece eee cee eee eee eens 354 
Solvents. and metals. Effect of Testing automobile black baking 
upon darkening of shellac solu- CIISUOLENE ee Gar Good, "fe aacrneone ete atic 548 
COR SS eae 531 ‘Testing colors for tone and 
Solvents, Speed of evaporation of strength SMalisisieliatausl Sele ca lsinet Rete caiale 305 
Srey IACHUELTS «0... sss a ss.. ia Leste COMPEr SPaINESs....7. pias yte 380 
Soya bean oil, raw or refined, A. Testing durability of airplane 
S. T. M. tentative specification doping systems.............. 394 
oe See 439 ‘Testing effects of metals and sol- 
Specific ‘gravity, A. S. T. M. vents upon darkening of shel- 
ath le Ea el 136 FAC aypSONILIOUS > cere hare cine 6 5 ahs dol 
Specific gravity of lacquers...... 709 «= Testing gas resistance of var- 
Specific gravity of paint liquids 147 PLS eter ra ras tees 2/6 Wks woes eke a 466 
Specific gravity of pigments .... Testing impact effects "mon films 282 
(a ........ 144,145, 146 ‘Testing influence of thinners.. 477 
Specific gravity, whirling method 143 Testing insulating value of 
Specifications for aluminum ste- paints Saket iiatareuehe ceive lekdicheteiatetete (at stee 286 
0 Te BG Sn 671 Testing lacquer enamels for phys- 
Specifications, A. S. T. M., for RAI DLO DOE LOR Sts rota lageon tet eate 621 
Pearse particles ............. 151 Testing lacquer solvents........ 592 
Specification, A. S. T. M. for spe- Testing livering of varnishes.... 466: 
1) SOS a a 136 Testing metals with accelerated 
Spectrophotometers a eee aeawiag U7 POO LATS tals Sa el Geode a pw lea ame 374 
Spectrophotometer, Hardie...... 259 Testing nitrocellulose lacquers on 
Speed of evaporation of solvents PUM GA me oie aie tee oo, coil. a toon © casi Win 386 
Brome 1acguers. ©. 2.05.2... ees 637 Testing paints for aluminum al- 
Speed of evaporation of varnish JOYS secre e cece erect eens 381 
ee... 471 Testing paints for cement  sur- 
Spinning device for film thickness 109 faces, Accelerated method of.. 387 
Spirit varnishes, Examination of 453 ‘Testing paints for refrigeration 
Spray test on lacquers.......... 619 TOSSES Aiea ae Sled os Ooms 287 
Stability of nitrocellulose...... 582. ‘Testing physical properties and 
Standard oil absorption test.... 260 solubility of synthetic resins.. 495 
Steam distilled turpentine, A. S. Testing raw materials in lacquer 
T. M. specifications for...... 556 MARWEACLULE. — feraste <ipts wise wees 579 
Steele modification for rosin in Testing resistance of lacquers to 
er 529 bending ....--.+-. sees esse ees 618 
Steele-Washburn hexabromide Testing speed of evaporation of 
|S RINE SS ee en 416 WATTS, thiNners 1. 6G. os. ee > 471 
Strength and tone of colors.... 305 Testing temperature of colored 
Stutz apparatus for ultraviolet building materials...) san% +. 5 289 
NS Fag ie seals sta.e «9's 0 185 Testing the acid value of var- 
Super-accelerated alkali-water nishes ..... SRM I RAR ar Ge . 465 
a a NE a a 391 Testing the bulking value of 
aeece en aaa 180 MiPFOCEUUIOSE "ee eying s Hae 590 
Re ees sir agl ish Akl s ns ere Gictras Cn erdrta San 
Swinging beam hardness test.... 70 Testing the light resistance of 
Synthetic resins, Exposure tests . lithopone RA Ae Cay ae MEA ee 198 
re rr 502-509 Testing the rust inhibitive value 
Synthetic - resins, Hardness of.... 499 Of -DISMHONTIE 7.025% vnc eee hes 369 


780 


Testing toxic compositions to pre- 


Tent fOnLING.. scars eee O17 
Pesting: tune ~ Ollss.4 = vale See wale 431 
Testing white opaque pigments 

for physical properties....... 300 
Texture of pigments........-+e% 276 
Thickness of wet films.......... 103 
Thinners, -Influence of... 00 ess 477 
Thinners, varnish, Speed of evap- 

OTREION (Glcws. Are. ss ager ate 471 
Thompson classifier for paint pig- 

TOCNTS ee ou 5 5 Fela ee eee 161 
Tinting power vs. hiding power 27 
Tinting strength, Barton’s method 

ij a ie ot Agel ways Bae i: 303 
Tinting strength, Croll method 

TOY . -«ctoainbe Ula ah oe a aes pe 302 
Tinting strength of titanium pig- 

TOU ESE ce ple 6 a eae ea eae 303 
Tinting strength of white opaque 

DISHES 2. ue. += + sae eae 301 
Titanium-barium pigment....... 701 
Nitanitim pigments. of. .kee ene 710 
Titanium pigments, Tinting 

Strength -of 7) Sisk cls ete es 303 
Toch test for Tune Oilss. cea nu 435 
Tolerance of nitrocellulose solu- 

tions. £0 diluents... se seen ee 590 
Toluol insolubility clarity test for 

TOSEH: so. 4 ee es bee o11 
Tone and strength of colors..... 305 
Toughness or elasticity, A. S. T. 

M. tentative method of test for 

by addition of linseed oil...... ATT 
Toxie compositions, Testing of on — 

WOSSGIS Ty is d-aichwed © Shaun ge piace 377 
Transparency of pigments to 

ultraviolet: radiation... ...< <=... 184 
Tri-metal’ Primers: 2 vias. sie s «aie 352 


Tung oil, Apparatus for testing.. 431 


Tung oil, Bolton’s method for 

PORTING 754545. ¢ pea ee 434 
Tung oil, Holley dispersion test 

FOR ca Wise ee ae ee i eee 433 
Tung oil Optical dispersion of.. 454 
Tung oil, Polymer test for...... 435 
Tung oil, raw, A. S. T. M. tenta- 

tive specification for . 2.5 s2u.5 427 
Tung oi}, Toch test for io... eee 435 
Tung oil varnishes, Alkali in- 

crease: tést c10T) iike nA tig 6 oe 470 
Tungstone point hardness test.. 66 
Purpentine 45.5 saves eee ees DOT 
Turpentine, A. S. T. M. standard 

methods of sampling and test- 

15 6 pe MM ar CDRP an pis Ons 2 BST 
Turpentine, Destructively distill- 

CH WOU Sake pele s 7, eevee en nee 
Turpentine, Examination of.... 551 
Turpentine, Gum spirits of.... 556 
Turpentine, Steam distilled...... 556 


Index 


named 


Ultramarine blue.......... ss ols See 


Ultraviolet effects on colored pig- 
ments 


WIdS 3... Hen ae ee 186 
Ultraviolet light effects on pig- . 
ments. +04 18a ee ar 215 


Ultraviolet light oxidation effects 

Ultraviolet light studies on paint 
liquids 

Ultraviolet light studies on paint 
pigments > «i.e wae . Aor 


Ultraviolet transmission of pig- 
ments 


Vapor pressure of lacquer sol- 


Vents. ® srw eee ne a cies we) GU 
Varnish, Acid number of........ 447 
Varnish, AnalysiseGt,.77 <:.55e . 447 
Varnish, “ASho ids... eee ee 
Varnish, Exposure tests....... . 362 


Varnish, Fixed oils and resins in 449 
Varnish, Insulating, A. 8S. T. M. 
tentative method for testing.. 458 
Varnish, Polymerized oils and re- ~ 
SINS . 1D (. s.5 sass. oie eee 
Varnish resins, Analysis of .... 
Varnish, Shellac, A. 8. T. M. ten- 
tative methods of testing.... 
Varnish, Solvent ine, .-es te aoee 
Varnish thinners, Speed of evap- 


oration “Of +0 Nei ee ee 471 
Varnish viscosity affected by 

driers... 6.3% eee eee 11Ts 
Varnishes, Bituminous.......... 536 
Varnishes, Color standards for.. 479 — 
Varnishes, Gas resistance of.... 466 — 
Varnishes, Influence of thinners 

UPON: 45°s b e-ore. doen eae ATT 
Varnishes, Linseed oil addition 


test for toughness or elasticity 477 — 


Varnishes, livering Of.........- 466 
Varnishes, Miscellaneous tests on 465 
Varnishes, oleo-resinous, A. 8. T. 

M. standard method for testing 455 
Varnishes, Spirit, Examination of 4538 
Varnishes Testing the acid value 


i) Nr 465 
Varnishes, Tung oil, Alkali in- 
crease~ test’ TOF. <7, saceunisee 468 
Vehicle, Effects of on light resis- 
tance of lithopohe.......4.0s8 198 
Viscometer conversion charts.... 37 
Viscosity conversion table...... 35 
Viscosity of lacquers.......... 41 
Viscosity of nitrocellulose..... . 579 
Viscosity of paints... -seeeee . 42 
Viscosity, plasticity and mobility, 
Instruments. for... ae eee 3s 2a 
Viscosity vs. mobility compari- 


sons 


ie ee te oe 


ee ee 
eet aan Sd 


an erence ane ng Ae 


Fi 


pS ks bos 


+. 


ee ee eG ares 


‘as 


SS sh BS eS Nig eT Beli alah nt a aes he 


ie 


Pia aah eg Pah yr 


Index 


781 


Leen ERE aeacaeeemmeaeenczeemeeeeeeeemmeeaesaeaa mamas cca ascaaacaaaaaaaaacacaaaammaaaaamamamsmcacmaaamamaaal 


Volatile flammable liquids, Flash 
point of, A. S. T. M. standard 


mernod Of test for.........6. 
Volume and weight cup......... 
Walker-Hickson accelerated test- 
0 OE 
Walker-Steele-Hickson humidity 
NN Cee aie gona 9 ¢ 00 6.80 ee 
Men SCNCLING. 2. cn ccs se pene ee 
Wax in shellac, A. S. T. M. ten- 
tative method for determina- 
ict ec ya 0.e:e 'ci'e. 00 
Waxes and polishes, Examina- 


TR ee es Ss ait ecw cle ee 


Wetting properties of pigments, 
Testing of with different liquids 654 


White linseed oil paints....... 676 
WV LO DIS UIENCH sac case tadele 5 ohama oa 702 
Wiesel method for viscosity of 
MILTOCOINTIOBC. same wie Ss Gasset ate 579 
Wilkinson color-sound system... 221 
Wilkinson pencil test for hard- 
HORS ae id s siaeire +s cee wiaks 6 eh eke 61 
Wood panels for testing paint.. 342 
Ce UTI alekc so aeteie etaces fee ate 6 496 
Yield of paint formulas........ 146 
Yieldof saint liquids sc .00 +« 150 
AACR RC eas Sache 's a) & arn elateeoeocage ee 699 


~~ 


S : * 
y 
- 
# 
- 
~ 
, 
. + ~~. 
4 
a> 
‘ P 
As = 
= > on 
> re i 
-~ * ihe 
i 
¢ 
& 
- _ a 
. “ ‘ 
y 7" ut 


STANDARD AND MASTER SPECIFICATIONS 


For USE OF DEPARTMENTS AND INDEPENDENT ESTABLISHMENTS OF THE 
U. S. GoveERNMENT 
OFFICIALLY ADOPTED OR PROMULGATED BY THE 


fi 


FEDERAL SPECIFICATIONS BoAarRD 


*- 


- The specifications issued to date, in so far as they are available at the 
Government Printing Office, have been bound in this volume. The list is 
Sates below : : 


Rateirae’ cations 
ES (Ciroular Board 
re Edition Title 
2 4a Third—Oil, Linseed, Raw. 
5  Second—Basic Carbonate White Lead, Dry and Paste. 
6 Second—Basic Sulphate White Lead, Dry and Paste. 
tb ‘Third—Turpentine (Gum Spirits of Turpentine and Steam- 
____ Distilled Wood Turpentine). 

|  Second—Zine Oxide, Dry and Paste. 
_ Second—Leaded Zine Oxide, Dry and Paste. 

- Third—Paint, White, and Tinted Paints Made on a White 

Base, Semipaste and Ready Mixed. 
_ Second—Red Lead—Dry and Paste. 
_ Second—Ocher, Dry and Paste. 
- Third—Paints, Iron Oxide and Iron Hydroxide. 
‘Third—Paint, Black, Semipaste and Ready Mixed. 
a Third—Green Paint, Semipaste and Ready Mixed. 
- Second—Volatile Mineral Spirits for Thinning Paints. 


‘Second—Composite Vehicle for Thinning Semipaste Paints 
when the Use of Straight Linseed Oil is not Justified. 


_ Fourth—Varnish, Spar, Water-Resisting. 
. _ Second—Asphalt Varnish. 
| ‘Second—Liquid Paint Drier. 
_ Second—F lat Interior Lithopone Paint, White and Light 
pints’ | 
Second—Interior Varnish. 
pt. 25, 1923.—Water-Resisting Red Enamel. 
pt. 19, 1923.—Gloss Interior Lithopone Paint, White and 
i Feb. 20, 1924. erttaniunm Pigment, Dry and Paste. 
ps - Second—Paint, Olive Drab (Semipaste and Ready-Mixed). - 
May 9, 1925.—Outside White Titanium-Zine Paint, Semi- 
paste and Ready-Mixed. 


ae May 9, 1925.—Putty. 
Feb. 9, 1926 Shellac, Flake Orange. 
| Feb. 9 1926.—Varnish, Shellac. 


FOS 29, ‘1927. Ne einkoine Vellow cel Medium, and 
ey Dry, Paste in Oil, and Paste in Japan). 


U. S. Gov't 
Master 
Specification 


44 No. 4a 


DEPARTMENT OF COMMERCE 
BUREAU OF STANDARDS 


George K. Burgess, Director 


CIRCULAR OF THE BUREAU OF STANDARDS, No. 82 


[3d Edition. Issued April 26, 1927] 


UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
OIL, LINSEED, RAW! 


FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 4a 


[Revised March 5, 1927] 


This specification was officially promulgated by the Federal Specifications 
Board on February 3, 1922, for the use of the departments and independent 
establishments of the Government in the purchase of raw linseed oil. 


[The latest date on which the technical requirements of this revision of this specification shall become 
mandatory for all departments and independent establishments of the Government is June 6, gee They 
may be put into effect, however, at any earlier date.] 


CONTENTS 


1 
1 
Ill. Material and workmanship__.._._-.....___--___- ae lan aw ne Oe 2 
ewe aeaieras TodUsronients. ee et ene “Os MNOS. BiG 2 
Deewana mermnsertents. cee ee a ee ee on 2 
VI. Methods of sampling, testing, and basis of purchase_..__.__.___-- 2 

a MEE AS ie bc te pi AE ba aes ee a 2 
a Se A ee ee ee 3 

pg twas) lle iy i Ma Sk Ai Ld Gias Sk ae io 6 

*Pesenieros Purchase. 5.0). 09 [D272 LL Doss leurs 8 

DP RpaeenC iGreen t  e o tee me wh AM Re pei 8 
MME TRS A ee TR a SO ae Se US NPE AEROS SHE > 8 


I. GENERAL SPECIFICATIONS 


_. There are no general specifications applicable to this specification. 


II. TYPES | 
This specification covers two types of raw linseed oil: A, normal 
iodine number; B, high iodine number. 


1 For boiled linseed oil see United States Government Master Specification for Boiled Linseed Oil, Fed- 
_eral Specifications Board specification No. 475a, (B.8. Oircular No. 330.) 


43256°—27 


2 CIRCULAR OF THE BUREAU OF STANDARDS 
Ill. MATERIAL AND WORKMANSHIP 
See detail requirements. 
IV. GENERAL REQUIREMENTS 
See detail requirements. 
V. DETAIL REQUIREMENTS 


Raw linseed oil shall be pure oil expressed from flaxseed, and shall 
conform to the following requirements: 


oots: 

Mente wOll..- cpekcstckee ec anne act asoese eee oe neers per cent by volume.- 1,0: “eekeaseeeene 
“@UChEU (ets Bay 0 NOI eee ae CRN e a oe ORE mMEE Reg Sy LN ale niry mene AE ANE fp ooee 4.0" cLiccesoweesoe 
Specific gravity 15.5/15.5° C___....------------------------------- 2-02 neon n ee ene . 935 0. 9300 
‘Acid nam bet. ob eb eee coke cane ke pees Sateen 5 Soe, eM ee 

Saponification number___.....----------------------------------------+2+2+5--20- 195. 0 189. 0 
Unsaponifiable matter-......--.-------------------------------------- per cent_- Te OO fetes ae 

Todinie number 1.2 ecb nce bine cece ees ae ae et eee eee boeken Wits kee eee 175. 0 
Loss on heating at 105 to 110° C....---.--..------.-+.----------------- per cent... (Aba Hess de eee 
OOlOT kk dade owe dwn nk wn sucdapeeccamcetonsss ses sap eee ee nese eee Not darker than a 
freshly prepared solu- 


tion of 1.0 g potassium 
bichromate in 100 cc 
pure concentrated 
sulphuric acid (sp. 
gr. 1.84). 


1 When high iodine number type of raw linseed oil is specified by the purchaser, the iodine number must 
be not less than 188 and the oil shall conform to all of the other requirements. te 


VI. METHODS OF SAMPLING, TESTING, AND BASIS OF 
PURCHASE 


Deliveries will, in general, be sampled and tested by the following 
methods, but the purchaser reserves the right to use any additional 
available information to ascertain whether the material meets the speci- 


fication. | 
1. SAMPLING 


The method of sampling given under (a) below should be used 
whenever it is feasible to apply it. To meet conditions when (a) 
is not applicable, method (6), (c), or (d) is to be used according to 
the special conditions that obtain. Haat 

(a) Durine Loapinc or Tank Cars oR FILLING OF CoNnTAIN- 
ERS FOR SHIPMENT AT THE Factory.—The purchaser’s inspector 
shall draw a sample at the discharge pipe where it enters the receiving 
vessel or vessels. The total sample shall be not less than 5 gallons 
and shall be a composite of small samples of not more than 1 pint 
each, taken at regular intervals during the entire period of loading 
or filling. | ee Se | 

The sample thus obtained shall be thoroughly mixed, and from 
this composite sample three portions of not less than 1 quart each 
shall be placed in clean, dry glass bottles or tin cans which must be 


SPECIFICATION FOR RAW LINSEED OM, 3 


filled with the sample and securely stoppered..with new clean corks 
or well-fitting metal covers or caps. These shall be sealed and 
labeled distinctly by the inspector, and one delivered to the buyer, 
one to the seller, and the third held for check in case of dispute. 

(6) From Loapep Tank Cars or OTuer LarGEe Vessets.—The 
total sample shall be not less than 5 gallons and shall be a composite 
of numerous small samples of not more than 1 pint each, taken from 
the top, bottom, and intermediate points by means of a glass or metal 
container with removable stopper or top. This device attached to 
a suitable pole is lowered to the various desired depths when the 
stopper or top is removed and the container allowed to fill. The 
sample thus obtained is handled as in (a). | 

(c) Barres anpD Drums.—Not less than 5 per cent of the 
packages in any shipment or delivery of. barrels and drums shall be 
sampled. The packages shall be shaken, rolled, and stirred to mix 
the contents thoroughly. The samples from the individual containers 
shall be taken through the bunghole or holes not less than 114 inches 
in diameter bored in the head or side for the purpose. The appa- 
ratus for drawing the sample shall consist of a glass tube about 1 
inch in diameter and somewhat longer than the length or diameter 
of the oil container, a conical stopper that will fit the glass tube and 
is not more than )% inch long fastened to a stiff metal rod not more 
than 4 inch in diameter and not less than 4 inches longer than the 
glass tube. The stopper is lowered by the rod until it rests on the 
bottom of the cask, the tube slipped down slowly over the rod, and 
finally pressed on the stopper. By holding tube and rod, the column 
of oil can then be removed. This process is repeated until the 
required amount of samples is obtained, which shall be not less than 
2 gallons. This is mixed and handled as in (a). 

- (d@) SmMaut Containers, Cans, Etc., or 10 GaLLons or Less.— 
Smali containers, cans, etc., of 10 gallons or less should be sampled 
while filling by method (a) whenever possible. When method (a) is 
not applicable, it is mutually agreed that: In all cases the total 
sample taken shall not be less than 3 quarts. This shall be obtained 
by taking at least one package from each lot of not more than 300 
packages. The sample thus taken shall be thoroughly mixed and 
subdivided as in (a). 
. 2. TESTING 


All tests shall be made on oil that has been thoroughly agitated 
before removal of a portion for analysis. | 

(a) Foots.—General test—With all materials ‘at a temperature 
between 20 and 27° C., mix, by shaking for exactly one minute in 
a graduated tube, 25 cc of the well-shaken sample of oil, 25 cc of 
acetone, and 10 cc of acid calcium chloride solution. Then clamp 
‘the tube in an upright position and allow to settle for 24 hours. 


4 CIRCULAR OF THE BUREAU OF STANDARDS 


The temperature during this period should be between 20 and 
27° C. The graduated tube shall be of not less than 70 ce capacity 
and shall have at least 50 cc graduated in 0.1 cc. The diameter of 
the tube shall be such that the 50 cc graduated portion shall be not 
less than 40 cm or more than 60 cm in length. The volume of the 
stratum lying between the clear calcium chloride solution and the 
clear acetone and oil mixture is read to 0.1 ec or fraction thereof. 
This reading multiplied by four expresses the amounts of foots 
present as percentage by volume of the oil taken. 

Heated oil—WHeat a portion of the oil to 65° C., hold it within 
2° C. of that temperature for 10 minutes, then cool it to room tem- 
perature (20 to 27° C.). Promptly make the general foots test as 
described above. | 

Chilled oil—Heat a portion of the oil to 65° C., hold it within 
2° ©. of that temperature for 10 minutes, then place it in a clean, 
dry bottle, stopper tightly, and place in a cracked ice and water 
mixture (0° C.) for exactly two hours. At the end of this time place 
the bottle in a large bath of water at 25° C. and keep it there for 
30 minutes, then promptly make the general foots test as described 
above. 

(b) Spectric Gravity.—Determine at 15.5/15.5° C. by any con- 
‘venient method that is accurate within two points in the fourth 
decimal place. | 

(c) Acty Numper.—Weigh from 5 to 10 g of the oil. Transfer 
to a 300 cc Erlenmeyer flask. Add 50 cc of a mixture of equal parts 
by volume of 95 per cent ethyl alcohol and c. p. reagent benzol. 


(This mixture should be previously titrated to a very faint pink 


with dilute alkali solution, using phenolphthalein as an indicator.) 
Add phenolphthalein indicator and titrate at once to a faint per- 
manent pink color with standard sodium or potasstum hydroxide 
solution. Calculate the acid number (milligrams KOH) per gram 
of oil. . | | . 
(d) Savonrrication Numper.—Weigh about 2 g of the oil and 
transfer to a 300 cc Erlenmeyer flask. Add 25 cc of alcoholic sodium 
hydroxide or potassium hydroxide solution. Put a condenser loop 
inside the neck of the flask and heat on a steam bath for one hour. 
Cool, add phenolphthalein as indicator, and titrate with 0.5 WV H,SO,. 
Run two blanks with the alcoholic alkali solution. These should 
check within 0.1 cc 0.5 N H,SO,. From the difference between the 
number of cubic centimeters of 0.5 N H,SO, required for the blank 
and for the determination, calculate the saponification number 
(milligrams KOH required for 1 g of the oil), Sk ania 

(ec) Unsaroniriaste Marrer.—Weigh 8 to 10 g of the oil and 
transfer to a 250 cc long-neck flask. Add 5 cc of a concentrated 
solution of sodium hydroxide (equal weights of NaOH and H,O) 


tase 
a, 


Saat NE ER": 


1 


WRB Gp SND GRE ADT mi root NS 
ee ere Pe tet eee Pee Mae ie ty oleh 


SPECIFICATION FOR RAW LINSEED OIL 5 


and 50 cc of 95 per cent ethyl alcohol. Put a condenser loop inside 
the neck of the flask and boil for two hours. Occasionally agitate 
the flask to break up the liquid, but do not project the liquid onto 
the sides of the flask. At the end of two hours remove the condenser 
and allow the liquid to boil down to about 25 cc. 

Transfer to a 500 cc glass-stoppered separatory funnel, rinsing 
with water. Dilute with water. to 250 cc, add 100 cc of redistilled 
ether. Stopper and shake for one minute. Let stand until the two 
layers separate sharp and clear. Draw all but one or two drops of 


_ the aqueous layer into a second 500 cc separatory funnel and repeat 


the process, using 60 cc of ether. After thorough separation draw 
off the aqueous solution into a 400 cc beaker, then the ether solution 
into the first separatory funnel, rinsing down with a little water. 
Return the aqueous solution to the second separatory funnel and 
shake out again with 60 cc of ether in a similar manner, finally draw- 
ing the aqueous solution into the beaker and rinsing the ether into 
the first separatory funnel. 

Shake the combined ether solution with the combined water 
rinsings and let the layers separate sharp and clear. Draw off the 
water and add it to the main aqueous solution. Shake the ether 
solution with two portions of water (about 25 cc each). Add these 
to the main water solution. 

Swirl the separatory funnel so as to bring the last drops of water 


down to the stopcock and draw off until the ether solution just fills 


the bore of the stopcock. Wipe out the stem of the separatory 
funnel with a bit of cotton on a wire. Draw the ether solution 
(portion wise if necessary) into a 250 cc flask and distill off. While 
still hot, drain the flask into a small weighed beaker, rinsing with 
a little ether. Evaporate this ether, cool the beaker, and weigh. 
(The unsaponifiable oil from adulterated drying oils may be volatile 
and as a consequence may evaporate on long heating. Therefore, | 
heat the beaker on a warm plate, occasionally blowing out with a 


current of dry air. Discontinue heating as soon as the odor of the 


ether is gone.) 
(f) Iopins Numser.—Place a small quantity of the sample in a 
small weighing burette or beaker. Weigh accurately. Transfer by 


dropping from 0.09 to 0.15 g of oil to a 500 cc bottle, having a well- 
ground glass stopper, or an Erlenmeyer flask, having a specially 


flanged neck for the iodine tests. Reweigh the burette or beaker 
and determine the amount of the sample used. Add 10 cc of chloro- 
form. Whirl the bottle to dissolve the sample. Add 10 cc of chloro- 
form to each of two empty bottles or flasks like that used for the 


sample. Add to each bottle 25 cc of the Wijs solution and let stand 


with occasional shaking for one hour in a dark place at a temperature 
of from 21 to 23° C. Add 10 cc of the 15 per cent potassium iodide 


6 CIRCULAR OF THE BUREAU OF STANDARDS 


solution and 100 cc of water. Titrate with 0.1 N sodium thiosul- 
phate, using starch as an indicator. The titrations on the two blank 
tests should agree within 0.1 cc. From the difference between the 
average of the blank titrations and the titration on the samples, and 
the iodine value of the thiosulphate solution, calculate the iodine 
number of the samples tested. (Iodine number is given in centi- 
grams of the iodine to 1 g of sample.) ‘y 

(g) Loss on Heatine at 105 To 110° C.—Place 10 g of the: oil 
in an accurately weighed 50 cc Erlenmeyer flask and weigh. Heat 
in an oven at a temperature between 105 and 110° C. for 30 minutes, 
then cool and weigh. Calculate the percentage loss. This deter- 
mination shall be made in a current of carbon dioxide. 

(h) Cotor.—Prepare a fresh solution of 1 g pure potassium 
bichromate in 100 cc of pure concentrated colorless sulphuric acid 
(specific gravity 1.84). Place the oil and color solution in separate 
thin-walled clear glass tubes of the same diameter (1 to 2 cm) to a 
depth of not less than 25 cm and compare the depths of color by 
looking transversely through the columns of — by ernst 
light. 


3. REAGENTS 


(a) Acrtone.—Acetone that will pass the specification of the 
United States Pharmacopoeia. 

(b) Acto Caucrum Cutoripe SoLtution.—Saturate with calcium 
chloride a mixture of 90 parts water and 10 parts concentrated hydro- 
chloric acid (specific gravity 1.2). 

(c) SranparD Sopium Hyproxipz So.utTion.—Prepare a stock 
concentrated solution of sodium hydroxide by dissolving hydroxide 
in water in the proportion of 200 g NaOH to 200 cc of water. Allow 
this solution to cool and settle in a stoppered bottle for several days. 
Decant the clear liquid from the precipitate of sodium carbonate 
into another clean bottle. Add clear barium hydroxide solution 
until no further precipitate forms. Again allow to settle until clear. 
Draw off about 175 cc and dilute to 10 liters with freshly boiled 
distilled water. Preserve in a stock bottle provided with a large 
guard tube filled with soda lime. Determine the exact strength 
by titrating against pure benzoic acid (C;H;COOH), using phenol- 
phthalein as indicator. (See Bureau of Standards Scientific Paper 
No. 183.) This solution will be approximately one-fourth normal, 
but do not attempt to adjust it to any exact value. Determine its 
exact strength and make proper corrections in using it. , 

y (d) Auconotic Sopurm Hyproxrpr Soxvurion. —Dissolve pure 
X sodium hydroxide in pure 95 per cent ethyl] alcohol in the proportion 
of about 22 g per 1,000 cc. Let stand in a stoppered bottle. Decant 


a Te 


3 ee ee 
ae 


wm, ome son 
tract ete 


SPECIFICATION FOR RAW LINSEED OIL, a 


the clear liquid into another bottle and keep well stoppered. This 
solution should be colorless or only slightly yellow when used. 

(e) StanparpD Sopium TutosutpHate Sotution.—Dissolve pure 
sodium thiosulphate in distilled water that has been well boiled to 
free it from carbon dioxide in the proportion so that 24.83 g crystal- 
lized sodium thiosulphate will be present in 1,000 cc of the solution. 
It is best to let this solution stand for about two weeks before stand- 


Chemistry, Treadwell-Hall, vol. 2, 6th ed., p. 551.) This solution’ 


will be approximately decinormal, and it is best to leave it as it is after 
determining its exact iodine value, rather than to attempt to adjust 
it to exactly decinormal strength. Preserve in a stock bottle provided 
with a guard tube filled with soda lime. 

(f) Starcu SoLutTion.—Stir up 2 to 3 g of potato starch or 5 g 
soluble starch with 100 cc of 1 per cent salicylic acid solution, add 
300 to 400 cc boiling water, and boil the mixture until the starch 
appears to be dissolved. Dilute to 1 liter. 

(g) Porasstum Jopipr Souturion.—Dissolve 150 g of potassium 
iodide free from iodate in distilled water and dilute to 1,000 cc. 

(h) Wiss Sotution.—The preparation of the iodine monochloride 
solution presents no great difficulty, but it should be done with care 
and accuracy in order to obtain satisfactory results. There shall be 

in the solution no sensible excess either of iodine or more particu- 
larly of chlorine over that required to form the monochloride. This 
condition is most satisfactorily attained by dissolving in the whole 
of the acetic acid to be used the requisite quantity of iodine, using a 
gentle heat to assist the solution, if it is found necessary. Dissolve 
iodine in glacial acetic acid that has a melting point of 14.7 to 15° C. 
and is free from reducing impurities in the proportion so that 13 ¢ of 
iodine will be present in 1,000 cc of solution. Set aside a small portion 
of this solution while pure and pass dry chlorine into the remainder 
until the halogen content of the solution is doubled. Ordinarily it 
will be found that by passing the chlorine into the main part of the 
solution until the characteristic color of free iodine has just been 
discharged, there will be a slight excess of chlorine which is corrected 
by the addition of the requisite amount of the unchlorinated portion 
until all free chlorine has been destroyed. A slight excess of iodine 
does little or no harm, but excess of chlorine must be avoided. 

(1) Haur Normat Sutpauric Actp Sotution.—Add about 15 cc 
of sulphuric acid (1.84 specific gravity) to distilled water, cool and 
dilute to 1,000 cc. Determine the exact strength by titrating 
against freshly standardized sodium hydroxide or by any other 
accurate method. Either adjust to exactly half normal strength or 
leave as originally made, applying appropriate correction. 


a 
“i, 
ly 


/ 


ardizing. Standardize with pure resublimed iodine. (See Analytical , 


\ 


8 CIRCULAR OF THE BUREAU OF STANDARDS 
4. BASIS OF PURCHASE 


Material is to be purchased by weight or volume, as specified in 
the contract. When purchased by volume, 1 gallon of oil shall mean 
231 cubic inches at 15.5° C. 


VII. PACKING 


Packing shall be in accordance with commercial practice unless 
otherwise specified. 
VIII. NOTES 


This specification supersedes that part of Federal Specifications 
Board specification No. 4 (B. S. Circular No. 82, 2d ed.) which 
covered raw linseed oil. For specification for boiled linseed oil, see 
Federal Specifications Board specification No. 475a (B. S. Circular 
No. 330). The specification for refined linseed oil contained in 
Federal Specifications Board specification No. 4 (B. S. Circular No. 
82, 2d ed.) 1s revoked. 

For formulas and methods of using this material and information 
regarding the use of other specification paint materials, see Bureau 
of Standards Technologic Paper No. 274, entitled ‘Use of United 
States Government Specification Paints and Paint Materials.” 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROX 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFYICE 
WASHINGTON, D. C. 
AT 
& CENTS PER COPY 


Vv 


DEPARTMENT OF COMMERCE. 
BUREAU OF STANDARDS. 


S. W. STRATTON, Director. 


CIRCULAR OF THE BUREAU OF STANDARDS. 


No. 84. 


[2d edition. Issued July 3, 1922.] 


UNITED STATES GOVERNMENT SPECIFICATION FOR 
BASIC CARBONATE WHITE LEAD, DRY AND PASTE. 


FEDERAL SPECIFICATIONS BOARD. 
STANDARD SPECIFICATION NO. 5. 


This Specification was officially adopted by the Federal Specifications Board on 
February 3, 1922, for the use of the Departments and Independent Establish- 
ments of the Government in the purchase of materials covered by it. 


CONTENTS. 

b Page 
ee, a. eecuae « Boga’ deyad bean Gash 
EERO ARID ae Pee 5 esse v Poe gh Rees Da ghh a hagh os ba oe Pepe eee 2 
S-Laveratory examination of dry pigment: .. 002 ee a eas z 
as Laperatoipiexaminaionio£ paste. O06. aloe. Os lo IOM a. lk 4 
RIMES PA ee Soe Bae cs Oe Dey «cap wiry pte 4m AY Hid ylourd «\deinahy perece> 7 


1. GENERAL. 


_ Basic carbonate white lead may be ordered in the form of dry 
pigment or paste ground in linseed oil. Material shall be pur- 
chased by net weight. 

- (a) Dry PicMentT.—The pigment shall be the product made 
from metallic lead and shall have a composition corresponding 
approximately to the formula 2PbCO,.Pb(OH),. It shall be 
thoroughly washed after corroding, shall be free from impurities 
and adulterants, and shall meet the following requirements: 

106568 °—24 : 


2 Circular of the Bureau of Standards 


Color—Color strength.—When specified, shall be equal to that 
of a sample mutually agreed upon by buyer and seller. 


Minimum, | Maximum. 


Per cent. | Per cent. 
Coarse particles retained on Standard No. 325 screen.......... 0... cece eect eee tpn eect neers 1.0 
Teadl. carbomate. . icc 6 ics cc uk arsidns wccnd' nie 'o wilea ba elecutns > bie USN wis “ac.eaa Rear gs a 65. 0 75.0 
Total impurities, including moisture...... 2.2... 0. ese nuesees vanerrsesaecee ass ahenees naps sue 2.0 


(b) Paste.—The paste shall be made by thoroughly grinding 
the above-described pigment with pure raw or refined linseed oil. 

The paste as received shall not be caked in the container and 
shall break up readily in oil to form a smooth paint of brushing 
consistency. The paste shall consist of: 


Moisture ‘and other volatile matter. - 22550 os ee sce hw wee seat p pn nO ea a 
Coarse Sh ee and ‘‘skins’’ (total residue retained on No. 325 screen based on 
PITMEHE) oo oie eases eid be weinle ep Sip ery na lalace Win gre ebb relm mBrm i eiene © Ch set a eee en 


NotEe.—Deliveries will, in general, be sampled and tested by the following methods, but the purchaser 
reserves the right to use any additional available information to ascertain whether the ‘material meets the 


specification. 
2. SAMPLING. 


It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1,000 packages shall be taken as 
representative of the whole. 7 

With the dry pigment, this package shall be opened by the 
inspector and a sample of not less than 5 pounds taken at random 
from the contents and‘sent to the laboratory for test. When 
requested, a duplicate sample may be taken from the same pack- 
age and delivered to the seller, and the inspector may — a 
third sample to hold for test in case of dispute. 

Whenever possible, an original unopened container shall be 
sent to the laboratory with the paste; and when this is for any 
reason not done, the inspector shall determine by testing thor- 
oughly with a paddle or spatula whether the material meets the 
requirement regarding not caking in the container. (See 4 (a).) 
After assuring himself that the paste is not caked, the inspector 
shall draw a sample of not less than 5 pounds of the thoroughly 
mixed paste, place it in a clean dry metal or glass container, 
which must be filled with the sample, closed with a tight cover, 
sealed, marked, and sent to the laboratory for test with the 
inspector’s report on caking in container. 


Specification for Basic Carbonate White Lead, Dry and Paste 3 
3. LABORATORY EXAMINATION OF DRY PIGMENT. 


(a) Coror.—Take 1 g of the sample, add 10 to 12 drops linseed 
oil, rub up on a stone slab or glass plate with a flat-bottomed 
glass or stone pestle or muller to a uniform smooth paste. ‘Treat 
in a similar manner 1 g of the standard basic carbonate white 
lead. Spread the two pastes side by side on a glass microscope 
slide and compare the colors. If the sample is as white or whiter 
than the ‘“‘standard,’’ it passes this test. If the standard is whiter 
than the sample, the material does not meet the specification. 

(b) CoLOR STRENGTH.—Weigh accurately 0.01 g of lampblack, 
place on a large glass plate or stone slab, add 5 drops of linseed 
oil, and rub up with a flat-bottomed glass pestle, or muller, then 
add exactly 10 g of the sample and 45 drops of linseed oil, and 
grind with a circular motion of the muller 50 times; gather up 
with a sharp-edge spatula and grind out two more times in a 
like manner, giving the pestle a uniform pressure. Treat another 
0.01 g of the same lampblack in the same manner, except that 10 
g of standard basic carbonate white lead is used instead of the 10 
g of the sample. Spread the two pastes side by side on a glass 
microscope slide and compare the colors. If the sample is as 
light or lighter in color than the standard, it passes this test. If 
the standard is lighter in color than the sample, the material does 
not meet the specification. 

(c) COARSE PARTICLES.*—Dry in an oven at 105° to 110° €. a 
No. 325 screen, cool and weigh accurately. Weight 25 g of the 
sample; dry at 100° C.; transfer to a mortar, add 100 cc kero- 
sene, thoroughly mix by gentle pressure with a pestle to break 
up all lumps, wash with kerosene through the screen, breaking 
up all lumps, but not grinding. After washing with kerosene 
until all but the particles which are too coarse to pass the screen 
have been washed through, wash all kerosene from the screen with 
ether or petroleum ether, heat the screen for one hour at 105 to 
110° C., cool and weigh. 

(d) QUALITATIVE ANALYsIS.—Test for matter insoluble in acetic 
acid, zinc, calcium, etc., by the regular methods of qualitative 
analysis. 

- (e) MortstuRE.—Place 1 g of the sample in a tared wide-mouth 
short weighing tube provided with a glass stopper. Heat with 


1 For a general discussion of screen tests of pigments and data regarding many pigmentson the market, 
see Circular No. 148 of the Educational Bureau, Scientific Section, Paint Manufacturers’ Association of 
the United States. 


4 Circular of the Bureau of Standards 


stopper removed for two hours at a temperature between 105 and 
110°C. Insert stopper, cool and weigh. Calculate loss in weight 
as moisture. , 

(f) Tora, Leap AND INSOLUBLE ImpuRITY.—Weigh 1 g of the 
sample, moisten with water, dissolve in acetic acid. If any insol- 
uble residue remains, filter, dry at 105 to 110° C. and weigh as 
insoluble impurity. Dilute the solution to about 200 cc, make 
alkaline with NH,OH, then acid with acetic acid, heat to boiling 
and add 10 to 15 ce of aro per cent solution of sodium bichromate 
or potassium bichromate, and heat until the yellow precipitate 
assumes an orange color. Let it settle and filter on a Gooch 
crucible, washing by decantation with hot water until the wash- 
ings are colorless, and finally transferring all the precipitate. 


Then wash with 95 per cent ethyl alcohol and then with ethyl — 


ether; dry at 100° C. and weigh PbCrO,. Calculate to lead oxide 
(PbCrO, X0.69=PbO). Total lead may be determined by the 
sulphate method if preferred. 

(g) CARBON Diox1bE.—Determine by evolution with dilute acid 
and absorption in soda-lime or KOH solution, calculate CO, to 
PbCO,, subtract PbO equivalent from total PbO and ratey 
residual PbO to Pb(OH),. 

CO, X 6.072 = PbCO, 

C0, X% 5.072 =1ug 
PbO \1.1o7 =P pC 
PbO X1.08 =Pb(OH), 


4. LABORATORY EXAMINATION OF PASTE. 


(a) CAKING IN CONTAINER.—When an original package is 
received in the laboratory, it shall be weighed, opened, and 
stirred with a stiff spatula or paddle. The paste must be no 
more difficult to break up and show no more caking than a normal 
good grade of white-lead paste. The paste shall finally be thor- 
oughly mixed, removed from the container, and the container 
wiped clean and weighed. This weight subtracted from the 
weight of the original package gives the net weight of the contents. 
A portion of thoroughly mixed paste shall be placed in a clean 
container and the portions for the remaining tests promptly 
weighed out. 

(6) MIxING witTH LINSEED O1r,.—One busiineds grams of the 
paste shall be placed in a cup, 30 cc linseed oil added slowly with 


a 


Specification for Basic Carbonate White Lead, Dry and Paste 5 


careful stirring and mixing with a spatula or paddle. The result- 
ing mixture must be smooth and of good brushing consistency. 
(c) MoIsTuRE AND OTHER VOLATILE MatTrerR.—Weigh accu- 
rately from 3 to 5 g of the paste into a tared flat-bottomed dish, 
about 8 cm in diameter, spreading the paste over the bottom. 
Heat at 105 to 110° C. for three hours, cool and weigh. Calculate 
loss in weight as percentage of moisture and other volatile matter. 
(d) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 g 
of the paste into a weighed centrifuge tube. Add 20 to 30 cc 
“extraction mixture’’ (see Reagents), mix thoroughly with a glass 
rod, wash the rod with more of the extraction mixture, add 
enough of the reagent to makea total of 60 cc in the tube. Place 
the tube in the container of a centrifuge, surround with water 
and counterbalance the container of the opposite arm with a 
similar tube or a tube with water. Whirl at a moderate speed 
until well settled. Decant the clear supernatant liquid. Repeat 
the extraction twice with 40 cc of the extraction mixture, and 
once with 40 cc of ether. After drawing off the ether, set the 


tube in a beaker of water at about 80° C., or on top of a warm 


oven for 10 minutes, then in an oven at 105 to 110° C. for two 
hours. Cool, weigh, and calculate the percentage of pigment. 

(e) EXAMINATION OF PiGMENT.—Grind the pigment from (d) 
to a fine powder, pass through a No. 80 screen to remove any 
‘“skins,”’ preserve in a stoppered tube and apply tests 3(a), 3(d), 
3(d), 3(f), and 3(9). 

({) PREPARATION OF Farry Acips.—To about 25 g of the paste 
in a porcelain casserole add 15 cc of aqueous sodium hydroxide 
(see reagents) and 75 cc of ethyl alcohol, mix and heat uncovered 
on a steam bath until saponification is complete (about one hour). 


Add 100 cc of water, boil, add sulphuric acid of specific gravity 
1.2 (8 to 10 cc in excess), boil, stir, and transfer to a separatory 


funnel to which some water has been previously added. Draw 
off as much as possible of the acid aqueous layer and lead 
sulphate precipitate, wash once with water; then add 50 cc 
of water and 50 cc of ether. Shake very gently with a whirl- 
ing motion to dissolve the fatty acids in the ether, but not so 
violently as to form an emulsion. Draw off the aqueous layer 
and wash the ether layer with one 15 cc portion of water and then 
with 5 cc portions of water until free from sulphuric acid. Then 


draw off the water layer completely. Transfer the ether solution 


to a dry flask, add 25 to 50 g of anhydrous sodium sulphate. 


6 Circular of the Bureau of Standards 


Stopper the flask and let stand with occasional shaking at a tem- 
perature below 25° C. until the water is completely removed from 
the ether solution, which will be shown by the solution becoming 
perfectly clear above the solid sodium sulphate. Decant this clear 
solution (if necessary through a dry filter paper) into a dry roo cc 
Erlenmeyer flask. Pass a rapid current of dry air (pass through a 
CaCl, tower) into the mouth of the Erlenmeyer flask and heat ata 
temperature below 75° C. on a dry hot eins until the ether is 
entirely driven off. 

Note.—It is important to follow all of the details, since ether generally contains 
alcohol and after washing with water always contains water. It is very difficult 
to remove water and alcohol by evaporation from fatty acids, but the washing of the 
ether solution and subsequent drying with anhydrous sodium sulphate removes both 
water and alcohol. Ether, in the absence of water and alcohol, is easily removed 
from fatty acids by gentle heat. 

The fatty acids prepared as above should be kept in a stoppered 
flask and examined at once. 

(g) TEST FOR MINERAL O1,.—Place 10 drops of the fatty acid 
(f) in a 50 cc test tube, add 5 cc of alcoholic soda (see reagents), 
boil vigorously for five minutes, add 40 ce of water and mix. 
A clear solution indicates absence of more than a trace of unsaponi- 
fiable matter. If the solution is not clear, the oil is not pure 
linseed oil. : 

(h) IODINE NUMBER OF Fatry Acips.—Place a small quantity 
of the fatty acids (f) in a small weighing burette or beaker. Weigh 
accurately. Transfer by dropping about 0.15 g (0.10 to 0.20 g) 
to a 500 ce bottle having a well-ground glass stopper, or an 
Erlenmeyer flask having a specially flanged neck for the iodine 
test. Reweigh the burette or beaker and determine the amount 
of sample used. Add 10 ce of chloroform. Whirl the bottle 
to dissolve the sample. Add 10cc of chloroform to two empty 
bottles like that used for the sample. Add to each bottle 25 cc 
of the Hanus solution (see reagents) and let it stand with occa- 
sional shakings for one-half hour. Add 10 cc of the 15 per cent 
potassium-iodide solution and 100 cc of water, and titrate with 
standard sodium thiosulphate, using starch as indicator. The ti- 
tration on the two blank tests should agree within 0.1 cc. From 
the difference between the average of the blank titrations and 
the titration on the sample, and the iodine value of the thiosul- 
phate solution, calculate the iodine number of the sample tested. 
(Iodine number is centigrams of iodine to 1 g of sample.) If 


Specification jor Basic Carbonate White Lead, Dry and Paste 7 


the iodine number is less than 170, the oil does not meet the 
specification. 

(1) COARSE PARTICLES AND “SKINS.’’—Weigh an amount of 
paste containing 25 g of pigment (see 4 (d)), add 100 cc kero- 
sene, wash through a No. 325 screen and weigh the residue as in 
3 (c). 

5. REAGENTS. 


(a) EXTRACTION MrxTURE— 
, 10 volumes ether (ethyl ether). 
6 volumes benzol. 
4 volumes methyl alcohol. 
I volume acetone. 


(6) AguEous Soprum HyproxipE.—Dissolve 100 g sodium 
hydroxide in distilled water and dilute to 300 cc. 

(c) STANDARD SODIUM THIOSULPHATE SOLUTION.—Dissolve 
pure sodium thiosulphate in distilled water that has been well 
boiled to free it from carbon dioxide, in the proportion of 24.83 g 
crystallized sodium thiosulphate to 1,000 cc of the solution. 
It is best to let this solution stand for about two weeks before 
standardizing. Standardize with pure resublimed iodine.? This 
solution will be approximately decinormal, and it is best to leave 
it as it is after determining its exact iodine value, rather than to 
attempt to adjust it to exactly decinormal. Preserve in a stock 
bottle provided with a guard tube filled with soda lime. 

(d) StarcH SOLUTION.—Stir up 2 to 3 g of potato starch or 
5 g of soluble starch with 100 cc of 1 per cent salicylic acid 
solution, add 300 to 400 cc of boiling water, boil the mixture 
until the starch is practically dissolved, and then dilute to one 
liter. 

(e) Porasstum IopIDE SoLuTION.—Dissolve 150 g potassium 
iodide free from iodate in distilled water and dilute to 1,000 cc. 

() Hanus SoLution.—Dissolve 13.2 g iodine in 1,000 cc of 
glacial acetic acid, 99.5 per cent, which will not reduce chromic 
acid. Add enough bromine, about 3 cc to double the halogen 
content, which is determined by titration. The iodine may be 
dissolved by applying heat, but the solution should be cold when 
the bromine is added. 

(g) ALCOHOLIC SoDIUM-HYyDROXIDE SoLuTION.—Dissolve pure 
sodium hydroxide in 95 per cent ethyl alcohol in the proportion of 


2 See Treadwell-Hall Analytical Chemistry, II, 3d ed., p. 646. 


8 Circular of the Bureau of Standards 


about 22 g per 1,000 cc. Let the solution stand in a stoppered 
bottle. Decant the clear liquid into another bottle, and keep well 
stoppered. This solution should be colorless or only slightly 
yellow when used, and it will keep colorless longer if the alcohol is 
previously treated with NaOH (about 80 g to 1,000 cc), kept at 
about 50° C. for 15 days, and then distilled. 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 


5 CENTS PER COPY 
V 


WASHINGTON : GOVERNMENT PRINTING OFFICB : 1924 


eT 


DEPARTMENT OF COMMERCE. 
BUREAU OF STANDARDS. 


S. W. STRATTON, Director. 


CIRCULAR OF THE BUREAU OF STANDARDS. 
No. 85. 


[2d edition. Issued July 3, 1922.] 


UNITED STATES GOVERNMENT SPECIFICATION FOR 
BASIC SULPHATE WHITE LEAD, DRY AND PASTE. 


ee ee 


FEDERAL SPECIFICATIONS BOARD. 
STANDARD SPECIFICATION NO. 6. . 


This Specification was officially adopted by the Federal Specifications Board on 
February 3, 1922,.for the use of the Departments and Independent Estab- 
lishments of the Government in the purchase of materials covered by it. 


CONTENTS. 

Page 
Es iy as sc go's wicca na sce a3 a2 Oe a he «Ps nn oe ee vig be I 
reat eee, cee Pe pee, Soe OT AL? Qk 2B. aA NTIS 2 
gsauotatory examination ofdry nigtidnt |) ). ch cpyscjice fi iy a boy brews om gee 2 
4 Laboratory, examination of paste. 22). b: snips cas ete mite es ees 3 5 
SO. Se OS AE ay PERRY SEE eh aaa eae reer! 7 


1. GENERAL. 


Basic sulphate white lead may be ordered in the form of dry 
pigment or paste ground in linseed oil. Material shall be pur- 
chased by net weight. | 

(a) Dry Picment.—The pigment shall be the sublimed product 
prepared from lead sulphide ores, free from impurities and adul- 
terants, and shall meet the following requirements: 

Color—Color Strength —When specified shall be equal to that of 
a sample mutually agreed upon by buyer and seller. 


Minimum. | Maximum. 


Coarse particles: Per cent. | Percent. 
Retained on standard Nor325 Screen. cas ces egs go erey wis gor ees - carps ereinn|s owtog. wer ase 1.0 
Composition: 
PRIOR GR oe ke hyiiclh tek Suhre eRe a Rai Gaia De GoE Sils ole ie BeBe Aiplan MOE s 11.0 18.0 
Oe ef RS en eee ene ne gee Af Cam So mmnET een mR oc (re Peete 9.0 
PEEL SIIEICIOE, ANUCIICING TOINOIO, 0 ois eas octets: crease mekeparenticelesctoneste be 1.0 


The remainder shall be lead sulphate. 


104952°—24——1 


2 Circular of the Bureau of Standards 


(b) Pastes.—The paste shall be made by thoroughly grinding 
the dry pigment with pure raw or refined linseed oil. 

The paste as received shall not be caked in the container and 
shall break up readily in oil to form a smooth paint of brushing 
consistency. It. shall mix readily in all proportions without 
curdling with linseed oil, turpentine, or volatile mineral spirits 
or any combination of these substances. 

The paste shall consist of: 


Pigment ooo ooo ois. 0.0 2 0:50 van nian 9g W WclW/d 0°91 4:9 oo RINSING ln/e's a 6 lp aR ea ee 
Linseed otk. i fi 55 oi ec 0 05 oes cle dS alsin in wiiooa 0 Bbeieiaee bite W nth nny tere eee satan a 
Moisture.and other volatile matter. oc... .jn:cicw.sviarsin-o.ope osninpeapeigin.s aubiaebaee © © aig Aaa gee oer 
Coarse 1 aa and “‘skins” (total residue retained on No. 325 screen, based on | — 

PAP MMENE) oi. os ovis wip sigue vi evaiesn wbelpelacmin’y 01 n(eie!ovaryLavala: ply em mire w ne, 9 oy oiaimhanl a eens tatai ae 


NotE.—Deliveries will, in general, be sampled and tested by the following methods, but the purchaser 
teserves the right to use any additional available information to ascertain whether the waterial meets 


the specification. 
2. SAMPLING. : , 

It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1,000 packages shall be taken as 
representative of the whole. 

With the dry pigment, this package shall be opened by the 
inspector and a sample of not less than 5 pounds taken at random 
from the contents and sent to the laboratory for test. 

With the paste, whenever possible, an original unopened con- 
tainer shall be sent to the laboratory; and when this is for any 
reason not done, the inspector shall determine, by thorough test- 
ing with a paddle or spatula, whether. the material meets the 
requirement regarding not caking in the container. (See 4a.) 
After assuring himself that the paste is not caked in the container 
the inspector shall draw a sample of not less than 5 pounds of the 
thoroughly mixed paste, place it in a clean dry metal or glass con- 
tainer, which must be filled with the sample, closed with a tight 
cover, sealed, marked, and sent to the laboratory for test with =e 
inspector’s report on caking in container. 

When requested, a duplicate sample may be taken from ‘the 
same package and delivered to the seller, and the inspector may 
take a third sample to hold for test in case of dispute. 


z 


3. LABORATORY EXAMINATION OF DRY PIGMENT. _ 


(a) Coror.—Take 1 g of the sample, add 10 to 12 drops linseed 
oil, rub up on a stone slab or glass plate with a flat-bottomed glass 
or stone pestle or muller to a uniform smooth paste... Treat in 


a 
- 
ee ee a a 


Specification for Basic Sulphate White Lead, Dry and Paste 3 


a similar manner, 1 g of the standard basic sulphate white lead. | 
Spread the two pastes side by side on a glass microscope slide and 
compare the colors. If the sample is as white as or whiter than the 
“standard,” it passes this test. If the “standard”’ is whiter than 
the sample, the material does not meet the specification. 

(0) CoLOR STRENGTH.—Weigh accurately 0.01 g of lampblack,. 
place on a large glass plate or stone slab, add 5 drops of linseed oil 
and rub up with a flat-bottomed glass pestle or muller, then add 
exactly 10 g of the sample and 45 drops of linseed oil and grind 
with a circular motion of the muller 50 times; gather up with 
_asharp-edge spatula and grind out twice more in a like manner, 
giving the pestle a uniform pressure. ‘Treat another 0.01 g of the 
same lampblack in the same manner except that 10 g of standard 
basic sulphate white lead is used instead of the 10 g of the sample. 
Spread the two pastes side by side on a glass microscope slide and 
compare the colors. If the sample is as light as or lighter in color 
than the “standard,” it passes this test. If the ‘“‘standard’”’ is 
lighter in color than the sample, the material does not meet the 
specification. 

(c) COARSE PaRTICLES.“~—Dry in an oven at 105 to 110° C. a 
No. 325 screen, cool, and weigh accurately. Weigh 25 ¢ of the 
sample, dry at roo°C.; transfer to a mortar, add 100 cc kerosene, 
thoroughly mix by gentle pressure with a pestle to break up all 
lumps, wash with kerosene through the screen, breaking up all 
lumps but not grinding. After washing with kerosene until all 
but the particles too coarse to pass the screen have been washed 
through, wash ali kerosene from the screen with ether or petroleum 
ether, heat the screen for one hour at 105 to 110° C., cool, and 
weigh. 

(d) QUALITATIVE ANtAnwiis —Test for matter insoluble in 
adi ammonium acetate solution, for calcium, for carbonates, 
and for any other impurities suspected by the regular methods a5 
qualitative analysis. 

(e) MorstuRE.—Place 1 g of the sample in a tared, wide mouth, 
short weighing tube provided with a glass stopper. Heat with 
igh aie removed for two hours at a temperature between 105 and 
110° C. Insert stopper, cool, and weigh. Calculate loss in weight 
as moisture. 

1 For a general discussion of screen tests of pigments and data regarding many pigments on the market, 


see Circular No. 148 of the educational bureau, scientific section, Paint Manufacturers’ Association of the 
United States. 


4 Circular of the Bureau of Standards 


(7) INSOLUBLE ImpuURITY AND Tota, LEap.—In a 250 ce 
beaker, moisten 1 g of the pigment with a few drops of alcohol; 
add 50 cc of acid ammonium acetate solution. (See Reagents 
5a.), Heat to boiling and boil for 2 minutes. Decant through a 
filter paper, leaving any undecomposed matter in the beaker. To 
the residue in the beaker, add 50 ce of the acid ammonium acetate 
solution, heat to boiling, and boil for 2, minutes. Filter through 
the same paper and wash with hot water. If an appreciable 
residue remains, ignite and weigh as insoluble impurity. Unite 
the acid ammonium acetate solutions, heat to boiling, and add 
dropwise, with stirring, a slight excess (in total about 10 to 15 cc) 
of dichromate solution. (See Reagents. 5b.) Heat until the 
precipitate assumes an orange color, let settle, filter on a weighed 
Gooch crucible, wash by decantation with hot water until the 
washings are colorless, and finally transfer all of the precipitate 
to the crucible. Then wash with 10 cc of 95 per cent ethyl 
alcohol and finally with ro cc of ethyl ether. Dry at 110 to 120° 
C., cool, and weigh PbCrO,.. Calculate to PbO by pulp iving | 
by the factor 0.69. 

(9) Zinc OxIpE.—Weigh accurately about 1 g of the pigment, 
transfer to a 400 cc beaker, add 30 ce of HCl (1:2), boil for 2 or 
3 minutes, add 200 ce of water and a small piece of litmus paper, 
add NH,OH until slightly alkaline, render just acid with HCl, 
then add 3 cc of concentrated HCl, heat nearly to boiling, and 
titrate with standard potassium ferrocyanide as in standardizing — 
that solution. (See Reagents 5d.) Calculate total zine as ZnO. 

(h) LEAD SULPHATE.—Treat 0.5 g of the pigment in a 400 cc 
beaker with a few drops of alcohol, add 10 ce of bromine water, 
1occ of HCl (1:1), and 3 g of NH,Cl. Cover with a watch glass 
and heat on a steam bath for 5 minutes, add hot water to give a 
total volume of about 200 cc, boil for 5 minutes, filter to separate 
any insoluble matter (a pure pigment should be completely dis- 
solved), and wash thoroughly with hot water. (The insoluble 
matter may be ignited, weighed, and examined qualitatively.) — 
Neutralize the clear solution (original solution or filtrate from 
insoluble matter) in a covered beaker with dry Na,CO,;, add 2 g 
more of dry Na,CO,, and boil 10 to. 15 minutes. Wash off cover, 
let settle, filter, and wash with hot water. Redissolve the precipi- 
tate in HCl (1:1), reprecipitate with Na,CO, as above, filter, and 
wash thoroughly with hot water. Acidify the united filtrates 
with HCl, adding about 1 cc in excess. Boil to expel bromine, 


Sl eet re as icc 
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Specification jor Basic Sulphate White Lead, Dry and Paste 5 


and to the clear boiling solution add slowly with stirring 15 cc of 
barium chloride solution. (See Reagents 5e.) Let stand on 
steam bath for about one hour, filter on a weighed Gooch crucible, 


wash thoroughly with boiling water, dry, ignite, cool, and weigh 


as BaSO,. Calculate to PbSO,, using the factor 1.3. 
(4) CaLcuLaTions.—Calculate the percentage of PbSO, to PbO 


by multiplying by the factor 0.736:and subtract the result from 


the percentage of PbO found under (f); report the difference as 


PbO. Report ZnO found under (g) as percentage of ZnO. Mois- 


ture and insoluble matter are reported as such.’ 
4, LABORATORY EXAMINATION OF PASTE. 


(a) CAKING IN CONTAINER.—When an original package iS 


received in the laboratory it shall be weighed, opened, and stirred 


with a stiff spatula or paddle. The paste must be no more difficult 
to break up and show no more caking than a normal good grade of 
white lead paste. ‘The paste shall be finally thoroughly mixed, 
removed from the container, and the container wiped clean and 
weighed. This weight subtracted from the’ weight of the original 
package gives the net weight of the contents. A portion of the 
thoroughly mixed paste shall be placed in a clean container and 
the portions for the remaining tests promptly weighed out from it. 

(b) Mrxinc with LInsEED Om.—One hundred grams of the 


“4 paste shall be placed in a cup, and 3occ of linseed oil added slowly 


with careful stirring and mixing with a spatula or paddle. The 
resulting mixture must be smooth and of good brushing con- 
sistency. 

(c) MoIsTURE AND OTHER VOLATILE MATTER.—Weigh accu- 
rately from 3 to 5 g of the paste into a tared flat-bottomed dish, 
about 8 cm in diameter, spreading the paste over the bottom. 
Heat at 105 to 110° C. for three hours, cool and weigh. Calculate 
loss in weight as percentage of moisture and other volatile matter. 

(d) PERCENTAGE OF PIGMENT._-Weigh accurately about 15 g 
of the paste into a weighed centrifuge tube. Add 20 to 30 cc of 
“extraction mixture” (see Reagents), mix thoroughly with a glass 
rod, wash the rod with more of the extraction mixture, and add 
sufficient of the reagent to make a total of 60 cc in the tube. 
Place the tube in the container of a centrifuge, surround with water, 


2 A method given by Schaeffer, J., Ind. and Eng. Chem., 6, p. 200 (1914), based on calculation of compo- 
sition after determination of moisture, impurities, total lead, and total zinc oxide, issometimes used. This 
method requires very accurate determination of Pb and ZnO, since the errors of determination are multi- 
plied by approximately four in making the calculation to PbO and Pbsos. 


104952°—24——2 


6 Circular of the Bureau of Standards ~ 


and counterbalance the container of the opposite arm with a sim- 
ilar tube or a tube with water. Whirl at a moderate speed 
until well settled. Decant the clear supernatant liquid. Repeat 
the extraction twice with 40 ce of extraction mixture and once 
with 40 cc of ether. After drawing off the ether set the tube in 
a beaker of water at about 80°C. or on top of a warm oven for 10 
minutes, then in an oven at 105 to 1ro° C. for 2 hours, Cool, 
weigh, and calculate the percentage of pigment. 

(¢) EXAMINATION OF PicMENT.—Grind the pigment from (d) to 
a fine powder, pass through a No. 80 screen to remove any “skins,” 
preserve in a stoppered tube, and examine as under 3 (2), 3(6), 3(d), 
3 (7), 3(9), 3(2), and 3 (2), Laboratory Examination of Dry Pigment. 

(7) PREPARATION OF Farry Aciws.—To about 25 g of the paste 
in a porcelain casserole add 15 cc of aqueous sodium hydroxide 
(see Reagents), and 75 cc of ethyl alcohol, mix, and heat uncovered 
on a steam bath until saponification is complete (about 1 hour). 
Add 100 ce of water, boil, add sulphuric acid of ‘specific gravity 
1.2 (8 to 10 cc in excess), boil, stir, and transfer to a separatory 
funnel to which some water has been previously added. Draw 
off as much as possible of the acid aqueous layer and PbSO, 
precipitate, wash once with water, then add 50 cc of water and 
50 cc of ether. Shake very gently with a whirling motion to 
dissolve the fatty acids in the ether, but not violently, so as to 


avoid forming an emulsion. Draw off the aqueous layer and wash 


the ether layer with one 15 ce portion of water and then with 5 ec 
portions of water until free from sulphuric acid. Then draw off 
completely the water layer. Transfer the ether solution to a dry 
flask, add 25 to 50 g of anhydrous sodium sulphate. Stopper the 
flask and let stand with occasional shaking at a temperature below 
25° C. until the water is completely removed from the ether solu- 
tion, which will be shown by the solution becoming perfectly clear 
above the solid sodium sulphate. Decant this clear solution (if 
necessary through a dry filter paper) into a dry 100 ce Erlenmeyer 
flask. Pass a rapid current of dry air (pass through CaCl, tower) 
into the mouth of the Erlenmeyer flask and heat to a temperature 
below 75° C. on a dry hot plate until the ether is entirely driven 
off. The fatty acids prepared as above should be kept in a stop- 
pered flask and examined at once.* oer 
*Itis important to follow all of the details since ether generally contains alcohol and after washing 
with water always contains water. It is very difficult to remove water and alcohol by evaporation from 
fatty acids, but the washing of the ether solution and subsequent drying with anhydrous sodium sulphate 


removes both water and alcohol. Ether, in the absence of water and alcohol, is easily removed from fatty 
acids by gentle heat. 


Specification for Basic Sulphate White Lead, Dry and Paste 7 


(g) Test For MINERAL O1L.—Place 10 drops of the fatty acid 
(j) in a 50 cc test tube, add 5 cc of alcoholic soda (see Reagents), 
_ boil vigorously for 5 minutes, add 40 cc of water, and mix; a clear 
solution indicates that not more than traces of unsaponifiable 
matter are present. If the solution is not clear the oil is not pure 
linseed oil. | 

(h) IopIneE NuMBER oF Farry Acips.—Place a small quantity of 
the fatty acids (f) in a small weighing burette or beaker and weigh 
accurately. ‘Transfer by dropping about 0.15 g (0.10 to 0.20 g) 
to a 500 cc bottle having a well-ground glass stopper, or an Erlen- 
meyer flask having a specially flanged neck for the iodine test. 
Reweigh the burette or beaker and determine the amount of sample 
used. Add 1occ of chloroform and whirl the bottle to dissolve the 
sample. Add 10 cc of chloroform to each of two empty bottles like 
that used for the sample. Add to each bottle 25 cc of the Hanus 
solution (see Reagents 5k) and let stand with occasional shaking 
for one-half hour. Add ro ce of the 15 per cent potassium iodide 
solution and 100 ce of water, and titrate with standard sodium 
thiosulphate, using starch as indicator. ‘The titration on the two 
blank tests should agree within 0.1 cc. From the difference be- 
tween the average of the blank titrations and the titration on the 
sample and the iodine value of the thiosulphate solution, calculate 
the iodine number of the sample tested. (Iodine number is centi- 
grams of iodine to 1 gof sample.) If the iodine number is less than 
170, the oil does not meet the specification. 

(1) COARSE PARTICLES AND ‘“‘SKINS.’’—Weigh out an amount 
of paste containing 25 g of pigment (see d), add 100cc of kero- 
sene, wash through No. 325 screen, and weigh the residue as 
in 3 (c). 

ef 5. REAGENTS. 

(a) Acip AMMONIUM ACETATE SOLUTION.—Mix 150 cc of 80 
per cent acetic acid, 100 ce of water, and 95 cc of strong ammo- 
nium (specific gravity 0.90). : 

_ (6) DicHROMATE SoLUTION.—Dissolve 100 g sodium dichro- 
mate (Na,Cr,0,2H,O) or potassium dichromate (K,Cr,O,) in water 
and dilute to 1,000 cc. 

(c) URANYL INDICATOR FOR Zinc TITRATION.—A 5 per cent 
solution of uranyl nitrate in water or a 5 per cent solution of 
uranyl acetate in water made slightly acid with acetic acid. 

_ (d) StanpDaRD Potasstum FERROCYANIDE.—Dissolve 22 ¢ 
of the pure salt in water and dilute to 1,000 cc. To standardize, 


8 Circular of the Bureau of Standards 


transfer about 0.2 g (accurately weighed) of pure metallic zine or 
freshly ignited pure ZnO to a 400 cc\ beaker. Dissolve in to ec 
of HCland 20 cc of water. Drop in a small piece of litmus paper, 
add NH,OH until slightly alkaline, then add HCl until just acid 
and finally add 3 cc of strong HCl. Dilute to about 250 cc with 
hot water and heat nearly to boiling. Run in the ferrocyanide 
solution slowly from a burette with constant stirring until a drop 
tested on a white porcelain plate with a drop of the uranyl indica- 
tor shows a brown tinge after standing 1 minute. A blank should be 
run with the same amounts of reagents and water as in the stand- 
ardization. The amount of ferrocyanide solution required for 
the blank should be subtracted from the amounts used in stand- 
ardization and in titration of the sample. The standardization 
must be made under the same conditions of temperature, volume 
and acidity as obtain when the sample is titrated. 
(e:) Barrum CHLORIDE SoLuTION.—Dissolve 100 g of pure 
crystallized barium chloride in water and dilute to 1,000 ce. | 
(f) StanDARD SopruM THIOSULPHATE SOLUTION.— Dissolve pure 
sodium thiosulphate in distilled water that has been well boiled to 
free it from CO, in the proportion of 24.83 g of crystallized 
sodium thiosulphate to 1,000 cc of the solution. It is best to 
let this solution stand for about two weeks before standardiz- 
ing. Standardize with pure resublimed iodine. (See Treadwell- 
Hall, Analytical Chemistry, vol. 2, 3d ed., p. 646.) This solu- 
tion will be approximately decinormal, and it is best to leave it as 
it is after determining its exact iodine value, rather than to at- 
tempt to adjust it to exactly decinormal strength. Preserve in a 
stock bottle provided with a guard tube filled with soda lime. © 
(g) StarcH SOLUTION.—Stir up 2 to 3 g of potato starch or 5 
g of soluble starch with roo cc of 1 per cent salicylic acid solu- 
tion, add 300 to 400 cc of boiling water, and boil the mixture until 
the starch is practically dissolved; then dilute to 1 liter. 
(hk) Extraction MrxtuRE.—Mix ro volumes ether (ethyl ether), 
6 volumes benzol, 4 volumes methyl alcohol, and 1 volume acetone. 
(i) AquEous Soprum HyproxipE.—Dissolve 100 g of NaOH 
in distilled water and dilute to 300 cc. . | 
(7) Porassrum IoprpE SoLuTIoN.—Dissolve 150 g of potassium 
iodide free from iodate in distilled water and dilute to 1,000 Cc. 
(k) Hanus SoLuTion.—Dissolve 13.2 g of iodine in 1,000 cc 
of glacial acetic acid, 99.5 per cent, which will not reduce chromic 
acid. Add enough bromine to double the halogen content, de- 


ie. ita 


Specification jor Basic Sulphate White Lead, Dry and Paste 9 


termined by titration (3 cc of bromine is about the proper 
amount). The iodine may be dissolved by the aid of heat, but 
the solution should be cold when the bromine is added. 

(1) ALconoric Soprum MHyproxipE SoLuTion.—Dissolve 
pure sodium hydroxide in 95 per cent ethyl alcohol in the propor- 
tion of about 22 g per 1,000 cc. Let stand in a stoppered bottle. 
Decant the clear liquid into another bottle, and keep well stop- 
pered. This solution should be colorless or only slightly yellow 
when used; it will keep colorless longer if the alcohol is previously 
treated with NaOH (about 80 g to 1,000cc) kept at about SO on 
for 15 days, and then distilled. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. ©. 
. AT 
5 CENTS PER COPY 


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U. S. Gov’t 
Master 
Specification 


No. 7b 
DEPARTMENT OF COMMERCE 


BUREAU OF STANDARDS 


George K. Burgess, Director 


CIRCULAR OF THE BUREAU OF STANDARDS, No. 86 


[3d, ed. issued October 11, 1926] 


UNITED STATES GOVERNMENT MASTER SPECIFICATION 
FOR TURPENTINE (GUM SPIRITS OF TURPENTINE AND 
STEAM-DISTILLED WOOD TURPENTINE) 


FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 7b 
[Revised August 7, 1926] 
This specification was officially promulgated by the Federal Specifications 
‘Board on February 3, 1922, for the use of the departments and independent 


establishments of the Government in the purchase of turpentine (gum spirits 
of turpentine and steam-distilled wood turpentine). 


[The latest date on which the technical requirements of this revision shall become mandatory for all 
departments and independent establishments of the Government is November 7, 1926. They may be put 
into effect, however, at any earlier date, after promulgation.] 


CONTENTS 


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BR SETTLE cee pent laes eeuer gs mien are a ine 
CCE a eatin ah on pen pt cons a ead me = 
VI. Methods of inspection, tests, and basis of purchase____-__------- 


ee ee TI PGT os. in en ae en seh eps en wegen min 
VIII. Notes.7- 59-4 PSAs. A 2. MAY VSS CRA Beas oe 


I. GENERAL SPECIFICATIONS 


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There are no general specifications applicable to this specification. 


Hi. TYPES 


This specification applies to two types of turpentine or spirits of 
turpentine as follows: 

A. Gum spirits of turpentine, commonly known as gum spirits. 
This is the product distilled from the oleoresin exuding from living 


- pine trees. 


10413°—26—1 


2 CIRCULAR OF THE BUREAU OF STANDARDS 


B. Steam-distilled wood turpentine, which is distilled with steam 
from the oleoresin within the wood. 


Il. MATERIAL. 1 1 4 970 
No details specified. 
IV. GENERAL REQUIREMENTS 
There are’no general requirements applicable to this specification. 
V. DETAIL REQUIREMENTS | 


Gum. spirits of turpentine or steam-distilled dod turpentine, 
as specified in contract, shall be pure and shall conform to the follow- 

ing requirements: 

APPEARANCE.—Shall be Senet and. free Pe poten intel 
and water. | 

Cotor.—Shall be standard”? or better. — 

Opor.—Shall be mild, aromatic, and characteristic of the type of 
turpentine specified. If desired, shall conform to the odor oh, the 
sample agreed. upon. 3 sho Sex aiieebaliell 


ae 4 


ppb Bonsie geo | mum] mum 
- LL LT TY ~ - —_——_— é 
Specific gravity, 15.5/15.5° C...--- 2-22-22 sean ne ennesenecss sig oe eae eee 0. 875 0. 860 
Refractive index. (Ma) at'20° C. ._.025 12 hn eee ge aa ee ee ae 1. 478 1. 465 
Residue after polymerization with 38 N H2S0O4: . 
Volume (per cexit) ...----- --22---2- = Ln SSE Se oe ZAP ue eeaeesees 
Refractive index (Np) at 20° C _____..---.------- 2+ --- 5 =e on nn ns enn nn aa] nena seane= 1, 500 
(This residue shall be viscous and its color straw or darker.) i AE Aca 4 
Initial boiling point &f 760 mim’ preseure_2 2-4 Ste 160° C. T9" C..: 
. 90 


Distilling below 170° C. at 760 mm pressure eta CODE) ne op cx aceedtmmasode cesar uaa eee eae 


VI. METHODS OF INSPECTION, TESTS, AND BASIS OF 
PURCHASE 


Deliveries will, in ene be inspected and tested by the Lsbowing 
methods, but the purchaser reserves the right to use any additional avail- 
able information to ascertain whether the material meets the aplication. 


|. DETECTION AND REMOVAL OF SEPARATED WATER Taha 


Draw a portion by means: of a glass-or,metal;container with a 
removable stopper or top, or with a “thief,” from the lowest part 
of the container, or by opening the bottom valve! of' thé perfectly 
level tank car. If water is found to be present draw it all out, 
record the quantity, and deduct it from the total volume of Jiquid’ 


delivered. | 
2, SAMPLING rwollot es snitnsdnys 


The method of sampling given under (qa) should be used when- 
ever feasible. When method (a) is not applicable method (6), 
(c), or (d) is to be used, according to the special conditions that obtain. 


SPECIFICATION FOR TURPENTINE 3 


(a) Waite Loapine Tank Car orn Wun Fitting Containers 
FOR SHIPMENT.—Samples shall be drawn by the purchaser’s inspector 
at the discharge pipe where it enters the receiving vessel or vessels. 
The composite sample shall be not less than 5 gallons, and shall 
consist of small portions of not more than 1 quart each taken at 
regular intervals during the entire period of loading or filling. The 
composite sample thus obtained shall be thoroughly mixed, and from 
it three samples of not less than 1 quart each shall be placed in clean, 
dry, glass bottles or tin cans, which must be nearly filled with the 
sample and securely stoppered with new, clean corks or well-fitting 
covers or caps. These shall be sealed and distinctly labeled by the 
inspector; one shall be delivered to the buyer, one to the seller, and 
the third held for check in case of dispute. 

(6) From Loaprep TANK Car or OrHEr LarGcE VEsseu.—The com- 
posite sample taken shall be not less than 5 gallons, and shall consist 
of numerous small samples of not more than 1 quart each taken from 
the top, bottom, and intermediate points by means of a metal or glass 
container with removable stopper or top. This device, attached to 
a suitable pole, is lowered to the various desired depths, when the 
stopper or top is removed and the container allowed to fill. The 
sample thus obtained is handled as in (a). | 
~ (c) Barrets AND Drums.—Barrels and drums shail be sampled 
after gauging contents. Five per cent of the packages in any ship- 
ment or delivery shall be represented in the sample. ‘Thoroughly 
mix the contents of each barrel to be sampled by stirrmg with a 
clean rod and withdraw a portion from about the center by means 
of a “‘thief’”’ or other sampling device. The composite sample thus 
obtained shall be not less than 3 quarts, shall consist of equal portions 
of not less than one-half pint from each package sampled, and shall 
be handled as in (a). Should the inspector suspect adulteration, he 
shall draw the samples from the suspected packages. 

(2) Smatt ContTarINers, Cans, ETCc., OF 10 GALLONS or LEss.— 
These should be sampled, while filling, by method (a) whenever pos- 
sible; but in case this is impossible the composite sample taken shall be 
not less than 3 quarts. This shall be drawn from at least five pack- 
ages (from all when fewer), and in no case from less than 2 per cent 
of the packages. The composite sample thus taken shall be thor- 
oughly mixed and subdivided as in (a). 


3. LABORATORY EXAMINATION 


(a) APPEARANCE.—Examine to determine compliance with the 
specifications. 
— (6) Cotor.—Fill a 200 mm perfectly flat-bottomed colorimeter 
tube, graduated in millimeters, to a depth of from 40 to 50 mm with 


% 


4 CIRCULAR OF THE BUREAU OF STANDARDS 


the turpentine to be examined. Place the tube in a colorimeter and 
place on or under it a No. 2 yellow Lovibond glass. Over or under a 
second graduated tube in the colorimeter place a No. 1 yellow Lovi- 
bond glass and run in the same turpentine until the color matches as 
nearly as possible the color in the first tube. Read the difference in 
depth of the turpentine in the two tubes. If this difference is 50 
mm or more the turpentine is ‘‘standard”’ or better. | 

(c) Opor.—Determine by comparison with the agreed-upon sam- 
ple, which shall have been kept in the dark in completely filled, well- 
stoppered bottles and free from separated water. 

(d) Spuciric Graviry.—Determine at 15.5/15.5° C. by any con- 
venient method that is accurate within 2 points in the fourth decimal 
place. 

(e) Rerractive [Npex.—Determine refractive index at 20° C. 
with an accurate instrument. When the refractive index is deter- 
mined at any other temperature, the readings obtained shall be 
corrected to 20° C. by adding to or by subtracting from the actual 
reading 0.00045 for each degree centigrade that the temperature at 
which the determination was made is, respectively, above or below 
20°C. 

(f) DistrtLation.—Apparatus.'—Condenser.—The type of appa- 
ratus (see fig. 1) adopted by the American Society for Testing Mate- 
rials for the distillation of paint thinners other than turpentine, sub- 
stituting for the thermometer there described? an immersed ther- 
mometer such as is described below, is preferred. In case the A. S. 
T. M. distillation apparatus is not available, use an ordinary straight 
glass-tube condenser, about 22 inches long, with 16 inches in contact 
with the cooling water. The end of the condenser tube should be 
fitted with an adapter or should be bent down to a nearly vertical 
position, and the tip should be cut off or ground down at an acute 
angle. The tip should extend a short distance mto the receiving 
cylinder. eh SARA 

Flask.—Comparable results can be obtained only by using flasks 
of the same dimensions. The distilling flask used shall be the stand- 
ard Engler flask, as used for petroleum distillation, having the fol- 
lowing dimensions: Diameter of bulb, 6.5 cm; cylindrical neck, 15 
cm long, 1.6 cm internal diameter; side or vapor tube, 10 cm long, 
0.6 cm external diameter, attached to neck at an angle of 75°, so 
that when the flask contains its charge of 100 ce of oil the surface of 
the liquid shall be 9 cm below the bottom of the junction of the side 
tube and neck. , 

Support for flask.—Support the flask on a plate of asbestos 20 
cm in diameter, having an opening 4 cm in diameter in its center, 


i Figure 1. 
7A.S. T. M. Standards, p. 607; 1918. 


a ee 


SPECIFICATION FOR TURPENTINE - 5 


and heat with an open flame. Surround the flask and burner with 
_a Shield to prevent fluctuation in the temperature of the neck of 
the flask. Or, support the flask in a metal cup, 15 to 20 em in 
diameter, containing high-boiling mineral oil or glycerin and fitted 
with a concave cover having in the center. a circular opening 514 
to 6 cm in diameter. In all cases take the necessary precautions 
to prevent. fluctuation in temperature in the neck of the flask. 
Thermometer.—The thermometer used for turpentine distillation 
shall conform to the following specifications: 
_. It shall be graduated from 145° to at least 200° C. in 0.2° inter- 
vals... Thermometers graduated above 200° C. may be used, pro- 


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‘Fis. L —Dislitiation apparatus 


idea Ser, hi sect rwiitle tbe following. ane eee Length, 
-bottom: of thermometer to 175° mark, not more than 8 nor less than 
6.5 cm. Length, top of bulb. to 145° mark, not less than 1.5): cm. 
“Length, 145 to 175° mark, not more than 6 cm, 

.. The. thermometer shall be made of suitable Jeiduachaniciie nye 
and thoroughly annealed, so that the scale errors will not increase 
after continued heating. 

_ The thermometer shall be filled er the mereury with an. inert 
gas, with sufficient pressure above the mercury column to prevent 
breaking of the column. It shall have a reservoir at the top, so 
thatthe pressure will not become excessive. at the highest 
temperature. | 
10413°—26——2 


6 CIRCULAR OF THE BUREAU OF STANDARDS 


Every fifth graduation shall be longer than the intermediate 
ones, and the marks shall be numbered at each interval of 5°. The 
graduation marks shall be clear-cut and fine and the numbering 
clear-cut and distinct. 

The error at any point on the scale shall not exceed +0.5° C. 
when tested for total immersion of the mercury column. 

Receiving cylinder.—Collect the distillate in an accurately grad- 
uated 50 or 100 cc cylinder. The so-called normal or precision 
cylinder of 50 cc capacity, having an internal diameter of 1.5 em 
and graduated in 0.2 cc, is preferred. If a cylinder with larger 
inside diameter is used, a pasteboard cover with a hole for the con- 
denser tube should be placed over the top. 

Operation.—Place 100 cc of the turpentine and several small 
pieces of pumice (or glass) in the distilling flask, fit the thermom- 
eter so that the top of the mercury bulb is level with the bottom 
of the side tube and the 175° C. (347° F.) mark is below the cork. 
Place the flask in position on the asbestos board or oil bath and 
connect with the condenser. Apply the heat cautiously at first, 
and when distillation begins regulate the heat so that the turpentine 
distills at the rate of not less than 4 nor more than 5 cc per minute 
(approximately two drops per second). The initial boiling point 
is the thermometer reading at the instant when the first drop falls — 
from the end of the condenser. Discontinue distillation when the 
temperature reaches 170.0° C. (338° F.), or an equivalent thereof, 
depending on the atmospheric pressure, as outlined below; let the 
condenser drain and read the percentage distilled. 

The percentage distilled below successive selected temperatures 
and the temperature at which each successive 10 cc distills may 
also be determined if desired, making the necessary correction of 
the temperature for variations in atmospheric pressure. ~ 

Correction for variation in atmospheric pressure.—Since distillation 
results are comparable only when obtained under exactly the same 
pressure conditions, turpentine should be distilled at that pressure 
which, at room temperature, is equivalent to a pressure of 760 mm 
of mercury at 0° C. Whenever the barometric reading after correcting 
to 0° C. is other than 760 mm a correction must be made. Since 
alteration of the pressure in the distilling system requires rather 
complicated apparatus, it is simpler to alter the temperature observa- 
tion points to correspond to the prevailing pressure. 

To determine what the barometric reading at the brcwailind room 
temperature, or at the temperature of the barometer, would be at 
0° C., read the barometer and thermometer alongside when about 
to begin distillation. Refer to Table 1, page’7.. Under the column 
nearest the observed pressure reading, and on the line nearest the 
observed temperature of the barometer, will be found the correction 


SPECIFICATION FOR TURPENTINE 7 


which must be subtracted from the observed pressure reading to 
obtain the equivalent, or true, reading at 0° C. 

The distilling temperature of turpentine is affected plus (+) or 
minus (—) 0.057° C. for each millimeter variation of the barometer 
above or below the normal 760 mm at 0° ©. If the barometer 
reading after correcting to 0° C. is below 760 mm, the turpentine 
will distill at a slightly lower temperature than under normal pressure. 
Therefore, the temperature recorded at the beginning of distillation 
(and any others observed during the course of the distillation) 
must be corrected to get its equivalent at normal pressure. The 
final temperature observation point (170° C. of the specifications) 
must be altered accordingly to get its equivalent at the pressure 
(corrected to 0° C.) at which distillation is made. 

For example, if the barometer reading after correcting to 0° C. 
is 750 mm, the correction of the observed initial distilling temperature 
will be 0.057 X10=0.6° C., approximately. If the reading of the 
thermometer when the turpentine begins to distill is 155.6° C. the 
corrected initial distilling temperature will be 155.6° +0.6° = 156.2° C. 
Furthermore, the temperature observation point at end of distillation 
(170.0° C. at 760 mm) must be altered to the same extent. Since 
the turpentine is distilling 0.6° C. below what it would at normal 
pressure, distillation must be discontinued at 0.6° C. below the speci- 
fied limit of 170.0° C. to determine the percentage distilling below 
170.0° C. 


TABLE 1.—Correction to barometer reading ! 
{From circular F, instrument division, Weather Bureau, U. S. Department of Agriculture] 


Tem- Observed reading of barometer, in millimeters 
' pera- 
ture, 
°C 640 | 650 | 660 | 670 | 680 | 690 | 700 | 710 | 720 | 730 | 740 | 750 | 760 | 770 | 780 

15.0 | 1.56 | 1.59 | 1.61 | 1.64 | 1.66 | 1.69 | 1.71 | 1.74 | 1.76 | 1.78 | 1.81 | 1.83 | 1.86 | 1.88 | 1.91 
16.0 | 1.67 | 1.69 | 1.72 | 1.75 | 1.77 | 1.80 | 1.83 | 1.85 | 1.88 | 1.90 | 1.93 | 1.96 | 1.98 | 2.01 | 2.03 
17.0 | 1.77 | 1.80} 1.83 | 1.86 | 1.88 | 1.91 | 1.94 | 1.97] 1.99 | 2.02 | 2.05 | 2.08 | 2.10 | 2.13 | 2.16 
18.0 | 1.88 | 1.91 | 1.93 | 1.96 | 1.99 | 2.02 | 2.05 | 2.08 | 2.11 | 2.14 | 2.17 | 2.20 | 2.28 | 2.26 | 2.29 
19.0 | 1.98 | 2.01 | 2.04 | 2.07 | 2.10 | 2.13 | 2.17 | 2.20 | 2.23 | 2.26 | 2.29 | 2.32 | 2.35 | 2.38] 2.41 
20.0 } 2. 9° 2.12 | 2.15 | 2.18 | 2.21 | 2.25 | 2.28 | 2.31 | 2.34 | 2.38 | 2.41 | 2.44) 247/251) 2.54 
21.0 | 2,19 | 2.22 | 2.26 | 2.29 | 2.32 | 2.36 | 2.39 | 2.43 | 2.46 | 2.50 | 2.53 | 2.56 | 2.60 | 2.63 | 2.67 
22.0 | 2.29 | 2.33 | 2.36 | 2.40 | 2.43 | 2.47 | 2.51 | 2.54 | 2,58 | 2.61 | 2.65 | 2.69 | 2.72 | 2.76 | 2.79 
23.0 | 2.40 | 2.43 | 2.47 | 2.51 | 2.54 | 2.58 | 2.62 | 2.66./ 2.69 | 2.73 | 2.77 | 2.81 | 2.84 | 2.88 | 2.92 
24.0 | 2.50 | 2.54 | 2.58 | 2.62 | 2.66 | 2.69 |. 2.73 | 2.77 | 2.81 | 2.85 | 2.89 | 2.93 | 2.97 | 3.01 | 3.05 
25.0 | 2.60 | 2.64 | 2.68 | 2.72 | 2.77 | 2.81 | 2.85 | 2.89 | 2.93 | 2.97 | 3.01 | 3.05 | 3.09 | 3.13 | 3.17 
26.0 | 2.71 | 2.75 | 2.79 | 2.83 | 2.88 | 2.92 | 2.96 | 3.00 | 3.04 | 3.09 | 3.13 | 3.17 | 3.21 | 3.26 | 3.30 
27.0 | 2.81 | 2.85 | 2.90 | 2.94 | 2.99 | 3.03 | 3.07 | 3.12 | 3.16 | 3.20 | 3.25 | 3.29 | 3.34 | 3.38 | 3.42 

_ 28.0 | 2.91 | 2.96 | 3.00 | 3.05 | 3.10 | 3.14 | 3.19 | 3.23 | 3.28 | 3.32 | 3.37 | 3.41 | 3.46 | 3.51 | 3.55 

' 29.0 | 3.02 | 3.06 | 3.11 | 3.16 | 3.21 | 3.25 | 3.30 | 3.35 | 3.39 | 3.44 | 3.49 | 3.54 | 3.58 | 3.63 | 3.68 
30.0 | 3.12 | 3.17 | 3.22 | 3.27 | 3.32 | 3.36 | 3.41 | 3.46 | 3.51 | 3.56 | 3.61 | 3.66 | 3.71 | 3.75 | 3.80 
31.0 | 3.22 | 3.27 | 3.32 | 3.37 | 3.43 | 3.48 | 3.53 | 3.58 | 3.63 | 3.68 | 3.73 | 3.78 | 3.83 | 3.88 | 3.93 
32.0 | 3.33 | 3.38 | 3.43 | 3.48 | 3.54 | 3.59 | 3.64 | 3.69 | 3.74 | 3.79 | 3.85 | 3.90 | 3.95 | 4.00 | 4.05 
33.0 | 3.43 | 3.48 | 3.54 | 3.59 | 3.64 | 3.70 | 3.75 | 3.81 | 3.86 | 3.91 | 3.97 | 4.02 | 4.07 | 4.13 | 418 


1 These corrections apply to a mercurial barometer with brass scale. They can, however, be used for a 
mercurial barometer with glass scale, since the errors introduced thereby are negligible as applied to the 
work contemplated in this circular. For exact correction to be applied to such a barometer, see Smith- 
sonian Physical Tables, p. 119; 1914. An aneroid barometer should not be relied on. 


For barometer readings below 640 mm the correction can be interpolated, since the difference, at any 
particular temperature, for each 10 mm variation in barometer reading is practically constant. 


3 Landolt-Boérnstein Physikalisch-Chemische Tabellen, Ed. 4, Table 127, p. 435. 


8 CIRCULAR OF THE BUREAU OF STANDARDS 


If the barometer reading corrected to 0° C. is above 760 mm, 
subtract the temperature correction from the observed thermometer 
reading to determine the initial distilling point, and continue distilla- 
tion to 170.0° C. plus the correction to determine the perouninae 
distilling below 170.0° C. 

(g) PonyMERIZzATION.—Place 20 ce of 38 N (equivalent to 100. 92 
per cent H,SO,) sulphuric acid in a graduated narrow-necked Babcock 
flask, stopper, and place in ice water to cool. Add slowly, from a 
pipette, 5 cc of the turpentine to be exammed. Gradually mix the 
contents, keeping warm, but being very careful that the temperature 
does not rise above 60° C. When the mixture no longer warms up on 
shaking, agitate thoroughly and place the flask in a water bath and 
heat at 60 to 65° C. for not less than 10 minutes, keeping the contents 
of the flask thoroughly mixed by vigorous shaking for one-half 
minute each time, six times during the period. Do not stopper the 
flask after the turpentine has been added, as itmay explode. Cool to 
room temperature, fill the flask with concentrated sulphuric ‘acid 
until the unpolymerized oil rises into the eraduated neck and centri- 
fuge from 4 to 5 minutes at not less than’1,200 r. p. 'm., or’ for’ 15 
“minutes at 900 r. p. m., or allow to stand, lightly stoppered, ‘for 12 
hours. Calculate the pettGhithee? note the consistency’ and’ color, 
and determine the refractive index (at 20° C. ) of tite unpolymerized 
residue. 

Reagent for testing.—In a weighed, glass-stoppered bottle (the 
regular 214-liter acid bottle is of a convenient size) mix ordinary 
concentrated sulphuric acid (sp. gr. 1.84) with fuming sulphuric acid. 
If the fuming acid used contains 50 per cent excess SO;, the’ ratio 
of one part, by weight, of the former. to three-fourths of apart; by 
weight, of the latter will give a mixture slightly stronger than the 
required strength. To determine the exact strength of this mixture 
in terms of H,SO,, weigh exactly, in a weigh toes pipette of about 
10 ce capacity, approximately 20 g of the acid. ° ‘ Allow it to flow down 
the sides of the neck into a'1,000 cc volumetric flask contaming about 
200 ce of distilled water. When the pipette has drained, wash all 
traces of the acid remaining in the pipette into the’ flask, taking 
precautions to prevent loss of SO;, and make up to the mark. -Titrate 
20 ce portions, drawn from a burette, against half normal | alkali. 
Calculate the concentration in terms of the aria et hig iSO, 
in the sample taken. 

In the same way determine the percentage of HS, i in aN stock of 
ordinary concentrated acid (sp. gr. 1.84). From these data calculate 
the quantity of the latter which must be added to the quantity of 
mixed acid in the weighed bottle to bring it to a a 
terms of H,SOQO,, of 100.92. per cent. 2 alee : 


SPECIFICATION FOR TURPENTINE 9 


4 After adjusting the concentration by the addition of the ordinary 
sulphuric acid, thoroughly shake the bottle of mixed acid and again 
determine its concentration. The allowable variation is +0.05 per 


» cent H,SO, Finally, as a check run a polymerization test on gum 
turpentine known to be pure. The residue should fall below 2 per 
cent. 


Special precautions must be taken to piey eat dilution of this acid. 
by the absorption of atmospheric moisture. The arrangement shown 
in Figure 2 is most suitable for storing 
and delivering measured quantities of 
this reagent. 

With the three-way stopcocks A and 
B in the position shown, acid is siphoned 
into the pipette P, the displaced air 
passing into &. To empty the pipette, 
A and B are turned to the position 
shown by the broken lines, air passing 
in ata. The acid adhering to the walls 
of the pipette dries this air so that when 
it passes into R on again filling the 
pipette there is no accumulation of 
moisture in the acid remaining in the 
reservoir. If such arrangement is not to 
be had, the acid should be kept in well- 
fitting glass-stoppered bottles of not more 
than one-half liter capacity. 


Nts a aes MN PLM PRUE MRE MIME Tey Mater) Se AE Tae PUG, ON MEMS, oe MMR UeY ee et AAS 
Daedlhah  oe nei | ie ial — ees ome i ag abe ae oe ‘ ? = oe ee + r . y 7 


Fa ands 
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4. BASIS OF PURCHASE 


(a) Unrr.—Turpentine shall be pur- 
: chased (a) by volume, the unit being a 
* gallon of 231 cubic inches at 15.5° C. 
4 (60° F.), or (6) by weight. A gallon of 
turpentine at 15.5° C. (60° F.) weighs 
7.19 to 7.30 pounds. The exact weight 
in pounds per gallon of any sample can Fig. 2.—Acid bottle and pipetie 

be determined by multiplying the specific 

gravity at 15.5/15.5° C. (60/60° F.) by 8.33. Example: If the specific 
gravity at 15.5° C. is 0.8642, the weight per gallon at this tempera- 
ture will be 0.8642 X 8.33 =7.199 pounds. 

When purchased by weight, quotations shall be by the pound or 
by the 100 pounds. The request for bids will state whether quota- 
tions shall be by the gallon, pound, or 100 pounds. 

(6) Correction or VoLtumME.—The gallonage paid for shall be the 
volume corrected to a standard temperature of 15.5° C. (60° F.). 


ee, 


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phn ete 
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10 CIRCULAR OF THE BUREAU OF STANDARDS 


The correction shall be deducted from (when the temperature of 
gauging is above 15.5° C.) or added to (when the temperature of 
gauging is below 15.5° C.) the gallonage as gauged. Such deduction 
or addition shall be computed on the basis of a coefficient of expan- 
sion for turpentine of 0.000945 per degree centigrade (or 0.000525 
per degree Fahrenheit). -Example: If the temperature at which the 
turpentine is gauged is 75° F. and the volume delivered (at that 
temperature) is 8,000 gallons, then 0.000525 x 15° 8,000 gallons 
equals the quantity in gallons which must be subtracted from 8,000 
gallons to give the true gallonage at 60° F., or if the temperature at 
which the turpentine is gauged is 10° C., then 0.000945 x 5.5° X 8,000 
gallons equals the quantity in gallons which must be added to the 
gauged volume of 8,000 gallons to give the true gallonage at 15.5° O. 

(c) Certirication.—Turpentine delivered in. barrels, drums, or 
tank cars shall either be accompanied by an official gauger’s certifi- 
cate showing the net contents of each container and also the tem- 
perature of contents at time of gauging, or shall be subject to gauging 
by the purchaser’s inspector. In the absence of a statement of the 
temperature at the time of gauging on the official gauger’s certifi- 
cate, or in case the barrels show evidence of loss by leakage or other 
shortage, the delivery shall be subject to Beco and | Tegauging 
by the purchaser’s. inspector. 


VII. PACKING AND MARKING 


Packing shall be in accordance with commercial practice, unless 
otherwise specified. | 
VIII. NOTES 


This sphcification does not cover what is norm as destructively 
distilled wood turpentine. | 


ADDITIONAL OOPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 


& CENTS PER COPY 
V 


Seeeat. * 


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DEPARTMENT OF COMMERCE. 


BUREAU OF STANDARDS. 


S. W. STRATTON, Director. 


CIRCULAR OF THE BUREAU OF STANDARDS. 
No. 87. 


[2d edition. Issued July 3, 1922.] 


UNITED STATES GOVERNMENT SPECIFICATION FOR 
ZINC OXIDE, DRY AND PASTE. 


FEDERAL SPECIFICATIONS BOARD. 
STANDARD SPECIFICATION No. 8. 


This Specification was officially adopted by the Federal Specifications Board on 
February 3, 1922, for the use of the Departments and Independent Establish- 
ments of the Government in the purchase of materials covered by it. 


CONTENTS. 
Page 
Aa a ie be Te Maar ae SiO rr oe ete ae aie cn OE ater hs Petes I 
TREN 00g Ce eras iis otle vw ls nicks s DLs « he hale Bale: oo Oe eee ae 2 
3. Laboratory examination of dry pigment... ....... 0... c eee eee eee beens 3 
A iavorsiory examination of paste. .°... 2.0)... mi eieiug «myels ey veers deere 4 
i ee een tsk oa a 0G Bees he tk ng se oOo es «x Se od 7 


1. GENERAL. 


: Zinc oxide may be ordered in the form of dry pigment or paste 


ground in linseed oil. Purchases shall be made on the basis of 
net weight. 

The pigment may be American process zinc oxide, made direct 
from the ore, or French process zinc oxide, made from spelter. 
The contract shall state which kind is desired. 

The color and color strength when specified shall be equal to 


samples mutually agreed upon by buyer and seller. 


109842°—22 


2 Circular of the Bureau of Standards 


The pigment shall meet the following requirements: 


Maximum.|! Minimum. 


’ Per cent. | Per cent. 
Coarse particles retained on Standard No. 325 SCreeM...............seseeeerenes Li MD ick eee 


Amerlcan process. _ French process. 


Maximum.| Minimum. | Maximum.| Minimum, 


Per cent. | Percent. | Percent. | Per cent. 


PAO NORIO 25 5 5h os Sls ook os Sma oh ee ok ee ee om a een aa ene bo ae eee a 
PP otal ALOR oe fscxs heer ks yee 5 Pass Aes uae ite tae OZ cea Out aes caiman ta 
Total impurities, including moistute=. uc). 174 STs 2D, sot ay SEER , 1s To oy hee 


The paste shall be made by thoroughly grinding the above 
pigment with pure raw or refined linseed oil. The paste shall 
not cake in the container and shall break up readily in cu to 
form a smooth paint of brushing ogee * ae te 

The paste shall consist of: 


: ‘Maximum. Minimum, 


Pigment. 00.26.85. eyed ee emeg ees cine cree Leahey — ee oye temntiice 
TinSCOG, Cll... uss cc ws tis a etks div ns bts ok ase ele athe’ wictrolw ave 2Scaw shes (ay ole ecieain aine en ne 
Coarse particles. and ‘‘skins”’ (total residue leit on No. 325 screen based, on pigitent) Ot 


Woisture and other volatile miatter. ee TA. Tce nec e nae s cee ne emen ae ee |S hem 


Norte.—Deliveries will, in general, be sampled and tested by the following methods, but the ‘sia 
reserves the right to use any additional available information to ascertain whether the material meets the 
specification. 


2. SAMPLING. 


- It is mutually agreed by buyer and seller that a single package 
out of each lot of not. more than 1,000 packages shall be taken as 
representative of the whole. AICTE 

With the dry pigment, this package is to be opened by ees in- 
spector and a sample of not less than 5 pounds taken at random 
from the contents and sent to the laboratory for test. When 
requested, a duplicate sample may be taken from the same pack- 
age and delivered to the seller, and the inspector sh take a cod 
sample to hold for test. in case of dispute. ihe 

With the paste, whenever possible, an original nope Re 
tainer shall be sent to the laboratory; and when this is for any 
Treason not done, the inspector shall determine by thoroughly’ test- 

ing with a paddle or spatula whether the material meets the 
requirement regarding not caking in the container. (See 4 “(a).) 
After assuring himself that the paste is not caked ii tHe — ‘the 


ee eae eae eer a eee gOS ee 
bagi » * > o_o. 


Specification for Zinc Oxide, Dry and Paste 3 


inspector jshall draw a sample of not Jess than 5 pounds of the 
thoroughly mixed paste, place it in a clean, dry metal or glass 
container which must be filled with the sample, closed with a tight 
cover, sealed, marked, and sent to the laboratory for test with the 
imspector’s report on caking in container. 


3. LABORATORY EXAMINATION OF DRY PIGMENT. 


(a) Coror.—Take 5 ¢ of the sample, add 1.5 cc of linseed oil, 


tub up on a stone slab or glass plate with a flat-bottomed glass or 
“stone pestle or muller to a uniform smooth paste. ‘Treat in ‘a 


similar manner 5 g of the standard zinc oxide. Spread the two 
pastes side by side on a clear colorless glass plate and compare the 


colors. Ifthe sample is as white as or whiter than the “‘ standard,” 
it passes this test. If the ‘‘standard”’ is whiter than the sample, 


the material does not meet the specification. 
(6) Color STRENGTH.—Weigh accurately 0.01 ¢ of lampblack, 


place on a large glass plate or stone slab, add o.2 cc of linseed oil 


and rub up with a flat-bottomed glass pestle or muller, than add 
exactly 10 g of the sample and 2.5 cc of linseed oil, and grind with 
a circular motion of the muller 50 times; gather up with a sharp- 
edged spatula and grind owt twice more in a like manner, giving 
the pestle a uniform pressure. ‘Treat another 0.01 g of the same 
lampblack in the same manner except. that 1o g of standard zinc 
oxide is used instead of the 10 g of the sample. Spread the two 


pastes side by side on a glass microscope slide and compare the 


colors. If the sample is as light as or lighter in color than the 
“standard,” it passes this test. If the “standard” is lighter in 
color than the sample, the material does not meet the specification. 

(c) COARSE PARTICLES..—Dry in an oven at 105 to 110° C. a 
325 screen, cool and weigh accurately. Weigh 10 g of the sample; 
dry at 100° C., transfer to a mortar, add 100 cc kerosene, thor- 


oughly mix by gentle pressure with a pestle to break up all lumps, 
‘wash with kerosene through the screen, breaking up all lumps, 


but not grinding. After washing with kerosene until all but the 
particles which are too coarse to pass the screen have been washed 
through, wash all kerosene from the screen with ether or petro- 


leum ether, heat the screen for one hour at 105 to 110° C., cool and 


weigh. | 


1 For a general discussion of screen tests of pigments and data regarding many pigments on the market, 


‘see Circular No. 148 of the Educational Bureau, Scientific Section, Paint Manufacturers’ Association of 
the United States. 


4 Circular of the Bureau of Standards 


(d) QUALITATIVE ANALYsIS.—Test for matter insoluble in hy- 
drochlorie acid, for lead, calcium, etc., by regular sic i of 
qualitative analysis. 

(e) Zinc OxipE.—With samples free from iiptaritiel ca (d)), 
ignite a weighed sample and calculate the residue as ZnO. With 
samples containing impurity, proceed as follows: Weigh accu- . 
rately about 0.25 g, transfer to a 400 cc beaker, moisten with 
alcohol, dissolve in 10 cc of hydrochloric acid and 20cc of water 
and titrate with standard potassium ferrocyanide, following the 
procedure used in standardizing this reagent. _ (See 5(2).) 

(7) Tora, SuLPpHUR,—Weigh accurately about 10 g of the 
sample. Moisten with afew drops of alcohol, add 5 ce of bromine 
water (saturated solution of bromine), then concentrated hydro- 
chloric acid in excess, boil to expel bromine, and dilute to about 
roo cc. (Material complying with the specification should all go 
into solution; if insoluble matter remains, filter and examine by 
appropriate methods.) Make alkaline with ammonia, then just 
acid with hydrochloric acid, heat to boiling and add about 10 cc 
of hot barium chloride solution. (See Reagents.) Let stand 
several hours (overnight), filter on a weighed Gooch crucible, 
wash thoroughly with hot water, dry, ignite, cool, and nests the 
BaSO,. Calculate to S (BaSO, x 0.1373 =S). ae 


4. LABORATORY EXAMINATION OF PASTE. 


(2) CAKING IN CONTAINER.—When an original package is re- 
ceived in the laboratory, it shall be weighed, opened, and stirred 
with a stiff spatula or paddle. The paste must be no more difficult . 
to break up and show no more caking than a normal good grade 
of zinc oxide paste. The paste shall be finally thoroughly mixed, 
removed from the container, the container wiped clean, and 
weighed, This weight subtracted from the weight of the original 
package gives the net weight of the contents. A portion of the 
thoroughly mixed paste shall be placed in a clean container and 
the portions for the remaining tests promptly weighed out. 

(0) Mrxinc witH LINSEED Or.—One hundred grams of eid 
paste shall be placed in a cup, 35 cc of linseed oil added slowly 
with careful stirring and mixing with a spatula or paddle. The 
resulting mixture must be smooth and of good beasts con- 
sistency. 

(c) MoIstTURE AND OTHER VOLATILE MATTER. te accu- 
rately from 3 to 5 g of the paste into a tared flat-bottomed dish, 
about 8 cm in diameter, spreading the paste over the bottom. 


RIS 


et tt ca aie eae Sick co Se ade aa 


Specification for Zinc Oxide, Dry and Paste 5 


Heat at 105 to 110° C. for three hours, cool, and weigh. Calculate 
loss in weight as percentage moisture and other volatile matter. 

(d) Per Cent PicmMent.—Weigh accurately about 15 g of the 
paste into a weighed centrifuge tube. Add 20 to 30 cc of “ex- 
traction mixture’? (see Reagents), mix thoroughly with a glass 
rod, wash the rod with more of the extraction mixture, and add > 
sufficient of the reagent to make a total of 60 cc in the tube. 
Place the tube in the container of a centrifuge, surround with 
water, and counterbalance the container of the opposite arm with 
a similar tube or a tube with water. Whirl at a moderate speed 
until clear. Decant the clear supernatant liquid. Repeat the 
extraction twice with 40 cc portions of extraction mixture, and 
once with 40 cc of ether. After drawing off the ether, set the 
tube in a beaker of water at about 80° C. or on top of a warm 
oven for 10 minutes, then in an oven at 105 to 110° C. for 2 hours. 
Cool, weigh, and calculate percentage of pigment. 

(ec) EXAMINATION OF PiGMENT.—Grind the pigment from (d) 
to a fine powder, pass through a No. 80 screen to remove any 
‘‘skins,”’ preserve in a stoppered tube and apply tests 3 (d), (¢), 
and (f). If required, apply tests 3 (a) and (b) in.comparison with 
a portion of pigment extracted from the standard paste in enaehy 
the same manner as in extracting the sample. 

_(f) PREPARATION OF Farry Acips.—To about 25 g of the paste 
in a porcelain casserole add 15 cc aqueous sodium hydroxide (see 
Reagents), and 75 cc of ethyl alcohol, mix and heat uncovered on 
a steam bath until saponification is complete (about one hour). 
Add. 100. ce water, boil, add sulphuric acid of specific gravity 
1.2 (8 to 10 cc in excess), boil, stir, and transfer to a separatory 
funnel to which some water has been previously added. Draw 
off as much as possible of the acid aqueous layer, wash once 
with water; then add 50 cc of water and 50 cc of ether. Shake 
very gently with a whirling motion to) dissolve the fatty acids 
in the ether, but not violently, so as to avoid forming an 
emulsion. Draw off the aqueous layer and wash the ether layer 
with one 15 cc portion of water and then with 5 cc portions of 
water until free from sulphuric acid. Then draw off completely 
the water layer. Transfer the ether solution to a dry flask, and 
add 25 to 50g of anhydrous sodium sulphate. Stopper the flask 
and let, stand with occasional shaking at a, temperature below 25° 
C. until,the water is completely removed from the ether solution, 
which will be shown by the solution becoming perfectly clear 


6 Circular of the Bureau of Standards» 


above the solid sodium sulphate. Decant this clear solution (i 
necessary through a dry filter paper) into a dry 100 ce’ Erlenmeyer 
flask. Passa rapid current of dry air (pass through CaCl, tower) 
into the mouth of the Erlenmeyer flask and heat to a temperature 
below 75°C. on a dry hot plate until the either is entirely driven off. 

Norte.—It is important to follow all of the details, since ether generally contains 
alcohol and after washing with water always contains water. It is very difficult 
to remove water and alcohol by evaporation from fatty acids, but.the washing of the 
ether solution and subsequent drying with anhydrous sodium sulphate removes both 


water and alcohol. Ether, in the absence of water and alcohol, is aoa removed 
from fatty acids by gentle heat. 


The fatty acids prepared as above should ba kept ina stoppeted 
flask and examined at once. 

(g) TEST FoR MINERAL Ol AND OTHER Unkasonnaialien ie 
TER.—Place ro drops of the fatty acid’ (f) in a 50 ¢e test tube, 
add 5 cc of alcoholic soda (see Reagents); boil vigorously for 5 
minutes, add 40 ce of water, and mix; a clear solution indicates 
that not more than traces of unsaponifiable matter are present. 
If the solution is not clear, the oil is not pure linséed oil. 

(h) IoprIne NuMBER oF Farry Actps.—Place’a small quantity 
of the fatty acids (f) in a small weighing burette or beaker. 
Weigh accurately. Transfer by dropping about 0:15 g (0.10 to 
0.20 g) toa 500 cc bottle having a well-ground glass stopper, or 
an Erlenmeyer flask having a specially flanged neck for the iodine 
test. Reweigh the burette or beaker and determine the amount 
of sample used. Add 10 cc of chloroform. Whirl the bottle to 
dissolve the sample. Add 10 cc of chloroform to two empty 
bottles like that used for the sample. Add to each bottle 25 cc of 
the Hanus solution (see Reagents) and let stand, with occasional 
shaking, for one-half hour. Add 10 ce of thé 15 per cent potas- 
stum-iodide solution and 100 cc of water, and titrate with standard 
sodium thiosulphate, using starch as indicator. The titrations on 
the two blank tests should agree within 0.1 cc. ' From the differ- 
ence between the average of the blank titrations and the titration 
on-the sample and the iodine value of the thiosulphate solution, 
calculate the iodine number of the sample tested. (Iodine 
number is centigrams of iodine to 1 g of sample.) If the iodine 
number is less than 170, the oil does not meet the specification. 

(7) CoaRSE PARTICLES AND ‘‘SKINS.”—Weigh an”amount of 
paste containing 10 g of pigment (see 4 (d)), add kerosene, and 
wash through a No. 325 screen asin 3 (c). The residue is reported 
as ‘“Coarse particles and skins.” : : 2 tal aw 


PREG Oe eh See eC EE EME IETS nyt FE Eee S| SERIE en ee 


Spectfication for Zinc Oxide, Dry and Paste y 
5. REAGENTS. 


(a) EXTRACTION MIxTURE.— 

- 10 volumes ether (ethyl ether). 
6 volumes benzol. 
4 volumes methyl]! alcohol. 
I volume acetone. 

(6) AguEous Sopium HyproxipE.—Dissolve 100 g sodium 
hydroxide in distilled water and dilute to 300 cc. 

(c) STANDARD SopiumM ‘THIOSULPHATE SOLUTION.—Dissolve 
pure sodium thiosulphate in distilled water that has been well 
boiled to free it from carbon dioxide, in the proportion of 24.83 g 
crystallized soditim thiosulphate to 1,000 cc of the solution. It is 
best to let this solution stand for about two weeks before stand- 
ardizing. Standardize with pure resublimed iodine. (See Ana- 
lytical Chemistry, Treadwell-Hall, vol. 11, 3d ed., p. 646.) This 
solution will be approximately decinormal, and it is best to leave 
it as it is after determining its exact iodine value rather than to 
attempt to adjust it to exactly decinormal. Preserve in a stock 
bottle provided with a guard tube filled with soda lime. 

(dy SvarCu SoLution.—Stir up 2 to 3 g of potato starch or 
5 g soluble Starch with too cc of'1 per cent salicylic acid solution, 
add- 300 to 400 cc boiling water, and boil the mixture until the 
starch is practically dissolved, then dilute to 1 liter. 

(e) Potassium IopIpDE SoLuTION.—Dissolve 150 g of potassium 
iodide free from iodate in distilled water and dilute to 1,000 cc. 

(f) Hanus SoLutTIon.—Dissolve 13.2 g of iodine in 1,000 ce 
of 99.5 per cent glacial acetic acid which will not reduce chromic 
acid. Add enough bromine to double the halogen content, 
determined by titration (3 cc of bromine is about the proper 
amount). The iodine may be dissolved by the aid of heat, but 
the solution should be cold when the bromine is added. 

(g) ALCOHOLIC SoDIUM HYDROXIDE SOLUTION.—Dissolve pure 
sodium hydroxide in 95 per cent ethyl alcohol in the proportion 
of about 22 g per 1,000 cc. Let stand in a stoppered bottle. 
Decant the clear liquid into another bottle and keep weil stop- 
pered. ‘This solution should be colorless or only slightly yellow 
when used, and it will keep colorless longer if the alcohol is pre- 
viously treated with sodium hydroxide (about 80 g to 1,000 cc), 
kept at about 50° C. for 15 days and then distilled. 


8 Circular of the Bureau of Standards 


(h) URANYL INDICATOR FOR Zinc TiTRaTION.—A 5 per cent 
solution of uranyl nitrate in water or a 5 per.cent. solution, of 
uranyl acetate in water made slightly acid; with acetic acid. 

(2) STANDARD PoTassIuM FERROCYANIDE.—Dissolve 22 g of 
the pure salt in water and dilute to 1,000 cc. To standardize 
transfer about 0.2 g (accurately weighed) of pure metallic zinc 
or freshly ignited pure zinc oxide to a 400 cc beaker. Dissolve in 
10 cc hydrochloric acid and 20 ce water... Drop in a :small piece 
of litmus paper, add ammonium hydroxide until slightly alkaline, 
then add hydrochloric acid until just acid, and then add 3 cc 
strong hydrochloric acid. Dilute to about 250 cc with hot water 
and heat nearly to boiling. Run in the ferrocyanide solution 
slowly from a burette with constant stirring until a drop tested 
on a white porcelain plate with a drop of the uranyl indicator 
shows a brown tinge after standing one minute. A blank should 
be run with the same amounts of reagents and water as in the 
standardization. The amount of ferrocyanide solution required 
for the blank should be subtracted from the amounts used in 
standardization and in titration of the sample. The standardiza- 
tion must be made under the same conditions of temperature, 
volume, and acidity as obtain when the sample is titrated, _ 

(7) Bartum CHLORIDE SOLUTION.—Dissolve 100 g of pure crys- 
tallized barium chloride in water and dilute to 1,000 cc. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
HE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 

5 CENTS PER COPY ; ; L f4) 
v ort ampngsl 


WASHINGTON : GOVERNMENT PRINTING OFFICE : fo22 


a ee 


oe RT, Se Rr aC I aD 


See A eT ee Le eT oe Ta RS. ery IS Oe Pe a 


et: 4 
od 


DEPARTMENT OF COMMERCE. 
BUREAU OF STANDARDS. 


S. W. STRATTON, Director. 


CIRCULAR OF THE BUREAU OF STANDARDS. 


No. 88. 


[2d edition. Issued July 3, 1922.] 


UNITED STATES GOVERNMENT SPECIFICATION F OR 
LEADED ZINC OXIDE, DRY AND PASTE. 


FEDERAL SPECIFICATIONS BOARD. 
STANDARD SPECIFICATION NO. 9. 


This Specification was officially adopted by the Federal Specifications Board on 
February 3, 1922, for the use of the Departments and Independent Fstablish- 


ments of the Government in the purchase of materials covered by it. 


CONTENTS. 

Page, 
ag ED a lab ten ai olay en As Ya eae I 
MME CR Riayat 2) oe Akay Jk ve Soeut,. tk Se Reps 2 
3- Laboratory examination of mig cht tah ae Sa ee Rem cate» i, Ae optic NR Sie 3 
ee -Leboratory examination of paste. 2.6 U0. 2 JOR. I Jo) Ae 4 
RE oi yas ao, nee s's a a PalghQalos AEE. Bh sshd whee 7 

1. GENERAL. 


Leaded zine oxide, frequently known as leaded zinc, consists 
of zinc oxide and varying amounts of lead compounds. It may 
be ordered in the form of dry pigment or paste ground in linseed 
oil. Purchases shall be made on the basis of net weight. 

The pigment may be high-leaded zinc oxide or low-leaded zinc 
oxide. The contract shall state which kind is desired. The color 
and color strength when specified shall be equal to samples mutu- 
ally agreed upon by buyer and seller. 


106489°—24 


2 Circular of the Bureau of Standards 


The pigment shall meet the following requirements: 


Maximum.) Minimum, 


Per cent. | Percent. 
Coarse particles retained on Standard No. 325 screen .........--.-----+-+---++++-- LO hice kee ey 


High-leaded. Low-leaded. 


Maximum. | Minimum. | Maximum. | Minimum. 


| ee | 


Percent. | Percent. | Percent. | Per sage 


Zinc oride (ZnO) .. noes eB Ge sed be Saeco Sn ers «<a Te es eee 
Water soluble salts: -..25c. so 28s ee st ackk caeaerenens 1:04. capeeia see 5 TE De 
Total impurities, including moisture.....-....-.----.--- 255 12s Ane 1 Bite sh ce toes 


The balance to be normal or basic lead sulphate. 

The paste shall be made by thoroughly grinding the above pig- 
ment with pure raw or refined linseed oil. The paste shall not 
cake in the container and shall break up readily in oil to form a 
smooth paint of brushing consistency. The paste shall consist of: 


Maximum.| Minimum, 


Per ee Per cent. 


Pigment... . slab snccsec ces ns Senin 0 cid senpecincwmssis dens ah ose ckedse dees see eh mak] ¢ eg GmeM naan eae avis 
Tilnseed Ole eo or re se esc case pees te mens opin mine eet <ln nals = mieie eae see 12.0 
Moisture and other volatile matter... ......-..- +2. ses eee eee ee eee ee eee eter wees OS tan passa. a» 
Coarse particles and “‘skins” (total residue left on No. 325 screen based on pigment) Cp ee Pet eS 


Notr.—Deliveries will, in general, be sampled and tested by the following methods, but the pur- 
chaser reserves the right to use any additional available information to ascertain whether the material 
meets the specification. 


2, SAMPLING. 


It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1,000 packages shall be taken as 
representative of the whole. 


With the dry pigment, the package is to be opened be the in- | 


spector and a sample of not less than 5 pounds taken at random 
from the contents and sent to the laboratory for test. 

With the paste, whenever possible, an original unopened con- 
tainer shall be sent to the laboratory, and when this is for any 
reason not done, the inspector shall determine, by thorough 
testing with a paddle or spatula, whether the material meets the 
requirement regarding not caking in the container. (See 4 (a) 
After assuring himself that the paste is not caked in the con- 
tainer, the inspector shall draw a sample of not less than 5 pounds 
of the thoroughly mixed paste, place it in a clean dry metal or 
glass container, which must be filled with the sample, closed with 


P 


Specification for Leaded Zinc Oxide, Dry and Paste zB 


a tight cover, sealed, marked, and sent to the laboratory for test 
with the inspector’s report on caking in container. 

When requested, a duplicate sample may be taken from the 
saine package and delivered to the seller, and the inspector may 
take a third sample to hold for test in case of dispute. 


3. LABORATORY EXAMINATION OF DRY PIGMENT. 


(a) CoLror.—Take 5 g of the sample, add 1.5 cc of linseed oil, 
rub up on a stone slab or glass plate with a flat-bottomed glass 
or stone pestle or muller to a uniform smooth paste. Treat in 
a similar manner 5 g of the standard leaded zinc oxide: Spread 
the two pastes side by side on a clear colorless glass plate and 
compare the colors. If the sample is as white or whiter than the ~ 
‘“‘standard,’’ it passes this test. If the ‘standard’ is whiter 
than the sample, the material does not meet the specification. 

(b) CoLoR STRENGTH.—Weigh accurately 0.01 g of lampblack, 
place on a large glass plate or stone slab, add 0.2 cc of linseed oil, 
and rub up with a flat-bottomed glass pestle or muller; then add 
exactly 10 g of the sample and 2.5 cc of linseed oil, and grind 
with a circular motion of the muller 50 times; gather up with a 
sharp-edged spatula and grind out twice more in a like manner, 
giving the pestle a uniform pressure. Treat another 0.01 g of 
the same lampblack in the same manner, except that 10 g of 
standard leaded zinc oxide is used instead of the 10 g of the sam- 
ple. Spread the two pastes side by side on a glass microscope 
slide and compare the colors. If the sample is as light as or lighter 
in color than the ‘‘standard,’’ it passes thistest. Ifthe ‘‘standard’”’ 
is lighter in color than the sample, the material does not meet 
the specification. 

(c). Coarse ParTICLES.'—Dry in an oven at 105° to 110° C. 
a 325 screen, cool and weigh accurately. Weigh 10 g of the 


sample; dry at 100° C., transfer to a mortar, add 100 cc kero- 


sene, thoroughly mix by gentle pressure with a pestle to break up 
all lumps, wash with kerosene through the screen, breaking up all 
lumps, but not grinding. After washing with kerosene until all 
but the particles which are too coarse to pass the screen have been 
washed through, wash all kerosene from the screen with ether or 
petroleum ether, heat the screen for one hour at 105° to EIQ ty: 
cool and weigh. 


1 For a general discussion of screen tests of pigments and data regarding many pigments on the market, 
see Circular No. 148 of the Educational Bureau, Scientific Section, Paint Manufacturers’ Association of 
the U.S. 


4 Circular of the Bureau of Standards 


(d) QUALITATIVE ANALyYsIs.—Test for matter insoluble in hydro- 
chloric acid, lead, calcium, carbon dioxide, etc., by snips cbsooins 
of qualitative analysis. 

(ec) MotsturE.—Place 1 g of the sample in a wide-mouth short 
weighing tube provided with a glass stopper. Heat badneiees. <0) 
removed for two hours at a temperature between 105 and 110° C. 
Insert stopper, cool, and weigh. Calculate loss in west as 
moisture. 

(f) WATER SOLUBLE SALTs.—To Io g of ipwiet ina $06 ce 
volumetric flask, add 200 ce of water, boil for five minutes, 
- nearly fill the flask with hot water, allow to cool, fill to mark, mix, 
filter through a dry paper, discard the first 50 ce of filtrate, 
transfer 100 cc of the filtrate (corresponding to 2 g of sample) 
to a weighed dish, Rpatieein to dryness, heat for one hour in an 
oven at 105 to 110° C., cool, and weigh, calculate to ais 
of water soluble salts. 

(9) Zinc Ox1pE.— Weigh accurately about 0.3 g of the pigment, 
transfer to a 400 cc beaker, add 30 ce of hydrochloric acid 
(1 :2), boil for two or three minutes, add 200 ce of water and 
a small piece of litmus paper; add ammonium hydroxide until 
slightly alkaline, render just acid with hydrochloric acid, then add 
3 cc of strong hydrochloric acid, heat nearly to boiling, and 
titrate with standard potassium ferrocyanide as in standardizing 
the solution. (See Reagents 5 (d).) Calculate total zine as ZnO. 

(h) CaLCULATIONS.—If, as will be the case with material com- 
plying with the specification, no metals but zine and lead are 
found by qualitative tests, add the percentage of ZnO, moisture, 
and water soluble salts and subtract the sum from 100. ee the 
remainder ‘‘normal and basic lead sulphate.” 


4, LABORATORY EXAMINATION OF PASTE. 


(a) CAKING IN CONTAINER.—When an original package is re- 
ceived in the laboratory, it shall be weighed, opened, and stirred 
with a stiff spatula or paddle. The paste must be no more diffi- 
cult to break up and show no more caking than a normal good 
grade of leaded-zinc oxide paste. The paste shall be finally 
thoroughly mixed, removed from the container, the container 
wiped clean, and weighed. This weight subtracted from the 
weight of the original package gives the net weight of the con- 
tents. A portion of the thoroughly mixed paste shall be placed — 
in a clean container and the portions for the remaining tests 
promptly weighed out. 


Specification for Leaded Zinc Oxide, Dry and Paste 5 


(b) MIXING WITH LINSEED O1L.—One hundred grams of the paste 
shall be placed in a cup, 35 cc of linseed oil added slowly with 
| careful stirring and mixing with a spatula or paddle, the resulting 

‘ mixture must be smooth and of good brushing consistency. 

(c) MoistuRE AND OTHER VOLATILE MatTrer.—Weigh accu- 
rately from 3 to 5 g of the paste into a tared flat-bottomed dish » 
about 8 cm in diameter, spreading the paste over the bottom. 
Heat at 105 to 110° C. for three hours, cool, and weigh. Calculate 

: loss in weight as percentage of moisture and other volatile matter. 

: (d) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 g 

-of the paste into a weighed centrifuge tube. Add 20 to 30 cc 

‘“‘extraction mixture’’ (see Reagents), mix thoroughly with a glass 

rod, wash the rod with more of the extraction mixture, add. suffi- 

cient of the reagent to make a total of 60 cc in the tube. Place 
the tube in the container of a centrifuge, surround with water, 

and counterbalance the container of the opposite arm with a 

similar tube or a tube with water. Whirl at a moderate speed 

until clear. Decant the clear supernatant liquid. Repeat the 
extraction twice with 4o cc of extraction mixture, and once with 

4o ce of ether. After drawing off the ether, set the tube in a 

beaker of water at about 80° C. or on top of a warm oven for 10 

: minutes, then in an oven at 105 to 110° C. for two hours. Cool, 

weigh, and calculate percentage of pigment. 

(ec) EXAMINATION OF PIGMENT.—Grind the pigment from (d) 
to a fine powder, pass through a No. 80 screen to remove any 

“skins,’’ preserve in a stoppered tube, and apply tests 3 (d), (/), 


ia 


: (g), and (kh). If required, apply tests 3 (a) and (b) in comparison 
. _ with a portion of pigment extracted from the standard paste in 
q exactly the same manner as in extracting the sample. 

4 (f) PREPARATION oF Farry Acips.—To about 25 g of the 
4 paste in a porcelain casserole, add 15 ce of aqueous sodium hy- 
P droxide (see Reagents) and 75 ce of ethyl alcohol; mix, and heat 
3 uncovered n a steam bath until saponification is complete (about 
4 one hour). Add 100 cc of water, boil, add sulphuric acid of 
. specific gravity 1.2 (8 to 10 cc in excess); boil, stir, and trans- 
4 fer to a separatory funnel, to which some water has been pre- 
q viously added. Draw off as much as possible of the acid aqueous 
4 layer and lead sulphate precipitate, wash once with water, then 
at add 50 cc of water and 50 cc of ether. Shake very gently with 
2 a whirling motion to dissolve the fatty acids in the ether, but 
. not violently, so as to avoid forming an emulsion. Draw off the 


6 Circular of the Bureau of Standards 


aqueous layer and wash the ether layer with one 15 ce portion of 
water and then with 5 cc portions of water until free from sul- 
phuric acid. Then draw off completely the water layer. Transfer 
the ether solution to a dry flask, add 25 to 50 g. of anhydrous 
sodium sulphate. Stopper the flask and let stand with occa- 
sional shaking at a temperature below 25° C. until the water is 
completely removed from the ether solution, which will be shown 
by the solution becoming perfectly clear above the solid sodium 
sulphate. Decant this clear solution (if necessary, through a dry 
filter paper) into a dry 100 ce Erlenmeyer flask. Pass a rapid 
current of dry air (pass through CaCl, tower) into the mouth of the 
Erlenmeyer flask and heat to a temperature below aa i on a dry 
hot plate until the ether is entirely driven off. 


NoTE.—It is important to follow all of the details, since ether generally contains 


alcohol and after washing with water always contains water. It is very difficult 
to remove water and alcohol by evaporation from fatty acids, but the washing of the 
ether solution and subsequent drying with anhydrous sodium sulphate removes both 
water and alcohol. Ether, in the absence of water and alcohol, is easily removed 
from fatty acids by gentle heat. 

The fatty acids prepared as above should be kept in a stoppered 
flask and examined at once. 

(g) TEST FOR MINERAL OIL AND OTHER UNSAPONIFIABLE MAT- 
TER.—Place ro drops of the fatty acid (/) in a 50 ce test tube, add 
5 cc of alcoholic soda (see Reagents), boil vigorously for five 
minutes, add 40 cc of water and mix; a clear solution indicates 
that not more than traces of unsaponifiable matter are present. 
If the solution is not clear, the oil is not pure linseed oil. 

(h) IoDINE NUMBER OF Farry Acips.—Place a small quantity 
of the fatty acids (f) in a small weighing burette or beaker. Weigh 
accurately. Transfer by dropping about 0.15 g (0.10 to 0.20 g) 
to a 500 cc bottle having a well-ground glass stopper or an Erlen- 
meyer flask having a specially flanged neck for the iodine test. 
Reweigh the burette or beaker and determine the amount of sample 
used. Add 1occof chloroform. Whirl the bottle to Gissolve the 
sample. Add 1o cc of chloroform to two empty bottles like that 
used for the sample. Add to each bottle 25 cc of the Hanus solu- 
tion (see Reagents) and let stand with occasional shaking for one- 
half hour. Add 10 cc of the 15 per cent potassium iodide solu- 
tion and roo ce of water and titrate with standard sodium thio- 
sulphate, using starch as indicator. ‘The titrations on the two 
blank tests should agree within 0.1 ce. From the difference be- 
tween the average of the blank titrations and the titration on the 


Specification for Leaded Zinc Oxide, Dry and Paste 7 


sample and the iodine value of the thiosulphate solution calculate 
the iodine number of the sample tested. (Iodine number is centi- 
grams of iodine to 1 g of sample.) If the iodine number is less 
than 170, the oil does not meet the specification. 

(2) COARSE PARTICLES AND ‘‘SKINS.”’—Weigh an amount of 
paste containing 10 g of pigment (see 4(d)), add 100 g of kerosene | 
and wash through a No. 325 screen. ‘he residue is reported as 
“coarse particles and ‘skins.’ ”’ 


5. REAGENTS. 


(a) URANyL INDICATOR FoR ZINC TITRATION.—A 5 per cent 
solution of uranyl nitrate in water or a 5 per cent solution of 
uranyl acetate in water made slightly acid with acetic acid. 

(b) STANDARD POTASSIUM FERROCYANIDE.—Dissolve 22 g of 
the pure salt in water and dilute to 1,000 cc. To standardize, 
transfer about 0.2 g (accurately weighed) of pure metallic zine or 
freshly ignited pure zinc oxide to a 400 cc beaker. Dissolve in 
ro cc of hydrochloric acid and 20 cc of water. Drop in a small 
piece of litmus paper, add ammonium hydroxide until slightly 
alkaline, then add hydrochloric acid until just acid and then add 
3 ce of strong hydrochloric acid. Dilute to about 250 cc with 
hot water and heat nearly to boiling. Run in the ferrocyanide 
solution slowly from a burette with constant stirring until a drop 
tested on a white porcelain plate with a drop of the uranyl indi- 
cator shows a brown tinge after standing one minute. A blank 
should be run, using the same amounts of reagents and water as in 
the standardization. The amount of ferrocyanide solution re- 
quired for the blank should be subtracted from the amounts used 
in standardization and in titration of the sample. The standardi- 
zation must be made under the same conditions of temperature, 
volume, and acidity as obtain when the sample is titrated. 

(c) BARIUM CHLORIDE SOLUTION.—Dissolve 100 g of pure 
crystallized barium chloride in water and dilute to 1,000 cc. 

(d) STANDARD SODIUM THIOSULPHATE SOLUTION.—Dissolve pure 
sodium thiosulphate in distilled water that has been well boiled 
to free it from carbon dioxide, in the proportion of 24.83 g of 
crystallized sodium thiosulphate to 1,000 cc of the solution. It 


‘is best to let this solution stand for about two weeks before stand- 


ardizing. Standardize with pure resublimed iodine (See Ana- 
lytical Chemistry, Treadwell-Hall, 2, 3d ed., p. 646). This solu- 
tion will be approximately decinormal, and it is best to leave it as 


8 Circular of the Bureau of Standards 


it is after determining its exact iodine value, rather than to 
attempt to adjust it to exactly decinormal. Preserve in a stock 
bottle provided with a guard tube filled with soda lime. 

(e) STARCH SOLUTION.—Stir up 2 to 3 g of potato starch or 5 g 
of soluble starch with 100 ce of 1 per cent salicylic acid solution, 
add 300 to 400 ce of boiling water, and boil the mixture until the 
starch is practically dissolved, then dilute to 1 liter. | 

(f) EXTRACTION MIxTURE.— 

10 volumes ether (ethyl ether). 
6 volumes benzol. 
4 volumes methyl alcohol. 
I volume acetone. 

(9) AQUEOUS Sop1um HypRoxIDE.—Dissolve 100 g of sodium 
hydroxide in distilled water and dilute to 300 ce. 

(h) Potassium IopIDE SoLUTION.—Dissolve 150 g of potassium 
iodide free from iodate, in distilled water and dilute to 1,000 cc 

(1) Hanus SOLUTION.—Dissolve 13.2 g of iodine in 1,000 cc of 
99.5 per cent glacial acetic acid, which will not reduce chromic 
acid. Add enough bromine to double the halogen content, deter- 
mined by titration (3 cc of bromine is about the proper amount). 
The iodine may be dissolved by the aid of heat, but the ia wis 
should be cold when the bromine is added. 

(7) ALCOHOLIC SoDIUM HyDROXIDE SOLUTION.—Dissolve pure 
sodium hydroxide in 95 per cent ethyl alcohol in the proportion 
of about 22 g per 1,000 cc. Let stand in a stoppered bottle. 
Decant the clear liquid into another bottle, and keep well stop- 
pered. ‘This solution should be colorless or only slightly yellow 
when used, and it will keep colorless longer if the alcohol is pre- 
viously treated with sodium hydroxide (about 80 g to 1,000 cc), 
kept at about 50° C. for 15 days, and then distilled. 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 
5 CENTS PER COPY 


. . 
WASHINGTON : GOVERNMENT PRINTING OFFICH ! 1924 ; 


U. S. Gov't 
Master 
Specification 


No. 10b 
DEPARTMENT OF COMMERCE 


BUREAU OF STANDARDS 


George K. Burgess, Director 


CIRCULAR OF THE BUREAU OF STANDARDS, No. 89 


[3d edition. Issued April 25, 1927] 


UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
PAINT, WHITE, AND TINTED PAINTS MADE ON A WHITE 
BASE, SEMIPASTE AND READY MIXED ° 


FEDERAL SPECIFICATIONS BOARD, SPECIFICATION No. 10b 
[Revised as of Sept. 2, 1925] 


This specification was officially adopted by the Federal Specifications Board 
on February 3, 1922, for the use of the departments and independent estab- 
lishments of the Government in the purchase of white paint and tinted 
paints made on a white base, semipaste and ready mixed. 

[The date on which the technical requirements of this revision of this specification became manda- 
tory for all departments and independent establishments ofthe Government was September 2, 1925. 
The changes included in this revision were authorized by the Federal Specifications Board and 
promulgated in a circular letter on above revision date.] 


CONTENTS 
Page 
a "General speciiicdtidiis s). Sie. fh SL 2aU et Re 2 
Pe eee se Ae Gia eel Le oes o..phaee - a> 2 
Tih anatena eneworkmansbip....4 oo 4<- La) vee —~aepe- ec lanrl-wae 2 
Pe Aaeerral eriiremenias eg 4 eh i E deg oa eee 2 
Peer PP ITOUSOING is ca aa ke eRe COR nly ee ee 2 
ST i pile SS acl AR icc Me fe Bak = of EG ei Ray i antag Sapp 2 
Oe Tet FR Piel OD OU ADE ule. Nel ie BO ee 3 
eibomimete (60h iG ici suee worl). aie -68 - gidseey 3 
Ss) Meadyemined paints sola ln - asym t pee bee -srra ee nT 3 
VI. Methods for sampling and testing. --___----------------------- 4 
MINS ENE hu! ciciiidg de sald ck op salah od Sal te be oo ee en 2 4 
2. Laboratory examination—semipaste.___..-.------------- 4 
OY Analysis’ of pigmentlit Oh cael eh a ek ea 7 
4. Laboratory examination—mixed paint___...------------- 8 
im Béagenta cece ssl) at ache eeoeeas - ond} -sabery- eS 9 
VII. Packing and marking of shipments_-_.-------------------+----- 11 
EES SOEUR RE: ice PRS SUPA Ren Cin SEs oe ee oy MOINES PRY MR ARAL 7 SP ee 11 


a eee ee a en PD AO ea arn i So ee 

1 It is believed that this specification admits practically all high-grade lead-zinc prepared paints generally 
available in the United States, and which are therefore obtainable without requiring manufacturers to 
make up special lots. On large contracts for which paint will be specially made, the purchaser may require 
the bidder to submit the formula of the paint he proposes to furnish as conforming to the specifications. 


43255°—27 


2 CIRCULAR ty THE BUREAU OF STANDARDS 
I. GENERAL SPECIFICATIONS 
There are no general specifications applicable to this specification. 
II. TYPES 


White paint and tinted paints made on a white base shall be of 
the following types: Semipaste in linseed oil and ready-mixed. 


Ill. MATERIAL AND WORKMANSHIP 
See detail requirements. Be 
IV. GENERAL REQUIREMENTS 
See detail requirements. | 
V. DETAIL REQUIREMENTS 
1, PIGMENT 


The pigment shall be composed of: 


Maximum | Minimum 


Per cent Per cent © 
White lead (basic carbonate, basic sulphate, or a mixture thereof)..........--..- 70 45 


Hing oxide (ZNO) ait cnvae saeweeve penta sedan =e snare ~neiapieiuntenan apendimatennien ears aes 55 30 
White mineral pigments, containing no lead or zinc compounds, pure tinting 
Colors, Or ANY MIXtUTe PHeCTEOL..-.~. 5. eos caste ccs noadedcetteane eth e ee see eee 15 


In no case shall the sum of the basic lead carbonate, basic lead 
sulphate, and zinc oxide be less than 85 per cent. The lead and 
zinc pigments may be introduced in the form of any mixture pre- 
ferred of basic carbonate white lead, basic sulphate white lead, zinc 
oxide, or leaded zinc, provided the above requirements as to composi- 
tion are met. The total lead dissolved by dilute acetic acid and hot 
acid ammonium acetate, weighed as lead sulphate, and this weight 
multiplied by the factor 0.883 shall be considered white lead. It is 
not possible to determine the amount of lead carbonate and lead 
sulphate when carbonates or sulphates of other metals, such as 
calcium, are present. Also neither basic lead carbonate nor basic 
lead sulphate are definite compounds. ‘The factor to convert PbSQ, 
to (PbCO;), Pb(OH)s is 0.854, to convert PbSO, to PbSO,PbO is 
0.868, and to convert PbSO, to (PbSQO,). PbO is 0.918. The arbitrary 
factor used under this specification is the mean of the largest and 
smallest of these three factors. aid 


SPECIFICATION FOR WHITE PAINT AND TINTED PAINTS 3 
2. LIQUID 


The liquid in semipaste paint shall be entirely linseed oil; in ready- 
mixed paint it shall contain not less than 90 per cent linseed oil, 
the balance to be combined drier and thinner. The thinner shall be 
turpentine, volatile mineral spirits, or a mixture thereof. 


3. SEMIPASTE 


Semipaste shall be made by thoroughly grinding the pigment with 
linseed oil. 

The semipaste as received and three months thereafter shall be 
not caked in the container and shall break up readily in linseed 
oil to form a smooth paint of brushing consistency. It shall “mix 
readily with linseed oil, turpentine, or volatile mineral ‘spirits, or 
any combination of these substances, in all proportions without 
curdling. ‘The color and hiding power when specified shall be equal 
to that of a sample mutually agreed upon by buyer and seller. The 
weight per gallon shall be not less than 19.0 pounds. The paste shall 
consist of: | 


Maximum | Minimum 


Per cent Per. cent 
77 73 


SSS EGS SUE en p-chadlbe: barnegat Ml: Site. able Ah Ahh pe i sedte shade’ 
oe 5 a Re RTS INS Ce aS ai a a ee BEES De OREN AES 27 23 
Moisture and otherwolatilempatter. . noe cso Sse asd eee 9 ek ek aS hk MAE eo Se 
Coarse particles and “skins’’ (total residue retained on No. 325 screen based on 

I pA i cee ne ees 


4. READY-MIXED PAINT 


Ready-mixed paints shall be well ground, shall not settle badly or 
cake in the container, shall be readily broken up with a paddle to a 
smooth uniform paint of good brushing consistency, and shall dry 
within 18 hours to a full oil gloss, without streaking, running, or 
sagging. The color and hiding power when specified shall be equal 
to those of a sample mutually agreed upon by buyer and seller. .The 
weight per gallon shall be not less than 1534 pounds. The paint 
shall consist of: | 


Maximum | Minimum 


Per cent Per cent 


4 CIRCULAR OF THE BUREAU OF STANDARDS 
V. METHODS FOR SAMPLING AND TESTING 


Deliveries will, in general, be sampled and tested by the following 
methods, but the purchaser reserves the right to use any additional 
available information to ascertain. whether the material meets the 
specification. 7 cae | , 

1. SAMPLING 


‘It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1,000 packages shall be taken as 
representative of the whole. Whenever possible an original unopened 
container shall be sent to the laboratory, and when this is for any 
reason not done, the inspector shall determine by thorough testing 
with a paddle or spatula whether the material meets the requirement 
regarding caking inthe container. He-shall then thoroughly mix the 
contents of the container and draw a sample of not less than 5 pounds 
of the thoroughly mixed paint, place it in a clean; dry metal or glass 
container, which must be filled with the sample, closed with a tight 
cover, sealed, marked, and sent to the laboratory for test with the 
inspector’s report on caking in container. 

When requested, a duplicate sample may be taken from the same 
package and delivered to the seller, and the inspector may take a 
third sample to hold for test in case of dispute. 


2. LABORATORY EXAMINATION—SEMIPASTE 


(a) CaKING IN ConTAINER.—When an original package is received 
in the laboratory it shall be weighed, opened, and stirred with a stiff 
spatula or paddle. The paste must be no more difficult to break up 
than a normal good grade of semipaste paint. The semipaste shall 
finally be thoroughly mixed, removed from the container, and the 
container wiped clean and weighed. This weight subtracted from 
the weight of the original package gives the net weight of the contents. 
A portion of thoroughly mixed semipaste shall be placed in a clean 
container and the portions for the remaining tests promptly weighed 
out. ; 

(b) Cotor.—Place some of the paint on a clean, clear glass plate. 
Place some of the standard agreed upon beside the sample on the 
plate, turn the glass over, and compare the colors. 

(c) Wrrcur PeER GALLON.—From the weight of a known volume 
of the paste calculate the specific gravity, which multiplied by 8.33 
gives the weight in pounds per gallon. Any suitable container of 
known volume may be used for the purpose,. but a short cylinder of 
heavy glass with rounded bottom about 75 mm high and having a 
capacity of from 125 to 175 cc (a glass cap to keep dust from reagent 
bottle stopper) is a convenient apparatus for the purpose. The 


SPECIFICATION FOR WHITE PAINT AND TINTED PAINTS 5 


capacity of this vessel is determined to within 1 cc. The paste is 
packed into it until completely full, the top leveled off smooth with 
a spatula, and weighed to +0.5g. Subtract the weight of the empty 
container and divide the remainder by the number of cubic centi- 
meters representing the capacity of the container. The quotient is 
the specific gravity, which can be thus determined within +2 in the: 
second decimal place. 

(d) Mrixine wira Linsrrp O1nt.—One hundred grams of ‘the 
paste shall be placed in a cup, 18 cc linseed oil added slowly with 
careful stirring and mixing with a spatula or paddle. The resulting 
mixture must be smooth and of good brushing consistency. 

(e) Moisture anp OTHER Vo.uaTineE Marrer.—Weigh accu- 
rately from 3 to 5 g of the paste into a tared flat-bottomed dish about 


8 cm in diameter, spreading the paste over the bottom. Heat at 


105 to 110° C. for three hours, cool, and weigh. Calculate loss in 
weight as percentage of moisture and volatile matter. 

(f{) PercentTaGEe or Picment.—Weigh accurately about 15 g of 
the paste into a weighed centrifuge tube. Add 20 to 30 cc of 
“extraction mixture” (see Reagents), mix thoroughly with a glass 
rod, wash the rod with more of the extraction mixture, and add 
sufficient of the reagent to make a total of 60 cc in the tube. Place 
the tube in the container of a centrifuge, surround with water, and 
counterbalance the container of the opposite arm with a similar 
tube or a tube with water. Whirl at a moderate speed until well 
settled. Decant the clear supernatant liquid. Repeat the extrac- 
tion three times with 40 cc of extraction mixture. After drawing off 


- the extraction mixture, set the tube in a beaker of water at about 80° 


C. or on top of a warm oven for 10 minutes, then in an oven at 
105 to 110° C. for two hours. Cool, weigh, and calculate the per- 
centage of pigment. Grind the pigment to a fine powder, pass through 
a No. 80 screen to" remove any skins, and preserve in a . stoppered 
bottle. - 

(g) PREPARATION oF Farry Acips.—To about 25 g of the paste 
in’ a porcelain casserole, add 15 cc of aqueous sodium hydroxide 
(see Reagents) and 75 cc of ethyl alcohol mix and heat uncovered 
on a steam bath until saponification is complete (about one hour). 
Add 100 ce of water, boil, add sulphuric acid of specific gravity 1.2 
(8 to 10 cc in excess), boil, stir, and transfer to a separatory funnel 
to which some water has been previously added. Draw off as much 
as possible of the acid aqueous layer and lead sulphate precipitate, 
wash once with water, then add 50 cc of water and 50 cc of ether. 
Shake very gently with a whirling motion to dissolve the fatty acids 
in the ether, but not so violently as to form an emulsion. Draw off 
the aqueous layer and wash the ether layer with one 15 ce portion of 
water and then with 5 cc portions of water until free from sulphuric 


6 CIRCULAR‘ OF THE BUREAU OF STANDARDS © 


acid. Then draw off the water layer completely. Transfer the ether 
solution to a dry flask and add 25 to 50 g anhydrous sodium sulphate. 
Stopper the flask and let stand with occasional shaking at a tem- 
perature below 25° C. until the water is completely removed from 
the ether solution, which will be shown by the solution becoming 
perfectly clear above the solid sodium sulphate. Decant this clear 
solution, if necessary through a dry filter paper, into a dry 100 ce 
Erlenmeyer flask. Pass a rapid current of dry air (pass through a 
CaCl, tower) into the mouth of the Erlenmeyer flask and heat to a 
temperature below 75° C. on a dry hot plate until the ether is entirely 
driven off. 

‘Nots.—It is important to follow all of the details, since ether generally con- 
tains alcohol and after washing with water always contains water. It is very 
difficult to remove water and alcohol by evaporation from fatty acids, but the 
washing of the ether solution and subsequent drying with anhydrous sodium 
sulphate removes both water and alcohol. Ether, in the absence of water and 
alcohol, is easily removed from fatty acids by gentle heat. 

The fatty acids prepared as above should be kept in a stoppered 
flask and examined at once. 

(hk) Test ror MINERAL OIL AND. OTHER pC ro. ‘pat 
TER.—Place 10 drops of the fatty acid (g) in a 50 cc test tube, add 
5 cc of alcoholic soda (see Reagents), boil vigorously for five minutes, 
add 40 cc of water, and mix; a clear solution indicates that not more 
than traces of unsaponifiable matter are present. If the solution is 
not clear, the oil is not pure linseed oil. | 

({) Iopins Numsper or Farry Actps.—Place a small. quantity of 
the fatty acids (g) in a small weighing burette or beaker. Weigh 
accurately. Transfer by dropping from 0.09 g to 0.15 g into a 
500 cc bottle having a well-ground glass stopper, or an Erlenmeyer 
flask having a specially flanged neck for the iodine test. Reweigh 
the burette or beaker and determine amount of sample used. Add 
10 cc of chloroform. Whirl the bottle to dissolve the sample. Add 
10 cc of chloroform. to each of two empty bottles like that used for 
the sample. Add to each bottle 25 cc of the Wijs solution (see 
Reagents) and let stand with occasional shaking for one hour in a 
dark place at a temperature of from 21 to 23°'C. Add 10 cc of the 
15 per cent. potassium iodide solution and 100 cc of water, and titrate 
with standard sodium thiosulphate using starch as indicator. The 
titrations on the two blank tests should agree within 0.1 cc. From 
the difference between the average of the blank titrations and the 
titration on the sample and the iodine value of the thiosulphate 
solution, calculate the iodine number of the sample tested. (lodine 
number is centigrams of iodine to 1 g of sample.) If the iodine 
number is less than 175, the oil does not meet the specification. 

(j) Coarse ParticLes aND Sxins,—-Dry in an oven at 105 to 
110° C. a No. 325 screen, cool, and weigh accurately. Weigh an 


SPECIFICATION FOR WHITE PAINT AND TINTED PAINTS ’f 


amount of semipaste containing 10 g of pigment (see 2 (f)), add 100 cc 
of kerosene, mix thoroughly, and wash with kerosene through the 
screen, breaking up all lumps, but not grinding. After washing with 
kerosene until all but the particles too coarse to pass the screen have 
been washed through, wash all kerosene from the screen with ether 
or petroleum ether, heat the screen i one hour at 105 to 110° C., 
cool, and weigh. 


3. ANALYSIS OF PIGMENT 


(2) Quatirative ANaztysis.—A complete qualitative analysis fol- 
lowing the well-established methods is always advisable, but the work 
may be usually very much shortened by adding acetic acid slowly to 
the pigment until all carbonate is decomposed (noting whether any 
hydrogen sulphide is evolved), then adding a large excess of acid 
ammonium acetate, boiling, filtering, and testing the filtrate for 
metals other than lead and zine (especially calcium and barium). 
The absence of calcium in this filtrate indicates that the extending 
pigments contain no calcium carbonate or calcium sulphate; the 
absence of barium indicates that the extending pigments contain no 
barium carbonate. Test another portion of pigment with hydro- 
chloric acid (1:1). No odor of hydrogen sulphide should develop. 

(6) Wuitt Leap.—Weigh accurately about 1 g of the pigment, 
transfer to a 250 ce beaker, moisten with a few drops of alcohol, add 
slowly dilute (about 20 per cent) acetic acid until all carbonate is 
decomposed (no further effervescence), then add 50 cc of acid am- 
monium acetate solution (see Reagents), and boil for two minutes. 
Decant through a weighed Gooch crucible, leaving any undecom- 
posed matter in the beaker. Wash the Gooch crucible with a small 
amount (about 20 cc) of hot water. To the residue in the beaker 
add 50 cc of the acid ammonium acetate solution and boil two 
minutes. Filter through the same Gooch crucible, transferring the 
insoluble matter to the crucible, and wash thoroughly with hot 
water. Dry the crucible at 105 to 110° C., cool, and weigh. In 
cases where siliceous material was used as the white extending pig- 
ments, the material retained on the Gooch crucible will approximate 
the amount of white extending and tinting pigments. 

Unite the filtrates and pass in a stream of hydrogen sulphide to 
complete precipitation; let the mixed sulphides of lead and zinc 
settle, filter on paper, wash with water containing hydrogen sulphide, 
dissolve the sulphides in hot nitric acid (1:3), and determine lead as 
sulphate in the usual manner, weighing as PbSO, Multiply lead 
sulphate weight by the factor 0.883 and report as white lead. 

(c) Zinc Oxtpr.—Weigh accurately about 0.5 g of the pigment, 
transfer to a 400 cc beaker, add 30 cc of hydrochloric acid (1:2), boil 
for two or three minutes, add 200 cc of water and a small piece of 


8 CIRCULAR OF THE BUREAU OF STANDARDS. 


litmus paper; add strong ammonia until slightly alkaline, render just 
acid with hydrochloric acid, then add 3 cc of strong hydrochloric acid, 
heat nearly to boiling, and titrate with standard ferrocyanide as in 
standardizing that solution (see Reagents). Calculate total zine as 
zine oxide. 

(d) CaLouLATIONS.—Add the percentage of white lead (see 3(6)), 
zinc oxide (see 3 (c)), and subtract from 100; the remainder is reported 
as extending and tinting pigments. 


4. LABORATORY EXAMINATION—MIXED PAINT 


(2) Caxine 1n Container.—Follow the procedure outlined in 2(a), 
noting that the paint should be no more difficult to break up than a 
good grade of mixed paint. 

(6) Cotor.—Follow the procedure outlined in 2 (6). 

(c) WricuT per GaLLton.—Weigh a clean, dry, 100 cc graduated 
flask. Fill to the mark with the thoroughly mixed paint and weigh 
again. The increase in weight expressed in grams, divided by 100, 
gives the specific gravity, which multiplied by 8.33 gives the weight 
in pounds per gallon. 

(d) Brusninc Propertizs AND Time or Dryina.—Brush the 
well-mixed paint on a suitable panel, which may be ground glass, 
steel, or well-filled wood. Note whether the paint works satis- 
factorily under the brush. Place the panel in a vertical position 
in a well-ventilated room and let stand for 18 hours. The paint 
should be dry and free from streaks. Flow a portion of the paint on 
a clean glass plate. Let dry in a nearly vertical position at room 
temperature (65 to 100° F.). The film shall show no streaking or 
separation within a distance of 4 inches from the top. 

(e) Warrer.—Mix 100 g of the paint in a 500 cc short-neck glass 
flask * with 75 cc of toluol (free from water). Connect with the 
distilling trap and condenser and heat so that the condensed distillate 
falls from the end of the condenser at the rate of from two to five 
drops per second. Continue the distillation at the specified rate 
until no water is visible on any part of the apparatus except at the 
bottom of the trap. This operation usually requires less than an 
hour. A persistent ring of condensed water in the condenser tube 
should be removed by increasing the rate of distillation for a few 
minutes. The number of cubic centimeters of condensed water 


measured in the trap at room temperature is the percentage of | 


water in the paint. q 
(f) Votatity THInneR.—Follow the procedure outlined in 2 (e). | 


Correct the result for any water found (see 4 (e)) and report the 


remainder as volatile thinner. 


1 The apparatus for determining water is that described in ‘‘Standard method of test for water in petro- 


leum products and other bituminous materials,’”’ serial designation D-95-24, A. 8. T. M. Standards, 1924, 
p. 901, and Figure 1 (6) and (c), p. 902. 


i 
7 
. 


SPECIFICATION FOR WHITE PAINT AND TINTED PAINTS 9 


(9) PERCENTAGE oF PIGMENT. Follow the ' aki outlined 
in 2 (f). 

(h) Tzstina NoNVOLATILE Vienvseil —Follow the procedure out- 
lined in 2 (g), 2 (h), and 2 (%), except that in the preparation of 
the fatty acids the mixture of paint and alkali is heated on the 
steam bath until all volatile thinner is driven off. 

(1) Coarse PARTICLES AND SKINS. —Follow the Peden out- | 
lined in 2 (J). 

(j) Tzestinc Pigment.—Follow the procedure outlined in 3 (a) 
to 3 (d), inclusive. 

5. REAGENTS 


(a) Actp Ammonium AcxrtTarn Soxiution.—Mix 150 cc of 80 
per cent acetic acid, 100 .cc of water, and 95 cc of strong ammonia 
(specific gravity, 0.90). 

(b) URANYL InpicaTor For Zinc Tirration.—A 5 per cent. 
solution of uranyl nitrate in water or a 5 per cent solution of uranyl 
acetate in water made slightly acid with acetic acid. 

(c) STANDARD Porasstum FrrRocyanipe.—Dissolve 22 g of the 
pure salt’in water and dilute to 1,000 cc. To standardize, transfer 
about 0.2 g (accurately weighed) of pure metallic zinc or freshly 
ignited pure zinc oxide to a 400. cc beaker. Dissolve in 10 ec of 
hydrochloric acid and 20 cc of water. Drop in a small piece of 
litmus paper, add ammonium hydroxide until slightly alkaline, then 
add hydrochloric acid until just acid, and then 3 cc of strong hydro- 
chloric acid. Dilute to about 250 cc with hot water and heat nearly 
to boiling. Run in the ferrocyanide solution slowly from a burette 
with constant stirring until a drop tested on a white porcelain plate 
with a drop of the uranyl indicator shows a brown tinge after stand- 
ing one minute. A blank should be run with the same amounts of 
reagents and,water as in the standardization. The amount of 
ferrocyanide solution required for the blank should be subtracted 
fromm the amounts used in standardization and in titration of the 
sample. The standardization must be made under the same con- 
ditions of temperature, volume, and acidity as obtained when the 
sample is titrated. 

(d) STANDARD SopiuM Deigdeesiwerd SoLution.—Dissolve pure — 
sodium thiosulphate in distilled water (that has been well boiled 
to' free it from carbon dioxide) in the proportion of 24.83 ¢ crystal- 
lized sodium thiosulphate to 1,000 cc of the solution. It is best to 
let this solution stand for about two weeks before standardizing. 
Standardize with pure resublimed iodine. (See Treadwell-Hall, 
Analytical Chemistry, vol. 2. 6th ed., p. 551.) This solution will 
be approximately decinormal, and it is best to leave it as it is after 
determining its exact iodine value, rather than to attempt to adjust 


(10 CIRCULAR OF THE BUREAU OF STANDARDS - 


it to exactly decinormal. Preserve in a stock bottle provider with 
a guard tube filled with soda lime. 

(e) Srarcu SonvuTion.—Stir up 2 to.3.g of potato starch or 5 g 
of soluble starch with 100 ce of 1 per cent salicylic acid solution, 
add 300 to 400 cc boiling water, and boil the mixture until the starch 
is practically dissolved,,then dilute to 1 liter; 

(f) Extraction Mixturt.— .- 

10 volumes ether (ethyl ether). 
6. volumes benzol. 
4 volumes methy] alcohol. 


1 volume acetone: 
(g) Aqurous Soprum Hyproxipz.—Dissolve 100 g of apres 


hydroxide in distilled water and dilute to 300 ce! 

(h) Potasstum Iopipn Sotutron.—Dissolve 150 g° of polar ten 
iodide free from iodate in distilled water and dilute to'1j000 éc. 

(1) Wiss Sotution.—The preparation of the iodine monochloride 
solution presents no great difficulty, but it should be done with care 
and accuracy in order to obtain satisfactory results. ‘There shall be 
in the solution no sensible excess either of iodine or more particularly 
of chlorine over that required to form the monochloride. This con- 
dition is most satisfactorily attained by dissolving in the whole of 
the acetic acid to be used the requisite quantity of iodine, using 
gentle heat to assist the solution, if it is found necessary. Dissolve 
iodine in glacial acetic acid that has a melting point of 14.7 to 15° C. 
and is free from reducing impurities in the proportion so that 13 ¢ 
of iodine will be present in 1,000 ce of solution, Set aside a small 
portion of this solution while pure, and pass dry chlorine into the 
remainder until the halogen content of the solution is doubled. 
Ordinarily it will be found that by passing the chlorine into the main 
part of the solution until the characteristic color of free iodine has 
just been discharged, there will be a slight excess of chlorine which 
is corrected by the addition of the requisite amount of the unchlori- 
nated portion until all free chlorine has been destroyed. A slight 


excess =i iodine does little or no harm, but excess of" chlorine must be 
avoide 


(j) Auconotic Soprum Hyproxips Soivitbe paddies pure 
sodium hydroxide in 95 per cent ethyl alcohol in- the proportion of 
about 22 g per 1,000 ce. Let stand ina stoppered bottle. Decant 
the clear liquid into another bottle and keep well stoppered.. This 
solution should be colorless or only slightly yellow when used, and it 
will keep colorless longer if the: alcohol is’ previously treated’ with 
sodium hydroxide (about 80 g to 1,000 cc), oe at about aOR C. 
for 15 days, and then distilled. ne 


See 


SPECIFICATION FOR WHITE PAINT AND TINTED PAINTS 11 
VII. PACKING AND MARKING OF SHIPMENTS 


Shall be in accordance with commercial practice unless otherwise 
specified. 
VIII. NOTES 


White paint and tinted paints made on a white base may be ordered _ 
either in the form of semipaste pigment ground in linseed oil or 
ready-mixed paint. The semipaste may be purchased by net weight 
or by volume. The ready-mixed paint should be purchased by 
volume (231 cubic inches to the gallon). 

For formulas and methods of using this and other materials for 
similar purposes see Bureau of Standards Technologic Paper No. 274, 
entitled ‘“‘Use of United States Government Specification Paints and 
Paint Materials.”’ 


ADDITIONAL COPIES 


O¥ THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 


6 CENTS PER COPY 


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DEPARTMENT OF COMMERCE 
BUREAU OF STANDARDS 


S. W. STRATTON, Director 


CIRCULAR OF THE BUREAU OF STANDARDS 


No. 90 


(2d edition. Issued May 23, 1922] 


UNITED STATES GOVERNMENT SPECIFICATION FOR 
RED LEAD—DRY AND PASTE 


ee ee! 


FEDERAL SPECIFICATIONS BOARD 
STANDARD SPECIFICATION NO. 11 


This Specification was officially adopted by the Federal Specifications Board, 
on February 3, 1922, for the use of the Departments and Independent Establish- 
ments of the Government in the purchase of materials covered by it. 


CONTENTS 

Page 
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i. Hin ia da) a ns eso pale eye tik see Ae Aw wea aS ae Coles 3 
De mres Y eeeewioOn, Oty PigMent. 2... ee asses sees res ennreecee 3 
IAL IOO TAM a a as eal patsaie = our * WARD A ayeclnanana”® 5 
Ea oe Bla Hs whos eRe cy ce eae ane eases RAL Oso REE es CONS ee ks 7 

1. GENERAL 


Red lead may be ordered in the form of dry pigment or of 
paste ground in pure raw linseed oil. Two grades of pigment, 
known as 85 and 95 per cent, may be ordered, and each contract 
shall state which grade is desired.’ 

Material shall be bought by net weight. 


1 Avoid storing red-lead paste in places of high temperature, as heat accelerates the tendency of this 
material to cake or harden. Purchasers are cautioned not to buy red lead in paste form unless it is to be 
used within three months after shipment by the contractor. 

63910°—23 


2 Circular of the Bureau of Standards 


(2) Dry Picment.—The pigment shall consist entirely of oxides 
of lead free from all adulterants and shall meet the following 
requirements: 


85 sonore: 95 per cent 


grade grade 
; Per cent Per cent 
True red lead (Pb,O,), not less than................--.-.--- 25 95 


Total impurities, including moisture, soluble matter, water— 

and matter insoluble in a mixture of nitric acid and 

hydrogen peroxide, not more than......-...-.-+-----+-++-- 1 1 
Remainder shall be lead monoxide (PbO). | 
Coarse particles: Retained on standard: No. 325 screen, not 

more than.........------ heer o-—se8¢ 4p - ete BEE ee 2.0 1.0 


When mixed with raw linseed oil, pss oils and liquid drier 
in the proportions’ | 


Dry red lead... 00.00 gates eae rains 8) 4s ae pounds.. 30 
Raw linseed oil: 2. 02... 25 cc hoe on es ce pint..." 3 
Turpentine WitLA SOL YS Bll dE Ae «Ree lee ae gills.. 2 
Liquid drier... 5.00.5 .0+ 25s e el ee ese cee) eee ee dos aon 


the resulting paint when brushed on a smooth vertical iron surface 
shall dry hard and elastic without running, streaking, or sagging. 

(b) PAstE.—The paste shall be made by thoroughly grinding the 
specified grade of dry pigment with pure raw or refined linseed oil. 

The paste, as shipped by the contractor, and for three months 
thereafter, shall not be caked in the container and shall readily 
break up in oil to form a smooth paint of brushing cae 
The paste shall have the following composition : 


Per cent 
Pigments. sccn0 vein sdk ev dines eee aco ae C5 oe ee ; 92 
Linseed olf, 9.30 \h0sssenes cheo tha Beare a! ani ee 6 
Moisture and other volatile matter. ...... t-s:-.ie70h7. sal venibees bas... 
Coarse particles and. skins (total residue left on No. 325, + baubre oteaq 
soreen);- ci o435- Jaspee - faoarpisee> el sp gee = 4 fepem: meny- oa) Fer GS des opercarsk 


When mixed with raw linseed oil, ‘turpentine, and liquid eo 
in the proportions 


Redilead: paste. wi tuoi hz esis ot dam bemaleaas 9am dtm mh 5 poling ede ee 20 ns sain 
Raw linseed oil............. 709" te hd Jeerde ivia ediepinesdr aitiaiig bat 
Turpentine. .... 0.65.2 .te.+ pup = eee ng ee gitis; Stee 


Red Lead, Dry and Paste 8 


the resulting paint when brushed on a smooth vertical iron surface 
shall dry hard and elastic without running, streaking, or sagging. 


2. SAMPLING 


It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1000 packages be taken as repre-— 
sentative of the whole. 

With the dry pigment, this package is to be opened by the 
inspector and a sample of not less than 5 pounds taken at random 
from the contents and sent to the laboratory for test. When 
requested, a duplicate sample may be taken from the same package 
and delivered to the seller, and the inspector may take a third 
sample to hold for test in case of dispute. 

With the paste, whenever possible, an original unopened con- 
tainer shall be sent to the laboratory, and when this is for any 
reason not done, the inspector shall determine by thoroughly 
testing with a paddle or spatula whether the material meets the 
requirement regarding not caking in the container (see 4 (a)). 
After assuring himself that the paste is not caked in the can, the 
inspector shall draw a sample of not:less than 5 pounds of the 
thoroughly mixed paste, place it in a clean dry metal or glass 
container, which must be filled with the sample, closed with a 
tight cover, sealed, marked, and sent to the laboratory for test 
with the inspector’s report on caking in container. 

Samples will, in general, be tested by the following methods, 
but the purchaser reserves the right to apply any additional 
tests, or use any available information to ascertain whether the 
material meets the specification. 


3. LABORATORY EXAMINATION, DRY PIGMENT 


(a) QUALITATIVE ANALYSIS.—Follow ordinary methods of 
qualitative analysis. The material should give a negative test 
for matter insoluble in a mixture of nitric acid and hydrogen 
peroxide, atid material other than oxides of lead. (If more than a 
faint cloud remains after treatment with nitric acid and hydrogen 
peroxide, it will be necessary to take a weighed sample and deter- 
mine the percentage of this insoluble matter.) Boil 2 g of the 
sample with 25 cc of 95 per cent ethyl alcohol, let settle, decant off 
the supernatant liquid, boil the residue with water, decant as 
before, and boil the residue with very dilute ammonia. If the 


4 Circular of the Bureau of Standards 


alcohol, water, or ammonia are colored, organic coloring matter is 
indicated, which is cause for rejection. 

(b) True Rep LeEap.—Weigh accurately 1 g of the Pa: into 
a 200 cc Erlenmeyer flask, add a few drops of distilled water, and 
rub the mixture to a smooth paste with a glass rod flattened on 
the end. Mix in a small beaker 30 g of pure crystallized sodium 
acetate, 2.4 g of pure potassium iodide, 10 cc of water, and 10 ce 
of 50 per cent acetic acid. Stir until all is liquid, warm gently, 
and, if necessary, add 2 to 3 cc more water. Cool to room tem- 
perature and pour into the flask containing the red lead. Rub 
with the glass rod until nearly all the red lead has been dissolved, 
add 30 cc of water containing 5 to 6 g of sodium acetate, and 
titrate at once with standard sodium thiosulphate solution, 
adding the latter rather slowly and keeping the liquid constantly 
in motion by whirling the flask. When the solution has become 
light yellow, rub any undissolved particles up with the rod until 
free iodine no longer forms, wash off the rod, and add the sodium 
thiosulphate solution until pale yellow. Add starch solution 
and titrate until colorless, add standard iodine solution until the 
blue color is just restored... From the amount of standard iodine 
solution used, calculate the correction to be applied to the thio- 
sulphate reading, and calculate true red lead Sindee: value 7 
thiosulphate X 2.7 = Pb,O, value). 

(c) WATER SOLUBLE MATTER.—Digest 10°g of the acini with 
200 ce of hot water on a steam bath for r hour; filter and wash 
with hot water until no residue is left on evaporating a few drops 
of the washings. Evaporate the filtrate to dryness in a weighed 
dish on a steam bath, heat for 30 minutes at 105 to 110° C, cool, 
and weigh. 

(d) Coarse ParticLes.—Dry in an oven at 105 to 110° Ca 
325 screen, cool, and weigh accurately. Weigh 25 g of the sample, 
dry at 100° C, transfer to a mortar, add 100 cc kerosene, thor- 
oughly mix by gentle pressure with a pestle to break up all lumps, 
wash with kerosene through the screen, breaking up all lumps, but 
not grinding. After washing with kerosene until all but the parti- 
cles which are too coarse to pass the screen have been washed 
through, wash all kerosene from the screen with ether or petro- 
leum ether, heat the screen for one boee at 105 to 110° hee cool, 
and weigh.’ oil Paatetredne edt 

2 For a general discussion of screen tests of pigments and data regarding many Slee on the iiatkel, 


see Circular No. 148 of the Educational Bureau, Scientific Section, Paint Manufacturers’ Association onthe 
United States. 


Red Lead, Dry and Paste 5 


(ce) RUNNING, STREAKING, OR SacGcInc.—Mix paint and apply 
as per specifications. About the smallest amount that can be 
conveniently made up will be 154 g dry red lead, 40 cc raw lin- 
seed oil, and 4 cc each of turpentine and liquid drier. 


4. LABORATORY EXAMINATION, PASTE 


(a) CAKING IN CONTAINER.—When an original package is re- 
ceived in the laboratory, it shall be weighed, opened, and stirred 
with a stiff spatula or paddle. The paste must be no more diffi- 
cult to break up and show no more caking than a normal good 
grade of red-lead paste. The paste shall finally be thoroughly 
mixed, removed from the container, the container wiped clean, 
and weighed. This weight subtracted from the weight of the 
original package gives the net weight of the contents. A portion 
of the thoroughly mixed paste shall be placed in a clean con- 
tainer and the portions for the remaining tests promptly weighed 
out. 

(b) Mrxinc witH LINSEED OIL, RUNNING, STREAKING, AND SAG- 
GING.—Mix as per specification to a paint, first using only the 
linseed oil and noting whether the paste breaks up readily and 
the resulting mixture is smooth. About the smallest amount that 
can bé conveniently made up will be 154 g red-lead paste, 36 cc 
raw linseed oil, and 4 cc each of turpentine and liquid drier. 

(c) MoIstURE AND OTHER VOLATILE MATTER.—Weigh accu- 
rately from 3 to 5 g of the paste into a tared flat-bottomed dish, 
about 8 cm in diameter, spreading the paste over the bottom. 
Heatiat 105 to 110° C for three hours, cool, and weigh. Calculate 
the loss in weight as percentage of moisture and other volatile 
matter. | 

(d) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 g 
of the paste into a weighed centrifuge tube. Add 20 to 30 cc 
of ‘‘extraction mixture’’ (see reagents), mix thoroughly with a 
glass rod, wash the rod with more of the extraction mixture, and 
add sufficient of the reagent to make a total of 60 cc in the tube. 
Place the tube in the container of a centrifuge, surround with 
water, and counterbalance the container of the opposite arm with 
a similar tube or a tube with water. Whirl at a moderate speed 
untilclear. . Decant the clear supernatant liquid. Repeat the ex- 
traction twice with 40 cc of extraction mixture, and once with 4o 
cc of ether. After drawing off the ether, set the tube in a beaker 
- of water at about 80° C or on top of a warm oven for 10 minutes, 


6 Cucular of the Bureau of Standards 


then in an oven at 105 to 110° C for 2 hours. Cool, weigh, and 
calculate percentage of pigment. 

(¢) EXAMINATION OF PIGMENT.—Grind the pigment from (d) 
to a fine powder, pass through a No. 80 screen to remove any 
‘‘skins,’’ preserve in a stoppered tube, and apply tests 3 (a), 
3 (6), and 3 (c). 

({) PREPARATION OF Fatrry Acips.—To about 25 g of the paste 
in a porcelain casserole, add 15 cc of aqueous sodium hydroxide 
(see reagents), and 75 ce of ethyl alcohol, mix and heat uncov- 
ered on a steam bath until saponification is complete (about one 
hour). Add 100 cc of water, boil, add sulphuric acid of specific 
gravity 1.2 (8 to 10 cc in excess), boil, stir, and transfer to a 
separatory funnel to which some water has been previously 
added. Draw off as much as possible of the acid aqueous layer 
and lead sulphate precipitate, wash once with water; then add 
50 ce water and 50 cc ether. Shake very gently with a whirling 
motion to dissolve the fatty acids in the ether, but not violently, 
so as to avoid forming an emulsion. Draw off the aqueous layer 
and wash the ether layer with one 15 cc portion of water and then 
with 5 cc portions of water until free from sulphuric acid. Then 
draw off the water layer completely. ‘Transfer the ether solution 
to a dry flask, add 25 to 50 g of anhydrous sodium sulphate. 
Stopper the flask and let stand with occasional shaking atia tem- 
perature below 25° C until the water is completely removed from 
the ether solution, which will be shown by the solution becoming 
perfectly clear above the solid sodium sulphate. Decant this clear 
solution (if necessary through a dry filter paper) into a dry1o0o cc 
Erlenmeyer flask. Pass a rapid current of dry air (Pass through 
CaCl, tower) into the mouth of the Erlenmeyer flask and heat to 
a temperature below 75° C on a dry hot plate until the ether is 
entirely driven off. ‘The fatty acids prepared as above wiribnie; be 
kept in a stoppered flask and examined at once. : 

Notr.—It is important to follow all of the details, since ether generally contains 
alcohol, and after washing with water always contains water. It is very difficult to 
remove water and alcohol by evaporation from fatty acids, but the washing of the 
ether solution and subsequent drying with anhydrous sodium sulphate removes 
both water and alcohol. Ether, in the absence of water and alcohol, is wood removed 
from fatty acids by gentle heat. 

(g) TEST FOR MINERAL O1L.—Place ro drops of the fait acid Ly) 
in a 50 cc test tube, add 5 cc of alcoholic soda (see reagents), boil 
vigorously for five minutes, add 4o ec of water, and mix; a cleat 


solution indicates that not more than traces of ‘unsaponifiable — 


ked Lead, Dry and Paste 7 


matter are present. If the solution is not clear, the oil is not pure 
linseed oil. 

(h) lopInE NuMBER oF Farry Acips.—Place a small quantity 
of the fatty acids (/) in a small weighing burette or beaker. Weigh 
accurately. ‘Transfer by dropping about 0.15 g (0.10 to 0.20 g) to 
a 500 cc bottle having a well-ground glass stopper, or an Erlen- 


meyer flask having a specially flanged neck for the iodine test. 


Reweigh the burette or beaker and determine the amount of sam- 
ple used. Add 1tocc of chloroform. Whirl the bottle to dissolve 
the sample. Add 10 ce of chloroform to two empty bottles like 
that. used for sample. Add to each bottle 25 ce of the Hanus 
solution (see reagents) and let stand with occasional shaking for 
one-half hour. Add 1o,cc of the 15 per cent potassium iodide 
solution and too ce of water, and titrate with standard sodium 


thiosulphate, using starch as indicator. The titrations on the two 


blank tests should agree within 0.1 cc. From the difference be- 
tween the average of the biank titrations and the titration on the 
sample and the iodine value of the thiosulphate solution, calculate 
the iodine number of the sample tested. (Iodine number is centi- 
grams of iodine to 1 g of sample.) If the iodine number is less 
than 170, the oil does not meet the specification. 

(1) Coarse PARTICLES AND SKINS.—Weigh an amount of paste 
containing 25 g of pigment (see 4 (d)), add 200 cc of kerosene, and 
wash through a No. 325 screen as in 3 (d). 


5. REAGENTS 


(a) EXTRACTION MIxTURE.— 
to volumes ether (ethyl ether). 
6 volumes benzol. 
4 volumes methyl alcohol. 
I volume acetone. 
(6) AguEous Soprum Hyprox1pE.—Dissolve too g of sodium 
hydroxide in distilled water and dilute to 300 cc. 
(c) STANDARD Soprum ‘THIOSULPHATE SOLUTION.—Dissolve 


_ pure sodium thiosulphate in distilled water that has been well 


boiled to free it from carbon dioxide, in the proportion of 24.83 g 
of crystallized sodium thiosulphate to 1000 cc of the solution. It 
is best to let this solution stand for about two weeks before 
standardizing. Standardize with pure resublimed iodine. (See 
Treadwell-Hall, Analytical Chemistry, vol. 2, 3d ed., p. 646.) 
This solution will be approximately decinormal and it is best to 


8 Circular of the Bureau of Standards 


leave it as it is after determining its exact iodine value, rathér than 
to attempt to adjust it to exactly decinormal. Preserve in a stock 
bottle provided with a guard tube filled with solda lime. 

(d) STARCH SOLUTION.—Stir up 2 to 3 g of potato starch or 5° g 
of soluble starch with roo cc of 1 per cent salicylic acid solution, 
add 300 to 400 ce of boiling water, and boil the mixture until vai 
starch is practically dissolved, then dilute to r liter. 

(¢) STANDARD IODINE SOLUTION.—Dissolve 13 ¢ of veined 
iodine and 18 g of pure potassium iodide (free from iodates) in 50 
ce of distilled water, and dilute to tooo ee. Determine its exact 
value by titrating with the standard sodium thiosulphate solution. 

(7) Porassrum IopIpE SOLUTION.—Dissolve 150 g of potassium 
iodide, free from iodate, in distilled water and dilute to 1000 cc. 

(9) HANus SoLuTIon.—Dissolve 13.2 g of iodine in 1000 ce of 
99.5 per cent glacial acetic acid, which will not reduce chromic 
acid. Add enough bromine to double the halogen content, deter- 
mined by titration (3 cc of bromine is about the proper amount). 
The iodine may be dissolved by the aid of heat, but the solution 
should be cold when the bromine is added. | 

(h) ALCOHOLIC SoprumM HyproxiIpE SoLurIon. anihiedive pure 
sodium hydroxide in 95 per cent ethyl alcohol in the proportion 
of about 22 g per roooce. Let stand in a stoppered bottle. De- 
cant the clear liquid into another bottle and keep well stoppered. 
This solution should be colorless or only slightly yellow when 
used, and it will keep colorless longer if the alcohol is previously 
treated with sodium hydroxide (about 80 g to 1000 aes kept at 
about 50° C for 15 days, and then distilled. 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 


5CENTS PER COPY 
V 


DEPARTMENT OF COMMERCE 


BUREAU OF STANDARDS 
S. W. STRATTON, Director 


CIRCULAR OF THE BUREAU OF STANDARDS 
No. 91 


[2d edition, issued June 21, 1922] . et 
UNITED STATES GOVERNMENT SPECIFICATION FOR 
3 OCHER, DRY AND PASTE 


FEDERAL SPECIFICATIONS BOARD 
STANDARD SPECIFICATION NO. 12 


This Specification was officially adopted by the Federal Specifications Board 
on February 3, 1922, for the use of the Departments and Independent Establish- 
ments of the Government in the purchase of materials covered by it. 


CONTENTS 
: . Page 
Ea ils oh erie ard ab tunchams I 
ee re dass pu nne ccd nswk vplav ages {ERE 2 
3 Laboratory @xamination of dry pigment. 2. 2 A et 2 
4a;leaboratory examination of: paste, :ac)ay: .celad.ace. 1. al Olinet.&. be 4 
a oh FE 6 a fit it Rik i es 7 
1. GENERAL 


Ocher may be required in the form of dry pigment or paste 
ground in linseed oil; it shall be prepared in accordance with the 
most improved methods. Grinding in oil shall be thorough and 
the vehicle shail be pure raw linseed oil. 

The material shall be bought by net weight. 

“ (a) Dry PicmentT.—The pigment shall be a hydrated oxide of 
iron permeating a siliceous base, and shall be free from added 
impurities. It shall conform to the following requirements: 

Color—Color Strength—T one.—Equal to sample mutually agreed 
on by buyer and seller. 


Maximum |} Minimum 


. Percent | Percent 
Coarse particles: Retained on standard No, 325 screen... --...-..----------+-+++- 130 


UN rok ay. snip in AM wh xn do yb os oink ice eh singe ake <he cag aaes AeA pie ce etna aan 17 
OE a SR Oh LL BB LR ah alin a es fae rete Pickin eis o lanawstaenwa 4 
Ua ehromarern (cei) b opoe ba 4 5- <p tace Chl.) «SEP eee SSID... SAIS SP TT. None) {ii52). Jc ok 
a a io nce ni i i ce hae a Se eh ne i i eed None, |..5.\-.-t.e0s 


109839°-—22 


2 Circular of the Bureau of Standards 


(6) PasteE.—Ocher in paste form shall consist of: 


Maximum | Minimum 


Per cent Per cent 


Pigment.........--.. Bee er ita tres. ar ey OE ASE REST <3. oT -eey. eek Wire 71 69 
Binseed. Off. oo. cee ecb n cua lak ceewe oabeeb oe euwalnce chats Pd eEe cee 31 29 
Molsture and volatile matter... 1. ..eul deus ss op dus gl abn cuake~ bat eee O.8 jose. ue eee 
Coarse particles and “‘skins’’ (total residue left on No. 325 screen) based on pig- 

111, | See RGR CAMs we rts gh a beh liners, created apne acpntnne. he a SiS iogeeeeearerk 


NotE.—Deliveries will, in general, be sampled and tested by the following methods, but the purchaser 
reserves the right to use any additional available information to ascertain whether the material meets the 
specification. 


2. SAMPLING 


It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1000 pag age* shall be taken 
as representative of the whole. 

With the dry pigment, this package. shall os opened by the 
inspector and a sample of not less than 5 pounds taken at random 
from the contents and sent to the laboratory for test. 

With the paste, whenever possible, an original unopened con- 
tainer shall be sent to the laboratory; and when this is for any 
reason not done, the inspector shall determine, by thorough test- 
ing with a paddle or spatula, whether the material meets the 
requirement regarding not caking in the container. (See 4 (a).) 
He shall then thoroughly mix the contents of the container and 
draw a sample of not less than 5 pounds. This sample shall be 
placed in a clean, dry, metal or glass container which it must 
nearly fill. The container shall be closed with a tight cover, sealed, 
marked, and sent to the laboratory for test with the inspector: s 
report on caking. 

When requested, a duplicate sample may be aii from the 
same package and delivered to the seller, and the inspector. may 
take a third sample to hold for test in case of Hispute. 


3. LABORATORY EXAMINATION OF DRY PIGMENT 


(a) CoLOR AND TONE.—Weigh 1 g each of the color and esta: 
ard and rub up separately on a glass plate or stone slab, using 
the same amount of bleached linseed oil in each case. Place por- 
tions of each side by side on a clean strip of*glass, turn the glass 
over and compare the colors. Rubbing up (mixing with oil) is 
best done with a muller, and should be such that no lumps remain’ 
and that the consistency of both paste portions is ey same. 


Specification for Ocher, Dry and Paste 3 


Smear (with the finger) portions of the pastes on a clear glass 
strip and compare the tone by transmitted light. 

(6) CoLoR STRENGTH.—Weigh accurately 0.05 g each of the 
color and standard and two portions of 1 g each of the zinc oxide. 
Add the color to one of the portions of zinc oxide and the standard 
to the other and rub up separately in linseed oil until on spreading - 
out no dark streaks are visible. Place the color and standard tints 
side by side on a clean glass strip, turn the strip over and compare. 

(c) CoARSE. PARTICLES."—Dry in an oven at 105 to 110° C a 
325 screen, cool and weigh accurately. Weigh ro g of the sample; 
dry at 100° C, transfer to a mortar, add'100 cc kerosene, thoroughly 
mix by gentle pressure with a pestle to break up all lumps; wash 
with kerosene through the screen, breaking up all lumps but not 
grinding. After washing with kerosene until all but the particles 
which are too coarse to pass the screen have been washed through, 
wash all kerosene from the screen with ether or petroleum ether, 
heat the screen for one hour at 105 to 110° C, cool and weigh. 

(d) Morsture.—Place 1 g of the sample in a wide-mouth, short 
weighing tube provided with a glass stopper, and weigh accu- 
rately. Heat with stopper removed for two hours at a tempera- 
ture between 100 and 105° C. Insert stopper, cool and weigh. 
Calculate loss in weight as moisture. 

(e) ORGANIC COLORING MATTER (A. S. T. M. “Standards,” 1918, 
_ p. 656).—Test the pigment successively with hot water, 95 per 
cent alcohol, alcoholic sodium hydroxide and acetic acid. Chloro- 
form, sodium hydroxide, sulphuric acid, hydrochloric acid-stan- 
nous chloride solution, and other reagents may be tried. The 
solutions should remain colorless: The presence of an organic 
color may often be detected by the characteristic odor given off 
on ignition. | 

({) Toray IRon Ox1pDE.—Ignite 1 g of the sample in a porcelain 
crucible at a dull red heat to destroy organic matter. Transfer to 
a 500 cc Erlenmeyer flask and add 20 cc of 1 : 1 hydrochloric acid. 
Digest just short of boiling until no dark specks can be seen in the 
insoluble residue. When the residue is light in color, the solution 
of iron may be considered complete. Dilute to 100 cc and without 
filtering, add 3 g of granulated zinc; put a funnel in the neck of 
the flask and heat when the action slackens; if basic iron salts 
separate out, add a few drops of hydrochloric acid. When the 

1 For a general discussion of screen tests of pigments and data regarding many pigments on the 


market, see Circular No, 148 of the Educational Bureau, Scientific Section, Paint Manufacturers’ Associa- 
tion of the U. S. . 


4 Circular of the Bureau of Standards 


reduction is complete, add 30 ce of sulphuric acid (1:2) and as» 
soon as the residual zinc is dissolved, wash down the funnel and 
neck of the flask with a fine jet of water. Now add 200 cc of cool 
water and 30 ce of titrating solution (see reagents) and titrate 
with standard potassium permanganate. Rum a blank.on the 
zinc and calculate ferric oxide (Fe,O,).. Any other aceurate 
method for determining iron may be used at the option of the 
analyst. | 

(g) Test For LEAD AND CALCIUM BY THE wast Quake 
Metuops.—If calcium is present in appreciable amount, determine 
it as follows: Ignite 2.5 gin a porcelain crucible at'a dull red heat 
to destroy organic matter. ‘Transfer to a 500 cc graduated flask; 
add 100 cc of 1 : 1 hydrochloric acid. Digest just short of boiling 
until no dark specks:'can be seen in the insoluble residue; add 
ammonia in slight excess and about 2 cc of hydrogen peroxide 
solution; cool, dilute to 500 cc; mix thoroughly, filter through a 
dry paper. Take roo cc of the filtrate (corresponding to 0.5 g 
of sample), heat to boiling, add a few drops of ammonia and an 
excess of a hot saturated ammonium oxalate solution. Continue 
boiling until the precipitate becomes granular; let stand about 
30 minutes, filter, wash with hot water until free from ammonium 
oxalate. Pierce the apex of the filter with a stirring rod and 
wash the precipitate into the beaker with hot water; pour warm 
dilute sulphuric acid (1 : 4) through the paper and wash a few 
times. Add about 30 cc of sulphuric acid (1 : 4), dilute to about 
250 cc with hot water and titrate at once with standard potas- 
sium permanganate solution (the solution should not be below 
60° C when the end point is reached). Calculate to CaO. (The 
Fe value of KMnO,x0.502=CaO value.) 


4, LABORATORY EXAMINATION OF PASTE 


(a) CAKING IN CONTAINER.—When an original package is 
received in the laboratory it shall be weighed, opened, and stirred 
with a stiff spatula or paddle. The paste must be no more diffi- 
cult to break up and show no more caking than a normal good 
grade of ocher paste. The paste shall be finally thoroughly mixed, 
removed. from the container, and the container wiped clean’ and 
weighed. ‘This weight subtracted from the weight of the original 
package gives the net weight of the contents. A portion of the 
thoroughly mixed paste shall be placed in a clean container and 
portions for the remaining tests promptly weighed out from it. _ 


Specificaiion for Ocher, Dry aud Paste 5 


(6) MrxiInc with O11, or THINNING.—Add sufficient linseed 
oil to 100 g of the sample to make a liquid paint of proper con- 
sistency for application with a brush, noting the amount of oil 
necessary. Note the smoothness with which the paint works 
under the brush. 

(c) MoistuRE AND OTHER VOLATILE Matrer.—Weigh accu- 
rately from 3 to 5 g of the paste into a tared flat-bottomed dish 
about 8 cm in diameter, spreading the paste over the bottom. 
Heat at 105 to 110° C for three hours, cool, and weigh. Calculate 
loss in weight as percentage of moisture and volatile matter. 

(d) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 g 
of the paste into a weighed centrifuge tube. Add 20 to 30 cc of 
“extraction mixture’’ (see Reagents), mix thoroughly with a glass 
rod, wash the rod with more of the extraction mixture, and add 
sufficient of the reagent to make a total of 60 cc in the tube. 
Place the tube in the container of a centrifuge, surround with 
water, and counterbalance the container of the opposite arm 
with a similar tube or a tube with water. Whirl at a moderate 
speed until well settled. Decant ‘the clear supernatant liquid. 
Repeat the extraction twice with 40 cc of extraction mixture and 
once with 40 cc of ether. After drawing off the ether, set the 
tube in a beaker of water at about 80° C or on top of a warm 
oven for 10 minutes, then in an oven at 105 to 110° € for two 
hours. Cool, weigh, and calculate the percentage of pigment. 

(e) EXAMINATION OF THE PIGMENT.—Grind the pigment from 
(d) to a fine powder, pass through an 80-mesh screen to remove 
any skins, preserve in a stoppered bottle, and examine as under 
3(e), 3(/), and 3(9). 

(f) Coton, ToNE, AND COLOR STRENGTH.—Extract the pig- 
ment from the vehicle with extraction mixture as in 4(d), except 
that it is not necessary to accurately. weigh the amount taken, 
and after washing with ether, dry in a vacuum at a temperaturé 
not above 70° C. Grind this extracted pigment fine enough to 
pass a No. 80 screen to remove skins, and test as under 3(a) 
and 3(b). 

_(g) COARSE PARTICLES AND, SKINS.—Weigh an amount of paste 
containing 10 g of pigment (see 4(d)), add 200 cc of kerosene, 
and wash through a No. 325 screen as in 3(c). 

(h) PREPARATION OF Farry Acips.—To about 25 g of the paste 
in a porcelain casserole, add 15 cc of aqueous sodium hydroxide 
(see reagents) and 75 cc of ethyl alcohol, mix and heat uncovered 


6 Circular: of the Bureau of Standards 


on a steam bath until saponification is complete (about one 
hour). Add 100 ce of water, boil, add sulphuric acid of specific 
gravity 1.2 (8 to ro ce in excess), boil, stir, and transfer to a 
separatory funnel to which some water has been previously 
added. Draw off as much as possible of the acid aqueous layer 
and insoluble mineral matter, wash once with water, then add 
50 cc of water and 50 cc of ether. Shake very gently with a 
whirling motion to dissolve the fatty acids in the ether, but 
not so violently as to form an emulsion: Draw off the aqueous 
layer and wash the ether layer with one 15 ce portion of water . 
and then with 5 cc portions of water until free from sulphuric 
acid. Then draw off the water layer completely. Transfer the 
ether solution to a dry flask and add 25 to 50 g anhydrous 
sodium sulphate. Stopper the flask and let stand with occasional 
shaking at a temperature below 25° C until the water is com- 
pletely removed from the ether solution, which will be shown by 
the solution becoming perfectly clear above the solid sodium 
sulphate. Decant this clear solution, if necessary, through a dry 
filter paper, into a dry 100 cc Erlenmeyer flask. Pass a rapid 
current of dry air (pass through a CaCl, tower) into the mouth of 
the Erlenmeyer flask and heat to a temperature below 75° C on 
a dry hot plate until the ether is entirely driven off: The fatty 
acids prepared as above should be kept in a stoppered flask ue 
examined at once. 

Note. It is important to follow all of the details, since ether generally contains 
alcohol and, after washing with water, always contains water. It is very difficult to 
remove water and alcohol by evaporation from fatty acids, but the washing of the 
ether solution and subsequent drying with anhydrous sodium sulphate removes both 
water and alcohol. Ether, ia the absence of water and alcohol, is easily’ removed 
from fatty acids by gentle heat. 

(i) THST FoR MINERAL OIL AND OTHER UNSAPONIFIABLE MAT- 
TER.—Place to drops of the fatty acids (h) in a 50 cc test tube, 
add 5 cc of alcoholic soda (see Reagents), boil vigorously for 5 
minutes, add 40 cc of water and mix; a clear solution indicates 
than not more than traces of unsaponifiable matter are present. 
If the solution is not clear, the oil is not pure linseed oil. 

(7) loprine NuMBER OF Farry Actps.—Place a small quantity 
of fatty acids (k) in a small weighing burette or beaker. Weigh 
accurately. ‘Transfer, by dropping, about 0.15 g (0.10 to 0.20 g) 
to a 500 cc bottle having a well-ground glass stopper, or an Erlen- 
meyer flask having a specially flanged neck for the iodine test. 
Reweigh the burette or beaker and determine amount of sample 


Specification for Ocher, Dry and Paste ‘| 


used.. Add 10 cc of chloroform. Whirl the bottle to dissolve 
the sample. Add 10 ce of chloroform to each of two empty 
bottles like that used for the sample. Add to each bottle 25 cc 
of the Hanus solution (see Reagents) and let stand, with occa- 
sional shaking, for one-half hour. Add 10 ce of the 15 per cent 
potassium iodide solution and 100 ce of water, and titrate with | 
standard sodium thiosulphate using starch as indicator. The 
titrations on the two blank tests should agree within o.1 cc. 
From the difference between the average of the blank titrations 
and the titration on the sample, and the iodine value of the thio- 
sulphate solution calculate the iodine number of the sample tested. 
(Jodine number is centigrams of iodine to 1. g of sample.) If the 
iodine number is less than 170, the oil does not meet the 
specification. 
5. REAGENTS 


(a) EXTRACTION MrxTuRE.— 
10 volumes ether (ethyl ether). 
6 volumes benzol. 
4 volumes methyl alcohol. 
1 volume acetone. 
(6) AguEOous Soprum HyproxipE.—Dissolve 100 g of sodium 
hydroxide in distilled water and dilute to 300 cc. 
(c) SYANDARD Soprum ‘THIOSULPATE SoLUTION. — Dissolve 
. pure sodium thiosulphate in distilled water (that has been well 
boiled to free it from carbon dioxide) in the proportion of 24.83 g 
crystallized sodium thiosulphate to 1000 cc of the solution. It is 
best to let this solution stand for about two weeks before standard- 
izing. Standardize with pure resublimed iodine. (See Treadwell- 
Hall, Analytical Chemistry, vol. 2, 3d ed., p. 646.) This solution 
will be approximately decinormal, and it is best to leave it as it is 
after determining its exact iodine value, rather than to attempt 
to adjust it to exactly decinormal. Preserve in a stock bottle 
provided with a guard tube filled with soda lime. | 
~(d) SrarcH SOLUTION.—Stir up 2 to 3 g of potato starch or 
5 g of soluble starch with 100 cc of 1 per cent salicylic acid solution, 
add 300 to 400 cc boiling water, and boil the mixture until the 
starch is practically dissolved, then dilute to 1 liter. 
(ec) Potassium IoprpE SoLwutTron.—Dissolve 150 g of potassium 
iodide free from iodate in distilled water and dilute to 1000 cc. 
(f) Hanus SoLutTion.—Dissolve 13.2 g of iodine in 1000 cc of 
99.5 per cent glacial acetic acid, which will not reduce chromic 


8 CIRCULAR OF THE BUREAU OF STANDARDS 


(b) Cotor.—Follow the procedure outlined in 3 (0). 

(c) Wricut pER GaLton.—Weigh a clean, dry, 100 cc graduated 
flask. Fill to the mark with the thoroughly mixed paint and weigh 
again. The increase in weight expressed in grams, divided by 100, 
gives the specific gravity, which multiplied by 8.33 gives the weight 
in pounds per gallon. 

(2) BrusHinc PROPERTIES AND Time oF Dryine.—Brush the 
well-mixed paint on a suitable panel, which may be ground glass, 
steel, or well-filled wood. Note whether the paint works satis- 
factorily under the brush. Place the panel in a vertical position 
in a well-ventilated room and let stand for 18 hours. The paint 
shall be dry, smooth, and free from streaks. Flow a portion of the 
paint on a clean glass plate. Let dry in a’nearly vertical position 
at room temperature (65 to 100° F.). The film shall show no streak- 
ing or separation within a distance of 4 inches from the top. 

(e) Watrer.—Mix 100 g of the paint in a 500 cc short-neck glass 
flask } with 75 ec of toluol (free from water). Connect with the 
distilling trap and condenser, and heat so that the condensed dis- 
tillate falls from the end of the condenser at the rate of from two to 
five drops per second. Continue the distillation at the specified 
rate until no water is visible on any part of the apparatus except at 
the bottom of the trap. This operation usually requires less than 
an hour. A persistent ring of condensed water in the condenser 
tube should be removed by increasing the rate of distillation for a 
few minutes. The number of cubic centimeters of condensed water 
measured in the trap at room temperature is the percentage of 
water in the paint. 

(f) Vouatite TxHiInner.—Follow the procedure outlined in 2 (e). 
Correct the result for any water found (see 4 (e)) and ener the 
remainder as volatile thinner. 

(9) PerceNTAGE oF PiamMEeNT.—Follow the procedure outlined 
in 2 (f). 

(h) Testinc NonvoLaTILE VeutcLte.—Follow the preted site out- 
lined in 2 (g), 2 (A), and 2 (i), except that in the preparation of the 
fatty acids the mixture of paint and alkali is heated on the steam 
bath until all volatile thinner is driven off. | 

(1) CoaRsE PARTICLES AND SKINS. oa the prokeuint out- 
lined in 2 (7). 

(j) Testing Picment.—Follow the ihn dutlfineed in 3 (a) to 
4 (d), inclusive. 

1 The apparatus for determining water is that described in ‘‘Standard method of test for water in petro- 


leum products and other bituminous materials,” Serial Designation D-95-24, A. 8S. T. M. Standards, 
1924, p. 901, and Figure 1 (6) and (c), p. 902. 


Se 


SPECIFICATION FOR IRON OXIDE AND IRON HYDROXIDE 9 


5. REAGENTS 


(a) Extraction MixtTurE.— 
10 volumes ether (ethyl ether). 
‘6 volumes benzol. 
4 volumes methyl! alcohol. 
1 volume acetone. 

(6) Aqurous Sopium Hyproxipe.—Dissolve 100 g of sodium 
hydroxide in distilled water and dilute to 300 cc. 

(c) Sranparp Sopium THIosuLPHATE SoLuTION.—Dissolve pure 
sodium thiosulphate in distilled water (that has been well boiled 
to free it from carbon dioxide) in the proportion of 24.83 ¢ of crys- 
tallized sodium thiosulphate to 1,000 cc of the solution. It is best 
to let this solution stand for about two weeks before standardizing. 
Standardize with pure resublimed iodine. (See Treadwell-Hall, 
Analytical Chemistry, vol. 2, 6th ed., p. 551.) This solution will be 
approximately decinormal, and it is best to leave it as it is aiter 
determining its exact iodine value, rather than to attempt to adjust 
it to exactly decinormal. Preserve in a stock bottle provided with a, | 
guard tube filled with soda lime. 

(d) Starcn SoLvutTion.—Stir up 2 to 3 g of potato starch or 5 g 
of soluble starch with 100 cc of 1 per cent salicylic acid solution, 
add 300 to 400 cc boiling water, and boil the mixture until the starch | 
is practically dissolved, then dilute to 1 liter. 

(ec) Porasstum lopipr Sotution.—Dissolve 150 g of idfasslum 
iodide free from iodate in distilled water and dilute to 1,000 ce. 

(f) Wiss Sotution.—The preparation of the iodine tidhobHiWvide 
solution presents no great difficulty, but it should be done with care 
and accuracy in order to obtain satisfactory results. There shall be 
in the solution no sensible excess either of iodine or more particularly 
of chlorine.over that required to form the monochloride. This con- 
dition is most satisfactorily attained by dissolving in the whole of 
the acetic acid to be used the requisite quantity of iodine, using 
gentle heat to assist the solution, if it is found necessary. Dissolve 
iodine in glacial acetic acid that has a melting point of 14.7 to 15° C. 
and is free from reducing impurities in the proportion so that 13 ¢ 
of iodine will be present in 1,000 cc of solution. Set aside a small 
portion of this solution while pure, and pass dry chlorine into the 
remainder until the halogen content of the solution is doubled. 
Ordinarily it will be found that by passing the chlorine into the 
main part of the solution until the characteristic color of free iodine 
has just been discharged, there will be a slight excess of chlorine 
which is corrected by the addition of the requisite amount of the 
unchlorinated portion until all free chlorine has been destroyed. A 
slight excess of iodine does little or no harm, but excess of chlorine 
must be avoided. 


10 CIRCULAR OF THE BUREAU OF STANDARDS | 


(g) Auconotic Soprum Hyproxipr Soxution.—Dissolve pure 
sodium hydroxide in 95 per cent ethyl alcohol in the proportion 
of about 22 g per 1,000 cc, Let stand in a stoppered bottle. Decant 
the clear liquid into another bottle and keep well stoppered. This 
solution should be colorless or only slightly yellow when used, and 
it will keep colorless longer if the alcohol is previously treated with 
sodium hydroxide (about 80 g to 1,000 cc), kept at about 50° C. for 
15 days, and then distilled. : 

(h) Stanparp Potassium DicHromaTE SoLution.—Dissolve 4.903 
g of pure, dry, crystallized potassium dichromate in water and 
dilute to 1,000 ce (1 cc=0.008 g Fe,0;). Determine its exact iron 
value with Bureau of Standards Standard Sample No. 27a, Sibley 
Iron Ore. 

(1) PHospHoric Actp Mrixture.—Mix 150 cc of sulphuric acid 
(specific gravity 1.84) with 150 ce of phosphoric acid (specific gravity 
1.7), and dilute the mixture with water to 1,000 ce. ; 

(7) DipHenyLaminE INpIcator.—Dissolve 1 g of diphenylamine 
in 100 cc of concentrated sulphuric acid. Use three drops of the 


* solution as indicator. 


(k) Stannous CuLoripE So.ution.—Dissolve 50 g of the crystal- 
lized salt (SnCl,.2H,O) in 300 ce of concentrated hydrochloric acid 
and dilute with water to 500 cc. Keep the clear solution in a 
tightly stoppered bottle containing some metallic tin. 

(1) Mercuric Cuioripe Souution.—A saturated solution of 
HgCl, (60 to 100 g per liter). 

(m) Potassium FErricyanipe SoLution.—A 1 per cent solution 
is satisfactory. Dissolve a piece half as big as a small pea in 50 cc 
of water. This solution must be made fresh when wanted, because 
it does not keep. 


VII. PACKING AND MARKING OF SHIPMENTS 


Shall be in accordance with commercial practice unless ee 
specified. 
VIII. NOTES 


This specification applies to iron-oxide and iron-hydroxide paints 
of red and brown colors. The paint may be ordered in the form of 
either semipaste paint or ready-mixed paint. The semipaste may 
be purchased by net weight or by volume. The ready-mixed paint 
should be purchased by volume (231 cubic inches to the gallon). 

For formulas and methods of using this material and information 
regarding the use of other specification paint materials see Bureau 
of Standards Technologic Paper No. 274, entitled “Use of United 
States Government Specification Paints and Paint Materials.” 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT 
5 CENTS PER COPY 


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Specification 


No. 14b 


DEPARTMENT OF COMMERCE 


BUREAU OF STANDARDS 
GEORGE K. BURGESS, Director 


CIRCULAR OF THE BUREAU OF STANDARDS, No. 94 


[3d-edition, issued April 29, 1927] 


UNITED STATES GOVERNMENT MASTER SPECIFICATIONS 
FOR PAINT, BLACK, SEMIPASTE AND READY MIXED 


FEDERAL SPECIFICATIONS BOARD SPECIFICATION NO. 14b 
[Revised September 2, 1925] 


This specification was officially promulgated by the Federal Specifications 
Board on February 3, 1922, for the use of the departments and independent 
establishments of the Government in the purchase of black paint, semipaste 
and ready mixed. 


[The date on which the technical requirements of this revision of this specification became mandatory 
for all departments and independent establishments of the Government was September 2, 1925. The 
changes included in this revision were authorized by the Federal Specifications Board and promulgated ina 
circular letter on above revision date. 


CONTENTS 


VI. Methods for sampling and testing. ______2 


VU. Packing and marking of shipments_.-__.____2__. CLUES SMT pi 
BNO on cr egah et eee ee ee ee 
43230°—27 


BOON SOPWWwWHDY DYDD wd 


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CIRCULAR OF THE BUREAU OF STANDARDS 
I. GENERAL SPECIFICATIONS 
There are no general specifications applicable to this specification. 
Il. TYPES 


Black paint shall be of the following types: Semipaste in linseed 
oil and ready-mixed. 


Ill. MATERIAL AND WORKMANSHIP 
See detail requirements. 
IV. GENERAL REQUIREMENTS 
See detail requirements. 
V. DETAIL REQUIREMENTS 


1. PIGMENT 


The pigment in both semipaste and ready-mixed paints shall 
consist of carbon, lead oxide, insoluble mineral material, and, at the 
option of the manufacturer, oxide of iron. The pigment shall show 
on analysis not less than 20 per cent of carbon and not less than 5 
per cent of lead oxide calculated as Pb;0,. The total of the lead oxide, 


iron oxide, insoluble mineral material, and loss on ignition shall be not 


less than 90 per cent. 
2. LIQUID 


The liquid in semipaste paint shall be entirely linseed oil; in ready- 
mixed paint it shall contain not less than 80 per cent linseed oil, the 
balance to be combined drier and thinner. The thinner shall. Ds 


turpentine, volatile mineral spirits, or a mixture thereof. 
3. SEMIPASTE 


Semipaste shall be made by thoroughly grinding the pigment with 
linseed oil. 

The semipaste as received and three months thereafter shall be 
not caked in the container and shall break up readily in linseed 
oil to form a smooth paint of brushing consistency. It shall mix 
readily with linseed oil, turpentine, or volatile mineral spirits, or 
any combination of these substances, in all proportions. without 
curdling. The color and hiding power when specified shall be equal 
to that of a sample mutually agreed upon by buyer and seller. 
The weight per gallon shall be not less than 10 pounds. ‘The paste 
shall consist of: sist 


) 
| 
i 
: 
| 
q 


es ee 


ee ee ee ee ee ee atl 


i ee a ee 


_ SPECIFICATION FOR BLACK PAINT... . 3 


Maximum } Minimum 
—_— 
Per cent °| Per cent 
ee eo BES SS ae Se ae i Se a, 52 48 
Linseed oil__.2__- oh Sar ee ee SCS AR CR i Me Re Lae 52 . 48 


4. READY-MIXED PAINT 


Ready-mixed paint shall be well ground, shall not settle badly or 
cake in the container, shall be readily broken up with a paddle to a 
smooth uniform paint of good brushing consistency, and shall dry 
within 18 hours to a full oil gloss, without streaking, running, or 
sagging. The color and hiding power when specified shall be equal 
to those of a sample mutually agreed upon by buyer and seller. 
The weight per gallon shall be not less than 9 pounds. The paint 
shall consist of: 


| Maximum |} Minimum 
<==>"Senee ge tesenemanmne emer ape ee cn Ee ae hee es 


Per cent Per cent 


ee ee ee 32 28 
aig (containing at least 80 per cent linseed LN ae Se SE ES BMY 8 2 72 : 68 
ee eR et a Re abana one gee mma cdennse waraint hs. Rs Be nahn ee 
Coarse particles and ‘“‘skins” (total residue retained on No. 325 screen based on 
pigment) csn.3 25... LO eR ESSE EAS Se a Ss ee ERTS Tag 4 ed Al hI ere Soe 
er Feit eg 


VI. METHODS FOR SAMPLING AND TESTING 


Deliveries will, in general, be sampled and tested by the following 
methods, but the purchaser reserves the right to use any additional 
available information to ascertain whether the material meets the specifi- 
cation. 

1. SAMPLING 


It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1,000 packages shall be taken as 
representative of the whole. Whenever possible an original unopened 
container shall be sent to the laboratory, and when this is for any 
reason not done, the inspector shall determine by thorough testing 
with a paddle or spatula whether the material meets the require- 
ments regarding caking in the container. He shall then thoroughly 
mix the contents of the container and draw a sample of not less than 
5 pounds of the thoroughly mixed paint, place it in a clean, dry metal 
or glass container, which it shall nearly fill. The container shall be 
closed with a tight cover, sealed, marked, and sent to the laboratory 
for test with the inspector’s report on caking. 

When requested, a duplicate sample may be taken from the same 
package and delivered to the seller, and the Inspector may take a 
third sample to hold for test in case of dispute. 


4 CIRCULAR OF THE BUREAU OF STANDARDS 
2. LABORATORY EXAMINATION—SEMIPASTE 


(a) Caxine 1n ConTatner.—When an original package is received 
in the laboratory, it shall be weighed, opened, and stirred with a stiff 
spatula or paddle. The paste must be no more difficult to break up 
than a normal good grade of semipaste paint. The semipaste shall 
finally be thoroughly mixed, removed from the contaimer, and the 
container wiped clean and weighed. This weight subtracted from 
the weight of the original package gives the net weight o the con- 
tents. A portion of thoroughly mixed semipaste shall be placed in a 
clean container and the portions for the remaining tests promptly 
weighed out. cod Ri eteaes 

(b) Cotor.—Place some of the paint on a clean clear glass plate. 
Place some of the standard agreed upon beside the sample on the 
plate, turn the glass over, and compare the colors. . | 

(c) We1cut per GaLton.—From the weight of a known volume 
of the paste calculate the specific gravity, which multiplied by 8.33 
vives the weight in pounds per gallon. Any suitable contaimer of 
known volume may be used for the purpose, but a short cylinder 
of heavy glass with rounded bottom about 75 mm high and having 
a capacity of from 125 to 175 ce (a glass cap to keep dust from 
reagent bottle stopper) is a convenient apparatus for the purpose. 
The capacity of this vessel is determined to within 1 cc. The paste 
is packed into it until completely full, the top leveled off smooth 
with a spatula, and weighed to 40:5 g. Subtract the weight of the 
empty container and divide the remainder by the number of cubic 
centimeters representing the capacity of the container. The quotient 
is the specific gravity, which can be thus determined within +2 in 
the second decimal place. __ : 

(d@) Mrxine witn Linsnep Orn.—One hundred grams of the paste 
shall be placed in a cup, 70 cc linseed oil added slowly with careful 
stirring and mixing with a spatula or paddle. The resulting mixture. 
must be smooth and of good brushing consistency. 

(ec) Moisture aNp Oruer VouaTite Marrer.—Weigh accurately 
from 3 to 5 g of the paste into a tared flat-bottomed dish about 8 
cm in diameter, spreading the paste over the bottom. Heat at 105 
to 110° O. for three hours, cool, and weigh. Calculate loss in weight 
as percentage of moisture and volatile matter. Hes 

(f) Percentage or Prament.—Weigh accurately about 15 ¢g of 
the paste into a weighed centrifuge tube. Add 20 to 30 cc of “extrac- 
tion mixture” (see reagents), mix thoroughly with a glass rod, wash 
the rod with more of the extraction mixture, and add sufficient of 


the reagent to make a total of 60 ce in the tube. Place the tube in 4 


the container of a centrifuge, surround with water, and counter- 
balance the container of the opposite arm with a similar tube or a 
tube with water. Whirl at a moderate speed until well settled. 


SPECIFICATION FOR BLACK PAINT D 


Decant the clear supernatant liquid. Repeat the extraction three 
times with 40 cc of extraction mixture. After drawing off the ex- 
traction mixture, set the tube in a beaker of water at about 80° C. 
or on top of a warm oven for 10 minutes, then in an oven at 105 to 
110° C. for two hours. Cool, weigh, and calculate the percentage 
of pigment. Grind the pigment to a fine powder, pass through a 
No. 80 screen to remove any skins, and preserve in a stoppered 
bottle. 

Notr.—If the pigment fails to settle with the “extraction mixture,’’ use 
petroleum ether, 100 per cent of which distils below 70° C., 75 per cent below 
50° C., with an initial boiling point of 28° C. 

(g) PREPARATION oF Farry Acips.—To about 25 g of the paste 
in a porcelain casserole, add 15 cc of aqueous sodium hydroxide 
(see Reagents) and 75 cc of ethyl alcohol, mix and heat uncovered 
on a steam bath until saponification is complete (about one hour). 
Add 100 cc of water, boil, add sulphuric acid of specific gravity 1.2 
(8 to 10 cc in excess), boil, stir, and transfer to.a separatory funnel to 
which some water has been previously added. Draw off as much as 
possible of the acid aqueous layer, wash once with water, then add 
50 cc of water and 50 ccof ether. Shake very gently with a whirling 
motion to dissolve the fatty acids in the ether, but not so violently 
as to form an emulsion. Draw off the aqueous layer and wash the 
ether layer with one 15 cc portion of water and then with 5 cc por- 
tions of water until free from sulphuric acid. Then draw off the 
water layer completely. Transfer the ether solution to a dry flask 
and add 25 to 50 g of anhydrous sodium sulphate. Stopper the flask 
and let stand with occasional:shaking at a temperature below 25° C. 
until the water is completely removed from the ether solution, which 
will be shown by the solution becoming perfectly clear above the 
solid sodium sulphate. Decant this clear. solution, if necessary, 
through a dry filter paper, into a dry 100 cc Erlenmeyer flask. Pass 
a rapid current of dry air (pass through a CaCl, tower) into the mouth 
of the Erlenmeyer flask and heat to a temperature below 75° C. on a 
dry hot plate until the ether is entirely driven off. 
~ Norsz.—It is important to follow all of the details since ether generally containg 
alcohol and after washing with water always contains water. It is very difficult 
to remove water and alcohol by evaporation from fatty acids, but the washing 
of the ether solution and subsequent drying with anhydrous sodium sulphate 
removes both water and alcohol. Ether, in the absence of water and alcohol, 
is easily removed from fatty acids by gentle heat. 

The fatty acids prepared as above should be kept in a ct ec maredt 
flask and examined at once. 

(kh) Test ror Minera O1L AND OTHER UNSAPONIFIABLE Mat- 
TER. —Place 10 drops of the anid acid ees in a 50 cc test sath add 


6 CIRCULAR OF THE BUREAU OF STANDARDS 


5 cc of alcoholic soda (see Reagents), boil vigorously for five minutes 
add 40 cc of water, and mix; a clear solution indicates that not more 
than traces of unsaponifiable matter are present. If the solution is 
not clear, the oil is not pure linseed oil. 

(1) Ioptnzs Numper or Farry Acips.—Place a small quantity of 
the fatty acids (g) in a small weighing burette or beaker. Weigh 
accurately. Transfer by dropping from 0.09 to 0.15 g into a 500 ce 
bottle having a well-ground glass stopper, or an Erlenmeyer flask 
having a specially flanged neck for the iodine test. Reweigh the 
burette or beaker and determine amount of sample used. Add 10 cc 
of chloroform. Whirl the bottle to dissolve the sample. Add 10 ce 
of chloroform to each of two empty bottles like that used for the sam- 
ple. Add to each bottle 25 ce of the Wijs solution (see Reagents) and 
let stand with occasional shaking for one hour in a dark place at a 
temperature of from 21 to 23° C. Add 10 ce of the 15 per cent 
potassium iodide solution and 100 ec of water, and titrate with 
standard sodium thiosulphate, using starch as indicator. The titra- 
tions on the two blank tests should agree within 0.1 cc. From the 
difference between the average of the blank ‘titrations and the titra- 
tion on the sample and the iodine value of the thiosulphate solution, 
calculate the iodine number of the sample tested. (Jodine number 
is centigrams of iodine to 1 g of sample.) If the iodine number is 
less than 175, the oil does not meet the specification. 

(j) Coarse ParrioLes AND Sxins.—Dry in an oven at 105 to 
110° C. a No. 325 screen, cool, and weigh accurately. Weigh an 
amount of semipaste containing 10 g of pigment (see 2 (f)), add 50 ce 
of kerosene, mix thoroughly, and wash with kerosene through the 
screen, breaking up all lumps but not grinding. After washing with 
kerosene until all but the particles too coarse to pass the screen have 
been washed through, wash all kerosene from the screen with ether 
or petroleum ether, eat the screen for one sri ‘at eon to’ eats C., 
cool, and weigh. ol 

3. ANALYSIS OF PIGMENT: 


(a) QuaLiTaTIvE ANALYsIs.—Make qualitative analysis following 
ordinary methods. 

(6) Loss on Ianit1ion.—Ilgnite 1 g of the pigment in a weighed 
porcelain crucible until all carbon is consumed. It is best to use 
gentle heat with free access of air. Cool, weigh, and ca‘culate 
the percentage of loss on ignition. © 

(c) CarBoN AND InsoLUBLE MinERaL Marerian.—Place 1 g of 
the pigment in a porcelain dish, moisten with a few drops of alcohol, 
add 20 cc of concentrated hydrochloric acid, cover, and heat on 
steam bath for 15 minutes. Remove cover and evaporate to dryness, 
moisten with hydrochloric acid, add 25 cc of water, filter on a 


~~ ee ee Pe eS zi 


Ce. a ee ee ee ee Pe ey 


\ 


SPECIFICATION FOR BLACK PAINT ‘f 


weighed Gooch crucible, and wash with hot water until the washings 
are free from lead and iron. Dry the crucible and contents at 
105 to 110° ©. for 2 hours. Ignite for 7 minutes in a current of 
dry carbon dioxide (using a Rose crucible cover) with a flame about 
20 cm high. Cool in a current of dry carbon dioxide and weigh. 
Then ignite with free access of air (or in a current of oxygen) until 
all carbon is consumed. Cool and weigh. The loss in weight is: 
calculated’ as carbon, and the residue remaining on the Gooch 
crucible is calculated as insoluble mineral material. 

(7) Leap Oxipze anp Iron Oxipe.—Determine lead and iron 
in the filtrate from the carbon determination by any convenient 
method, calculating lead:to Pb;O, and iron to Fe,O3;. 


4, LABORATORY EXAMINATION—MIXED PAINT 


(a) Caxine 1n Contariner.—Follow the procedure outlined in 
2 (a), noting that the paint should be no more difficult to break up 
than a good grade of mixed paint. 

(b) Cotor.—Follow the procedure outlined in 2 (6). 

(c) Weicur PER GALLoN.—Weigh a clean, dry, 100 cc graduated 
flask. Fill to the mark with the thoroughly mixed paint and weigh 
again. The increase in weight expressed in grams, divided by 100, 
gives the specific gravity, which multiplied by 8.33 gives the weight 
in pounds per gallon. 

(2) BrusHING PRorERTIES AND Time oF Dryine.—Brush the 
well-mixed paint on a suitable panel, which may be ground glass, 
steel, or well-filled wood. Note whether the paint works satis- 
factorily under the brush. Place the panel in a vertical position in 
a well-ventilated room and let stand for 18 hours. The paint shall 
be dry, smooth, and free from streaks. Flow a portion of the. paint 
on a clean glass plate. Let dry in a nearly vertical position at room 
temperature (65 to 100° F.).. The film shall show no streaking or 
separation within a distance of 4 inches from the top. 

(e) Water.—Mix 100 g of the paint in a 500 cc short ee glass 
flask! with 75 cc of toluol (free from water). Connect with the dis- 
tilling trap and condenser and heat so that the condensed distillate 
falls from the end of the condenser at the rate of from two to five 
drops per second. Continue the distillation at the specified rate 
until no water is visible on any part of the apparatus except at the 
bottom of the trap. This operation usually requires less than an 
hour. A persistent ring of condensed water in the condenser tube 
should be: removed by increasing the rate of distillation for a few 
minutes. The number of cubic centimeters of condensed water 

1 The apparatus for determining water is that described in ‘“‘Standard method of test for water in petro- 


jeum products and other bituminous materials,’”’ Serial Designation D-95-24, A.S, T. M. Standards, 
1924, p. 901 and Figure 1 (0) and (c), p. 902, 


8 CIRCULAR OF THE BUREAU OF STANDARDS 


measured in the trap at room temperature is the percentage of water 
in the paint. 

(f) VotaTiLe THInNeR.—Follow the procedure outlined in 2 (e). 
Correct the result for any water found (see 4 (e)) and report the 
remainder as a volatile thinner. 

(g) Percentacre or Picment.—Follow the procedure outlined in 
2 

(h) Testing NonvouatiLe VexHicite.—Follow the proéedure out- 
lined in 2 (g), 2 (A), and 2 (2), except that in the preparation of the 
fatty acids the mixture of paint and alkali is heated on the steam 
bath until all yolatile thinner is driven off. 

(1) Coarse ParticLes aND Sxins.—Follow the procedure out- 
lined in 2 (9). 

(7) Testing Piement.—Follow the Procedure outlined in 3 (a) 
to 3 (d), inclusive. 

5. REAGENTS 


(a) Extraction Mrxturrt.— 

10 volumes ether (ethyl ether). 
6 volumes benzol. 

4 volumes methyl alcohol. 

1 volume acetone. 

(6) Aquzous Soprum Hyproxipr.—Dissolve 100 g of sodium 
hydroxide in distilled water and dilute to 300 cc. } 

(c) Stanparp Sopium TuHiosuLpHaTe SoLutTion.—Dissolve pure 
sodium thiosulphate in distilled water (that has been well boiled 
to free it from carbon dixoide) in the proportion of 24.83 g of crys- 
talized sodium thiosulphate to 1,000 cc of the solution. It is best 
to let ‘this sdlution stand for about two weeks before standardizing. 
Standardize with pure resublimed iodine. (See Treadwell -Hall, 
Analytical Chemistry, vol. 2, 6th ed., p. 551.) This solution. will be 
approximately decinormal, inl it is best to leave it as Ib is after 
determining its exact iodine value, rather than to attempt to adj ust 
it to exactly decinormal. Preserve in a stock bottle provided with 
a guard tube filled with soda lime. 

(d) Starcu So.ution.—Stir up 2 to 3 g of potato starch | or ‘5 g 
of soluble starch with 100 cc of 1 per cent salicyclic acid solution, 
add 300 to 400 cc boiling water, and boil the mixture until the starch 
is practically dissolved, then dilute to 1 liter. 

(e) PoTasstum Topipz SoLuTiIon.—Dissolve 150 g of ‘potassium 
iodide free from iodate in distilled water and dilute to 1 ,000 cc. 

(f) Wiss Sonution.—The preparation of the iodine monochloride 
solution presents no great difficulty, but it should be done with care 
and accuracy in order to obtain satisfactory results. There shall be 
in the solution no sensible excess either of iodine, or more particu- 


SPECIFICATION FOR BLACK PAINT 9 


larly of chlorine over that required to form the monochloride. This 
condition is most satisfactorily attained by dissolving in the whole 
of the acetic acid to be used the requisite quantity of iodine, using 
gentle heat to assist the solution, if it is found necessary. Dissolve 
iodine in glacial acetic acid that has a melting point of 14.7 to 15° te: 
and is free from reducing impurities in the proportion so that 13 g | 
of iodine will be present in 1,000 cc of solution. Set aside a small 
portion of this solution while pure, and pass dry chlorine into the 
remainder until the halogen content of the solution is doubled. 
Ordinarily it will be found that by passing the chlorine into the 
main part of the solution until the characteristic color of free iodine 
has just been discharged there will be a slight excess of chlorine 
which is corrected by the addition of the requisite amount of the 
unchlorinated portion until all free chlorine has been destroyed. 
A slight excess of iodine does little or no harm, but excess of chlorine 
must be avoided. 

(g) Auconotic Sopium HypRroxIpE SoLuTion.—Dissolve pure 
sodium hydroxide in 95 per cent ethyl alcohol in the proportion 
of about 22 g per 1,000 cc. Let stand in a stoppered bottle. 
Decant the clear liquid into another bottle and keep well stoppered. 
This solution should be colorless or only slightly yellow when used, 
and it will keep colorless longer if the alcohol is previously treated 
with sodium hydroxide (about 80 g to 1,000 cc), kept at about 
50° C. for 15 days, and then distilled. 


VII. PACKING AND MARKING OF SHIPMENTS 


Ci 


Shall be in accordance with commercial practice unless otherwise 
specified. | 
VIII. NOTES 


Black paint may be ordered in the form of either semipaste paint 
or ready-mixed paint. The semipaste may be purchased by net 
weight or by volume. The ready-mixed paint should be purchased 
by volume (231 cubic inches to the gallon). 

For formulas and methods of using this material and information 
regarding the use of other specification paint materials see Bureau 
of Standards Technologic Paper No. 274, entitled ‘Use of United 
States Government Specification Paints and Paint Materials.” 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDEN1 OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. | 

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DEPARTMENT: OF COMMERCE. 
BUREAU OF STANDARDS. 


S. W. STRATTON, Director. 


CIRCULAR OF THE BUREAU OF STANDARDS, 


No. 97. 


[3d edition. Issued July 3, 1922.] 


UNITED STATES GOVERNMENT SPECIFICATION FOR 
GREEN PAINT, SEMIPASTE AND READY MIXED. 


FEDERAL SPECIFICATIONS BOARD. 
STANDARD SPECIFICATION NO. 15. 


This Specification was officially adopted by the Federal Specifications Board on 
February 3, 1922, for the use of the Departments and Independent Establish- 
ments of the Government in the purchase of materials covered by it. 


CONTENTS. 

Page 
See ee ee eee ts Oe ats, Does OLR. Ae. at. I 
Mk wy is wt ee ee vw wd letStay'y «Reb bolerg eres lddawe are wwlaieye * 
ee eeeetgee @xaimitiation of semipaste: .... 2.6.6. ee eee eee teens 3 
rear Ses rr rk BGI ee We de bu wR Ue eS Ges 6 
Sauer y examination of mixed paint... ...... 0.06... ccc cece cee neeens 8 
Ee Ey Ck cle kets dene sree cbocsheutecescuees 9 

1. GENERAL. 


The paint contemplated by this specification is a chrome green 
paint, and it may be ordered either in the form of semipaste 
pigment ground in linseed oil or as ready-mixed paint. 

The basis of purchase may be either net weight or volume (231 
cubic inches to the gallon). 

(a) PicMENT.—The pigment in ath semipaste and ready- 
mixed paints should be a chrome green containing about 23 per 

109836°—22—1 


2 Circular of the Bureau of Standards 


cent of color (sum of lead chromate and insoluble Prussian blue), 
about ro per cent of magnesium silicate, aluminum silicate, or 
similar siliceous material, and about 67 per cent of barium sul- 
phate. It should be made by precipitating the color on the 
proper base rather than by mixing the individual materials. It 
must yield on analysis: 


Maximum.| Minimum, 


Per cent. Per cent. . 


Color (total lead chromate and insoluble Prussian blue)... .........0.eeeees eee ee fener ees enese 20 
Material soluble in water, including soluble Prussian blue.................-.-.- O27 li ticaknieers 
Acid-soluble calcium in any form, calculated as CaO........22222.--ee nee eee ees Bio Sl Bn a 
Material other than color and barium sulphate. ......... 0.00... cence seco ee erres a9 Saran 


The remainder must be barium sulphate. 
a le ee 

(b) Liquip.—The liquid in semipaste paint shall be entirely 
linseed oil; in ready-mixed paint it shall contain not less than 90) 
per cent aioe oil, the balance to be combined drier and thinner. 
The thinner shall be turpentine, volatile mineral spirits, or a 
mixture thereof. 

(c) SEMrpasTtE.—Semipaste paint shall be made by thoroughly 
grinding the pigment with linseed oil. | 

The semipaste as received and three months thereafter shall be 
not caked in the container and shall break.up readily in.linseed 
oil to form a smooth paint of brushing consistency. It shall.mix 
readily with linseed oil, turpentine, or volatile mineral spirits, or 
any combination of these substances, in all proportions, without 
curdling. ‘The color and hiding power when specified shall be 
equal to that of a sample mutually agreed upon by buyer and 
seller. The weight per gallon shall be not less than 16 mina 
The paste shall consist of: 


Per cent. Per cent. 
Pigment noes ow bs hie vin pein 4.9 a iple. 09 010 0 0 gh bp copay pereealle naire 1a le laters ee 72 68 


Linseed ob... ccs oc ccc a boc vice suis nialiicie «cmttele O Ie DA: IOk MeBeGM ab Ae tena eisai’ 32 28 

Moisture and other volatile matter... fis ccuccccenrenes segs oe eeeee ener OT Aessaaao cna 

Coarse particles and ‘‘skins”’ (total residue retained on No. 325 screen based on ' ead 
pigmen: t) Poe em ree eee HoH EH ERE HH EHH OHHH TEES ETOH OHH SEHR HEHEHE HS TEE HE HD eee rer eee ere > 4 }25 & Re. -  a 


(d) Reapy-Mrxep Parnt.—Ready-mixed paint shall; be» well 
ground, shall not settle badly or cake in the container, shall be 
readily broken up with a paddle to a smooth uniform paint of good 
brushing consistency, and shall dry within 18 hours to a full oil 
gloss, without streaking, running, or sagging. The ‘color and 
hiding power when specified shall be equal to those of a sample 


Specification for Green Patnt 3 


mutually. agreed upon by buyer and seller. The weight per gallon 
shall be not less than 12 pounds. ‘The paint shall consist of: 


Maximum.| Minimum. 


Percent. | Percent. 
Pigm 55 50 


CC ee 


Liguia ( ‘eighties at least 90 per cent linseed oil)... 0.00. lee cee wees 50 : 45 

aa aN ET Ue SE aac 5 cites oy'2)4 AL. A/a ale. dibveig le ayals: bv 0 die ol ewe cd ape oO Vio alan EE a aap oe 

Coarse particles and ‘‘skins’’ (total residue retained on No. 325 screen based on 
i ac Gio dis dm a pieige ng 5 ve MA cleus $x oe raddee engin te hl eee ieee 


Note.—Deliveries will, in general, be sampled and tested by the following methods, but the purchaser 
reserves the right to use any additional available information to ascertain whether the material meets 


_ the specification. 
2. SAMPLING. 


It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1000 packages shall be taken 
as representative of the whole. Whenever possible an original 
unopened container shall be sent to the laboratory, and when this 
is for any reason not done, the inspector shall determine by thorough 
testing with a paddle or spatula whether the material meets the 
requirement regarding caking in the container. He shall then 
-thoroughly mix the contents of the container and draw a sample 
of not less than 5 pounds. ‘This sample shall be placed in a clean, 
dry metal or glass container, which it must nearly fill. The con- 
tainer shall be closed with a tight cover, sealed, marked, and sent 
to the laboratory for test with the inspector’s report on caking. 

When requested, a duplicate sample may be taken from the 
same package and delivered to the seller, and the inspector may 
take a third sample to hold for test in case of dispute. 


RA LABORAT ORY EXAMINATION OF SEMIPASTE. 


(a) CAKING IN CONTAINER. — When an original package is 
‘received in the laboratory it shall be weighed, opened, and stirred 
with a stiff spatula or paddle. ‘The paste must be no more diffi- 
cult to break up than a normal good grade of semipaste paint. 
The semipaste shall finally be thoroughly mixed, removed from 
the container, and the container wiped clean and weighed. This 
weight subtracted from the weight of the original package gives 
the net weight of the contents. A portion of thoroughly mixed 
semipaste shall be placed in a clean container and the portions 
for the remaining tests promptly weighed out. 

(b) CoLtor.—Place some of the paint on a clean, clear glass 
plate. Place some of the standard agreed upon beside the sample 
on the plate, turn the glass over, and compare the colors. 


4 | Circular of the Bureau of Standards 


(c) WEIGHT PER GALLON.—From the weight of a known volume 
of the paste calculate the specific gravity, which multiplied by 
8.33 gives the weight in pounds per gallon. Any suitable con- 
tainer of known volume may be used for the purpose, but a short 
cylinder of heavy glass with rounded bottom about 75 mm high ° 
and having a capacity of from 125 to 175 cc (a glass cap to keep 
dust from reagent bottle stopper) is a convenient apparatus for 
the purpose. ‘The capacity of this vessel is determined to within 
1 cc. The paste is packed into it until completely full, the top 
leveled off smooth with a spatula, and weighed to +0.5 g. Sub- 
tract the weight of the empty container and divide the remainder 
by the number of cubic centimeters representing the capacity of 
the container. The quotient is the specific gravity, which can be 
thus determined within +2 in the second decimal place. 

(d) Mrxinc wit LinskED O1.—One hundred grams of the 
paste shall be placed in a cup, 30 cc of linseed oil added slowly with 
careful stirring and mixing with a spatula or paddle. ‘The result- 
ing mixture must be smooth and of good brushing consistency. 

(e) MotstrurE AND OTHER VOLATILE Matrer. — Weigh accu- 
rately from 3 to 5 g of the paste into a tared flat-bottomed dish 
about 8 cm in diameter, spreading the paste over the bottom. 
Heat at 105 to 110° C, for three hours, cool, and weigh. Calculate 
loss in weight as percentage of moisture and volatile matter. 

({) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 ¢ 
of.the paste into a weighed centrifuge tube. Add 20 to 30 cc of 
‘extraction mixture” (see reagents), mix thoroughly with a glass 
rod, wash the rod with more of the extraction mixture, and add 
sufficient of the reagent to make a total of 60 cc in the tube. 
Place the tube in the container of a centrifuge, surround with 
water, and counterbalance the container of the opposite arm 
with a similar tube or a tube with water. Whirl at a moderate 
speed until well settled. Decant the clear supernatant liquid. 
Repeat the extraction twice with 40 cc of extraction mixture and 
once with 40 ce of ether. After drawing off the ether, set the 
tube in a beaker of water at about 80° C. or on top of a warm oven 
for 10 minutes, then in an oven at 105 to 110° C. for two hours. 
Cool, weigh, and calculate the percentage of pigment. Grind 
the pigment to a fine powder, pass through a No. 80 screen to 
remove any skins, and preserve in a stoppered bottle. 

(g) PREPARATION OF Farry Acimps.—To about 25 g of the 
paste in a porcelain casserole, add 15 cc of aqueous sodium 


Specification for Green Paint 5 


hydroxide (see reagents) and 75 cc of ethyl alcohol, mix and 
heat uncovered on a steam bath until saponification is complete 
(about one hour). Add 100 cc of water, boil, add sulphuric 
acid of ‘specific gravity 1.2 (8 to 10 ce in excess), boil, stir, and 
transfer to a separatory funnel to which some water has been 
previously added. Draw off as much as possible of the acid 
aqueous layer, wash once with water, then add 50 cc of water 
and 50 cc of ether. Shake very gently with a whirling motion 
to dissolve the fatty acids in the ether, but not so violently as 
to form an emulsion. Draw off the aqueous layer and wash 
the ether layer with one 15 cc portion of water and then with 
5 ce portions of ‘water until! free from sulphuric acid. Then 
draw off the water layer completely. Transfer the ether solution 
to a dry flask and add 25 to 50 g anhydrous sodium sulphate. 
Stopper the flask and let stand with occasional shaking at a 
temperature below 25° C. until the water is completely removed 
from ‘the ether solution, which will be shown by the solution 
becoming perfectly clear above the solid sodium sulphate. Decant 
this clear solution, if necessary, through a dry filter paper, into 
a dry roo cc Erlenmeyer flask. Pass a rapid current of dry air 
(pass through a CaCl, tower) into the mouth of the Erlenmeyer 
flask and heat to a temperature below 75° C. on a dry, hot plate 
until the ether is entirely driven off. ; 


NoTe.—It is important to follow all of the details, since ether generally contains 
alcohol and after washing with water always contains water. It is very difficult 
to remove water and alcohol by evaporation from fatty acids, but the washing of the 
ether solution and subsequent drying with anhydrous sodium sulphate removes both 
water and alcohol. Ether, in the absence of water and alcohol, is easily removed 
from fatty acids by gentle heat. 

The fatty acids prepared as above should be kept in a stoppered 
flask and examined at once. 

(hk) Test FoR MINERAL OIL AND OTHER UNSAPONIFIABLE 
Marter.—Place 10 drops of the fatty acids (g) in a 50 cc test 
tube, add 5 cc of alcoholic soda (see Reagents), boil vigorously 
for five minutes, add 40 cc of water, and mix; a clear solution 
indicates that not more than traces of unsaponifiable matter are 
present. If the solution is not clear, the oil is not pure linseed oil. 

(4) IopIne NuMBER OF Farry Acips.—Place a small quantity of 
the fatty acids (g) in a small weighing burette or beaker. Weigh 
accurately. ‘Transfer by dropping about 0.15 g (0.10 to 0.20 g) 
into a 500 cc bottle having a well-ground glass stopper, or an 
Erlenmeyer flask having a specially flanged neck for the iodine 

109836 °—22——-2 


6 Circular of the Bureau of Standards 


test. Reweigh the burette or beaker and determine amount of 
sample used. Add 10 cc of chloroform. Whirl the bottle to 
dissolve the sample. Add io cc of chloroform to two empty bot- 
tles like that used for the sample. Add to each bottle 25 ce of 
the Hanus solution (see reagents) and let stand with occasional 
shaking for one-half hour. Add 10 ec of the 15 per cent potas- 
sium iodide solution and 100 ce of water, and titrate with stand- 
ard sodium thiosulphate, using starch as indicator. The titrations 
on the two blank tests should agree within o.1 ce. From the 
difference between the average of the blank titrations and: the 
titration on the sample and the iodine value of the thiosulphate 
solution, calculate the iodine number of the sample tested. (Io- 
dine number is centigrams of iodine to 1 g of sample.) If the - 
iodine number is less than 170, the oil does not meet the specifica- 
tion. im teehee 
(7) COARSE PARTICLES AND SKINS.—Dry in an oven at 105 to 
110° C. a No. 325 screen, cool, and weigh accurately. Weigh an 
amount of semipaste containing 10 g of pigment. (see 3 (/)), add 
50 cc of kerosene, mix thoroughly, and wash with kerosene 
through the screen, breaking up all lumps but not grinding. After 
washing with kerosene until all but the particles too coarse to pass 
the screen have been washed through, wash all kerosene from the 
screen with ether or petroleum ether, heat the screen for one hour 
at 105 to 110° C., cool, and weigh. 


4. ANALYSIS OF PIGMENT. 


(a) QUALITATIVE ANALYsIS.—Test for Prussian blue by boiling a 
portion of the pigment with sodium hydroxide solution. A yellow 
or yellow-brown precipitate with a yellow liquid above it should 
result. Filter, add a mixture of ferric and ferrous salts to the 
filtrate, and render acid with dilute hydrochloric acid. A blue 
color indicates Prussian blue in the sample. Ignite another por- 
tion very gently to decompose the Prussian blue and make a 
qualitative analysis of the residue. 

(b) MaTteR SOLUBLE IN WATER.—Transfer 2.5 g of the pig- 
ment to a graduated 250 cc flask, add 100 ce of water, boil for 
5 minutes, cool, fill to mark with water, mix, and allow to settle. 
Pour the supernatant liquid through a dry paper and discard the 
first 20 ec. Then evaporate too cc of the clear filtrate to dryness 
in a weighed dish, heat for one hour at 105 to 110° C., cool, and 
weigh. 


Specification for Green Paint 7 


(c) BARIUM SULPHATE AND SILICEOUS MATERIAL.—Heat a 1 g 
portion of the pigment very gently in a small porcelain dish. 
The heat must be so regulated by moving the burner that the 
Prussian blue is thoroughly decomposed without rendering the 
iron difficultly soluble. Allow to cool, transfer to a 400 cc beaker, 
add 20 cc of concentrated hydrochloric acid, heat on steam bath 
for 30 minutes, boil for 5 minutes, dilute with hot water to about 
250 ce, filter on paper while hot, wash thoroughly with hot water 
until the washings are free from lead and chlorine, and ignite and 
weigh the residue, which will be barium sulphate and siliceous 
material. Mix the ignited residue with about 10 times its weight 
of anhydrous sodium carbonate (grinding the mixture in an agate 
mortar if necessary), and fuse the mixture in a covered platinum 
crucible, heating about one hour. Let cool, place crucible and 
cover in a 250 cc beaker, add about 100 cc of water, and heat 
until the melt is disintegrated. Filter on paper (leaving crucible 
and cover in beaker) and wash the beaker and filter thoroughly 
with hot water to remove soluble sulphates. Place the beaker 
containing the crucible and cover under the funnel, pierce the 
filter with a glass rod, and wash the carbonate residue into the 
beaker by means of a jet of hot water. Wash the paper with hot, 
dilute hydrochloric acid (1:1), and then with hot water. If the 
carbonate residue is not completely dissolved, add sufficient dilute 
hydrochloric acid to effect solution, and remove crucible and cover, 
washing them with a jet of water. Heat the solution to boiling 
and add ro to 15 cc of dilute sulphuric acid, and continue the 
boiling for 10 or 15 minutes longer. Let the precipitate settle, 
filter on a weighed Gooch crucible, wash with hot water, ignite, 
cool, and weigh as BaSO,. Subtract from the result of the 
previous determination to obtain the siliceous material. 

(d) [wap AND CHROMIUM.—Unite the filtrate and washings 
from barium sulphate and siliceous material (see (c)), dilute to 
soo cc, neatly neutralize with ammonium hydroxide, and pass 
in a rapid stream of hydrogen sulphide until all the lead is pre- 
cipitated as PbS; filter, wash with water containing a little hydro- 
gen sulphide, dissolve in hot nitric acid (1:3), and determine lead 
as sulphate in usual manner, weighing as PbSQ,. Boil the fil- 
trate from the lead sulphide to expel hydrogen sulphide. Add 
sodium peroxide in sufficient amount to render the solution: alka- 
line and to oxidize the chromium to chromate. Boil until the 
hydrogen peroxide is driven off, cool, acidify with sulphuric acid 


8 Circular of the Bureau of Standards 


(1:4), add a measured excess of a freshly prepared solution of 
ferrous sulphate, and titrate the excess of ferrous iron with stand- 
ard potassium dichromate, using potassium ferricyanide solution 
as outside indicator. ‘Titrate a blank of an equal volume of the 
ferrous sulphate solution with the standard potassium dichromate. 
From the difference between the titration on the blank and on 
the sample, calculate the chromium in the sample to PbCrO,,. 
From the PbCrO, found, calculate the equivalent of PbSO, by 
multiplying by the factor 0.938. Subtract this value from the 
-total PbSO, found above and report the remainder as lead com- 
pounds other than chromate, calculated as PbSO,.” |” | 

(ce) Catcrum.—Ignite 2 g of the pigment’ and dissolve the 
residue in hydrochloric acid as in 4(c). Then, without filtering 
from the insoluble matter, transfer to a 500 éc volumettic flask, 
saturate with hydrogen sulphide, make alkaline with ammonia, 
fill to the mark, mix, and filter through a dry paper, discarding 
the first 20 cc. Then determine the calcium in 250 ce of the 
filtrate (corresponding to 1 g pigment) by precipitztion as oxalate 
and weighing as calcium oxide. 

(f) Cotor.—Add the percentages of matter Sitti in wate 
4(b), barium sulphate and siliceous material 4(c), lead compounds 
other than chromate calculated as PbSO, 4(d); and calcium oxide 
4(e) and subtract the sum from roo. Call the tei shirt ite the 
percentage of color. 


5, LABORATORY EXAMINATION OF MIXED volt ania 


(2) CAKING IN CoNTAINER.—Follow the procedure outlined in 
3(a), noting that the paint should be no more Hisiteso to eee ny 
than a good grade of mixed paint. | . 109 

(b) CoLor.—Follow the procedure outineds in 3(6). : 

(c) WEIGHT PER GALLON.—Weigh a clean, dry, 100 ec gradu- 
ated flask. Fill to the mark with the thoroughly mixed paint and 
weigh again. ‘The increase in weight expressed in grams, divided 
by 100, gives the specific gravity, which eras by 8. “33 hag 
the weight in pounds per gallon. 

(dq) BRUSHING PROPERTIES AND TIME OF DRYING. soiBaiaa the 
well-mixed paint on a suitable panel, which may be ground glass, 
steel, or well-filled wood. Note whether the paint works satis- 
factorily under the brush. Place the panel in a vertical position 


in a well-ventilated room and let stand for 18 hours. The paint 


should be dry and free from streaks. Flow a portion of the paint 
on a clean glass plate. Let dry in a nearly vertical position at 


{ 
bh 
: 
| 


Specification for Green Paint 9 


room temperature (65 to 100° F). ‘The film shall show no 
streaking or separation within a distance of 4 inches from the top. 

(ec) WATER.—Mix 100 g of the paint in a 300 cc flask with 75 cc 
of toluol. Connect with a condenser and distill until about 50 cc 
of distillate has been collected in a graduate. ‘The temperature in 
the flask should be then about 105° to 110° C. ‘The number of 
cubic centimeters of water collecting under the toluol in the re- 
ceiver is the percentage of water in the paint. 

(f) VOLATILE THINNER.—Follow the procedure outlined in 
3(e). Correct the result for any water found (see 5(e)) and report 
the remainder as volatile thinner. 

(9) PERCENTAGE OF PiGMENT.—Follow the procedure outlined 
in 3(7). 

(h) TestInc NONVOLATILE VEHICLE.—Follow the procedure 
outlined in 3(g), 3(h), and 3(z), except that in the preparation of 
the fatty acids the mixture of paint and alkali is heated on the 
steam bath until all volatile thinner is driven off. 

(i) COARSE PARTICLES AND SKINS.—Follow the procedure out- 
lined in 3(). 

(j) Testinc PicMEN?T.—Follow the procedure outlined in 4(a) 
to 4(e), inclusive. 


6. REAGENTS. 


(a) EXTRACTION MIXTURE.— 
| 5 volumes benzol. 
4 volumes methyl alcohol 
1 volume acetone. , 
(b) AguEous Soprum HyproxipE.—Dissolve 100 g of sodium 
hydroxide in distilled water and dilute to 300 cc. 
~ (ce) STANDARD SODIUM THIOSULPHATE SOLUTION.— Dissolve pure 
sodium thiosulphate in distilled water (that has been well boiled 
to free it from carbon dioxide) in the proportion of 24.83 g crys- 
tallized sodium thiosulphate to 1,000 cc of the solution. It is 
best to let this solution stand for about two weeks before stan- 
dardizitig. Standardize with pure resublimed iodine. (See Tread- 
well-Hall, Analytical Chemistry, vol. 2, 3d ed., p. 646.) This so- 
lution will be approximately decinormal, and it is best to leave 
it as it is after determining its exact iodine value, rather than to 
attempt to adjust it to exactly decinormal. Preserve in a stock 
bottle provided with a guard tube filled with soda lime. 
(d) Starcu SOLUTION.—Stir up to 2 to 3 g of potato starch or 
5 g of soluble starch with 100 ce of 1 per cent salicylic acid solu- 


10 Circular of the Bureau of Standards 


tion, add 300 to 400 cc boiling water, and boil the mixture until 
the starch is practically dissolved, then dilute to r liter. | 

(e) Potassium IopiDE So_uTION.—Dissolve 150 g of potassium 
iodide free from iodate in distilled water and dilute to 1,000 ce. 

({) HANUS, SOLUTION.—Dissolve 13.2 g of iodine im 1,000 ec 
of 99.5 per cent glacial acetic acid, which will not reduce chromic 
acid. Add enough bromine to double the halogen content, deter- 
mined by titration (3 cc of bromine is about the proper amount). 
The iodine may be dissolved by the aid of heat, but the solution 
should be cold when the bromine is added. 

(g) ALcoHoLtic Soprum Hyproxie SoLuTION.—Dissolve pure 
sodium hydroxide in 95 per cent ethyl alcohol in the proportion 
of about 22 g per 1,o00cc. Let stand in a stoppered bottle. 
Decant the clear liquid into another bottle and keep well stop- 
pered. This solution should be colorless or only slightly yellow 
when used, and it will keep colorless longer if the alcohol is pre- 
viously treated with sodium hydroxide (about 80 ¢ to 1,006' ee), 
kept at about 50° C. for 15 days, and then distilled. 

(hk) STANDARD FERROUS SULPHATE SOLUTION.— Dissolve 14 g of 
pure crystallized ferrous sulphate (FeSO, 7H,O) in about 500 cc 
of water, to which 25 cc of concentrated H,SO, has been added, 
and then dilute to 1,000 cc. This solution should be freshly 
standardized when needed, as it does not keep well. 

(1) STANDARD PoTAssiIuM DICHROMATE SOLUTION.—Dissolve 
4.903 g of pure dry crystallized potassium dichromate in water 
and dilute to 1,000 cc. One cubic centimeter of this solution 
corresponds to 0.0108 g° PbCrO,, or o.o101 g PbSO,,. 

(j) PotasstuM FERRICYANIDE SOLUTION.—Dissolve a piece half 
as big as a small pea in 50 ce of water. This solution must be 
made fresh when wanted, because it does not keep. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT 


5 CENTS PER COPY 
V 


4 i 


WASHINGTON : GOVERNMENT PRINTING OFFICH : 1922 


et pees 
Tis t bed 


italy a: 
2D ae 
‘ “4 ‘ 


DEPARTMENT OF COMMERCE, 
BUREAU OF STANDARDS. 


CIRCULAR OF THE BUREAU OF STANDARDS. 
No. 98. 


[Second edition. Issued February 28, 1923.] 


UNITED STATES GOVERNMENT SPECIFICATION FOR 
VOLATILE MINERAL SPIRITS FOR THINNING PAINTS.’ 


FEDERAL SPECIFICATIONS BOARD. 


STANDARD SPECIFICATION No. 16. 
’ [Revised seciete 2, 1923.] 

This specification was officially adopted by the Federal Specifications Board 
on February 3, 1922, for the use of’ the departments and independent establish- 
ments of the Government in the purchase of volatile mineral spirits for thin- 
ning paints. 


CONTENTS. 

Page. 
ON SE eer en rar rte eee Tees eee eG I 
2. Detection and removal of separated water. ..........-- +s sere esse eee e eens 2 
@. Baap), 1.01 20 ES. OM LNT OR, BQ TIOO, AE ood e, AEP es 2 
4. Laboratory examination...........-. lhermo. ive. dormcrery Leela - bree: tp 8 
ge. Wags OF DULAC. orem ty he rte yt Ati biaee Fi beta aa? 9 

1. GENERAL. 


This specification applies only to petroleum distillates, known 
as mineral spirits. The material delivered under this specifica- 
tion shall conform to the following requirements: 

APPEARANCE.—Shall be cleat and free from suspended matter 
and water. | 

CoLor.—Shall be no darker than an aqueous solution of potas- 
sium dichromate containing 0.0048 g per liter (this corresponds to 
No. 21 Saybolt chromometer). 

Spot ‘Test.—Shall evaporate completely from filter paper. 

1 The mineral spirits called for in this specification is the same as that called for in Specifications for 


Petroleum Products, Bureau of Mines Technical Paper 323. 
27818°—23 


2 Circular of the Bureau of Standards. 


FLASH Pornt.—Shall be not lower than 30° C. (86° F.) when 
tested in a closed cup tester. 

BLACKENING.—Shall not blacken clean metallic copper. 

DisTILLATION.— Distillate below 130° C) (266° F.) shall not 
exceed 5 per cent. Distillate below 230° C. (446° F.) shall be 
not less than 97 per cent. 

Acrpity.—Shall be neutral. 


2. DETECTION AND REMOVAL.-OF SEPARATED WATER. 


Draw a portion by means of a glass or metal container with a 
removable stopper or top, or with a ‘‘thief,’’ from the lowest part 
of the container, or by opening the bottom valve of the perfectly 
level tank car. If water is found to be present, draw it all out, 
record the quantity, and deduct it from the total volume of liquid 
delivered. 

Note.—Deliveries will in general be sampled and tested by the following methods, 


but the purchaser reserves the right to use any additional available information to 
ascertain whether the material meets the specification. 


3. SAMPLING. 


The method of sampling given under (a) should be used when- 
ever feasible. When method (a) is not applicable, method (6), 


(c), or (d) is to be used, pasa to the special conditions that ~ 


obtain. 

(a) WHILE LOADING TANK Cap OR WHILE FILLING Comtanaes 
FOR SHIPMENT.—Samples shall be drawn by the purchaser’ s 
inspector at the discharge pipe where it enters the Teceiving 
vessel or vessels. The composite sample shall be not less than 5 
gallons and shall consist of small portions of not more than 1 
quart each taken at regular intervals during the entire period of 
loading or filling. The composite sample thus obtained shall be 


thoroughly mixed, and from it three samples of not less than 1 _ 


quart each shall be placed in clean, dry glass bottles or tin cans, 
which must be nearly filled with the sample and securely stoppered 
with new clean corks or well-fitting covers or caps. ‘These shall 
be sealed and distinctly labeled by the inspector. One shall be 
delivered to the buyer, one to the seller, and the third held for 
check in case of dispute. 

(6) From LoapEp Tank CAR OR OTHER LARGE VESSEL. —The 
composite sample taken shall be not less than 5 gallons and shall 
consist of numerous small samples of not more than 1 quart each 


taken from the top, bottom, and intermediate points by means — 


of a metal or glass container with removable stopper or top. 


Specification for Mineral Spirits. 3 


This device attached to a suitable pole is lowered to the various 
desired depths, when the stopper or top is removed and the con- 
tainer allowed to fill. The sample thus obtained is handled as 
in (a). 

(c) BARRELS AND Drums.—Barrels and drums shall be sampled 
after gauging contents. Five per cent of the packages in any 
shipment or delivery shall be represented in the sample. ‘Thor- 
oughly mix the contents of each barrel to be sampled by stirring 
with a clean rod and withdraw a portion from about the center 
by means of a ‘‘thief’’ or other sampling device. The com- 
posite sample thus obtained shall be not less than 3 quarts, shall 
consist of equal portions of not less than one-half pint from each 
package sampled, and shall be handled as in (a). Should the 
inspector suspect adulteration, he shall draw the samples from 
the suspected packages. 

(d) SMALL CONTAINERS, CANS, ETC., OF 10 GALLONS OR LESS.— 
These should be sampled, while filling, by method (a) whenever 
possible; but in case this is impossible, the composite sample 
taken shall be not less than 3 quarts. This shall be drawn from 
at least five packages (from all when fewer), and in no case from 
less than 2 per cent of the packages. The composite sample 
thus taken shall be thoroughly mixed and subdivided as in (a). 


4. LABORATORY EXAMINATION. 


(a) APPEARANCE.—Examine to determine compliance with the 
specification. 

‘(b) Coror.—Compare in any suitable apparatus the depth of 
color of the sample with the depth of color of a fresh solution of 
potassium dichromate in distilled water containing 0.0048 g K,Cr,O, 
per liter. (If desired, the color may be determined in a Saybolt 
chromometer, in which case the color must be no darker than » 
No. 21 on that scale.) 

(c) Spot Test.—Transfer five drops of the mineral spirits by 
means of a small pipette or burette to the center of a clean white 
filter paper supported on a 7-cm crystallizing dish and allow the 
liquid to evaporate at room temperature, away from direct sun- 
light. ‘There should be no oily spot left after 30 minutes. 

(d) FLasuH Pornt.—Determine with either the ‘Tag”’ or Elliott 
closed-cup tester. The former ‘is preferred.’ 


2 Directions for using the “‘T'ag’’ tester may be found in A. S. T. M. Standards Ds6-21 and in Bureau 
of Mines Technical Paper No. 323. Directionsfor using the Elliott cup may be found in Proceedings 
A.S. T. M., 1917, pt. 1, p. 414. 


4 Circular of the Bureau of Standards. 


(e) BLACKENING.—Place a clean strip of mechanically polished 
pure sheet copper, about 14 inch wide and 3 inches long (1.3 em 
by 7.5 cm) in a glass test tube about 34 inch wide and 18 inches 
long (1.9 by 46 cm). Add sufficient of the sample to be tested to 
completely cover the strip and heat rapidly to boiling (it is most 
convenient to heat the tube by immersion in an oil bath main- ~ 
tained at a temperature slightly higher than the initial boiling 
point of the mineral spirits): Keep the sample boiling, without any 
actual distillation taking place, for 30 minutes and then examine 
the copper strip for blackening. A slight tarnish shall be disre- 
garded, but any marked blackening shall be cause for rejection. 

({) DisTILLATION.—Use the A. S. T. M. (D 86-21 T) method 
as described below, except that it will be necessary to read the 
volume of the distillate at 130° C. and at 230° C. and the distilla- 
tion need not be carried beyond the 230° C. (446° F.) point. 


APPARATUS. 


Flask.—The standard 100 cc Engler flask is shown in aoe I, 
the dimensions and allowable tolerance being as follows: 7 


Dimensions of Engler flask. 


Centi- 
Description. Inches. 
| meters. (cm) 
Diameter of bulb, outside.) 05) 25. 3k ce Ae ee eee 6.5 2.56 0.2 
Diameter of neck, Side ld. FRITS. A. See 1.6 - 63 Pa 
Length of neck (7 2.022 hod set SSeS ee eee 15.0 5.91 4 
Length of vapor tube 3.553 ec aiss'coedoSevsn ds eee ee ee 10. 0 3.94 x8 
Diameter of vapor tube, outside............0. 0... c ec cece cece ce eecseceeveres -6 24 | . 05 
Diameter of vapor firbe, inside.: :< 66543. jie dee nike. ede bs » tom 2 Sade ‘E72 4 16 a!) 
Thickness of vapor tube wall. 0 v2.0%, «cs sess b nurse tren tesa bios he ear een ib . 04 -05 


The position of the vapor tube shall be 9 cm (3.55 inches) 
+3 mm above the surface of the liquid when the flask contains 
its charge of 100 cc. The tube is opp Oates in the middle 
of the neck and set at an angle of 75° (tolerance £3°) wash the 
vertical. 

Condenser.—The condenser (Fig. 2) consists of a 9/16 inch 
OD No. 20 Stubbs gauge seamless brass tube 22 inches long. 
It is set at an angle of 75° from the perpendicular and is 
surrounded with a cooling bath 15 inches long, approximately 
4 inches wide by 6 inches high. The lower end of the condenser 
tube is cut off at an acute angle and curved downward for a length 
of 3 inches and slightly backward, so as to insure contact with 


Specification. for Mineral Spirits. 5 


the wall of the graduate at a point 1 to 114 inches below the top 
of the graduate when it is in position to receive the distillate. 
Shield.—The shield (Fig. 2) is made of approximately 22- 
gauge sheet metal and is 19 inches high, 11 inches long, and 8 inches 
wide, with a door on one narrow side, with two openings, 1 inch in 


S 0.63" | Inside (Not outside) 
ae % LECH 
Ss 
as 
' Sapreeemer +e 
-O Se ae 
yf Ad a / 
+ = % 
aE s 
ry ON 


eee ee Level of liguid surface when 
tlask conjains too CC 


SEE 
COCM 
Outside 


Fic. 1.— Standard 100 cc Engler flask for use in making distillation tests. 


diameter, equally spaced, in each of the two narrow sides, and 
with a slot cut in one side for the vapor tube. The centers of these 
four openings are 814 inches below the top of the shield. There are 
also three 14-inch holes in each of the four sides, with their centers 
1 inch above the base of the shield. 

Ring support and hard asbestos boards —The ring support is of 
the ordinary laboratory type, 4 inches or larger in diameter, and 1s 

27818°—23-——2 


6 Circular of the Bureau of Standards. 


supported on a stand inside the shield. There are two hard 
asbestos boards, one 6 by 6 by % inch, with a hole 1% inches in 
diameter in its center, the sides of which shall be perpendicular to 
the surface; the other, an asbestos board to fit tightly inside the 
shield, with an opening 4 inches in diameter concentric with the 
ring support. These are arranged as follows: The second asbestos 
board is placed on the ring and the first or smaller asbestos board 
on top, so that it may be moved in accordance with the directions 
for placing the distilling flask. Direct heat is applied to the flask 
only through the 1 14-inch opening in the first asbestos board. 


lee Water Bath 
2" Outside Diameter 

~~~ No. 2. 20 Gage Seamless 
ie => Brass Tubing 


~ 
OP ie, ~ 
~ ~~ « 


am 


Fic. 2.—Distillation outfit (A. S. T. M.) arranged for use of gas burner. 


Gas burner or eleciric heater—Gas burner: The burner is so 
constructed that sufficient heat can be obtained to distill the 
product at the uniform rate specified below. ‘The flame should 
never be so large that it spreads over a circle of diameter greater 
than 3 %4 inches on the under surface of the asbestos board. A sen- 
sitive regulating valve is a necessary adjunct, as it gives phen 
control of heating. 

Electric heater: The electric heater, which may be used in 
place of the gas flame, shall be capable of bringing over ‘the first 


drop within the time specified below when started cold and of con-- 


tinuing the distillation at the uniform rate. ‘The electric heater 


Specification for Mineral Spirits. 7 


shall be fitted with an asbestos board top % to 14 inch thick, having 
a hole 134 inches in diameter in the center. When an electric 
heater is employed, the portion of the shield above the asbestos 
board shall be the same as with the gas burner, but the part below 
may be omitted. 

Thermometer.—A. S. T. M. high-distillation thermometer shall 
conform to the following specifications: 


Type: Etched stem glass. 

Total length: 381 mm. 

Stem: Plain front, enamel back, suitable thermometer tubing; diameter, 6 to 7 mm. 

Bulb; Corning normal, Jena 16 III, or equally suitable thermometric glass; length, 
to to 15 mm; diameter, 5 to 6 mm. 

Actuating liquid: Mercury. 

Range: 30 to 760° F., or o to 400° C. 

Immersion: Total. 

Distance to 30° F., or 0° C. mark from bottom of bulb: 25 to 35 mm. 

Distance to 760° F., or goo® C. mark from top of tube: 30 to 45 mm. 

Filled: Nitrogen gas. 

Top finish: Glass ring. 

Graduation: All lines, figures, and letters clear cut and distinct; scale graduated 
in 2° F. or 1° C. divisions and numbered every 20° F. or 10° C., the first and each 
succeeding 10° F. (5° C.) to be longer than the others. 

Special markings: A. S. T. M. High Distillation, serial number, and manufacturer’s 
name or trade-mark etched on the stem. 

Accuracy: Error at any point on scale shall not exceed one smallest scale division 
up to 700° F. or 370° C. 

Tests for permanency of range: After being subjected to a temperature of 700° F. 
or 370° C. for 24 hours the accuracy shall be within the limit specified. 


~ Points to be tested for certification: 32°, 212°, 400°, 700° F. or 0°, 100°, 200°, 370° C. 
7 37 


Graduate.—The graduate shall be of the cylindrical type, of 
uniform diameter, with a pressed or molded base and a lipped 
top. The cylinder shall be graduated to contain 100 cc and the 
graduated portion shall be not less than 7 inches nor more than 
8 inches long. It shall be graduated in single cubic centimeters, 
and each fifth mark shall be distinguished by alonger line. It shall 
be numbered from the bottom up at intervals of 10 cc. The dis- 


tance from the 100 cc mark to the rim shall be not less than 114 


inches nor more than 134 inches. ‘The graduations shall not be 
in error by more than 1 cc at any point on the scale. 


PROCEDURE. 


The condenser bath shall be filled with cracked ice* and 
enough water added to cover the condenser tube. The tempera- 
ture shall be maintained between 32 and 40° F. (o and 4.5°C.). 


- 8 Any other convenient cooling medium may be used. 


8 Circular of the Bureau of Standards. 


The condenser tube shall be swabbed to remove any liquid 
remaining from the previous test. A piece of soft cloth attached 
to a cord or copper wire may be used for this purpose. The 

The bulb of the distillation thermometer shall be covered 
uniformly with a long-fiber absorbent cotton weighing not less 
than 3 nor more than 5 mg. A fresh portion of clean cotton shall 
be used for each distillation. 

One hundred cubic centimeters of the tains shall teeta meas- 
ured in the 100 cc graduated cylinder at 55 to 65° F. (12.8 to 
18.3° C.) and transferred directly to the Engler flask. None of 
the liquid shall be permitted to flow into the vapor tube,  _ 

The thermometer provided with a cork shall be fitted tightly 
into the flask, so that it will be in the middle of the neck and so 
that the lower end of the capillary tube is on a level with the 
inside of the bottom of the vapor outlet tube at its iunation with 
the neck of the flask. 

The charged flask shall be placed in the 1r v, dict Shaeine 
in the 6 by 6 inch asbestos board, with the vapor outlet tube 
inserted into the condenser tube. A tight connection may be 
made by means of a cork through which the vapor tube passes. 
The position of the flask shall be so adjusted that the vapor tube 
extends into the condenser tube not less than 1 inek nor more ‘than 
2 inches. 

The graduated cylinder used in measuring the etlabae shall be 
placed, without drying, at the outlet of the condenser tube in 
such a position that the condenser tube shall extend into the 
graduate at least 1 inch but not below the 100 cc mark. Unless 
the temperature is between 55 and 65° F. (12.8 and 6 i i C.) the 
receiving graduate shall be immersed up to the 100 ce mark in a 
transparent bath maintained between these temperatures. The 
top of the graduate shall be covered closely during the distillation 
with a piece of blotting paper or its equivalent cut so as to at tng 
condenser tube tightly. 

When everything is in readiness, heat shall be applied at a 
uniform rate, so regulated that the first drop of condensate falls 
from the condenser in not less than. 5 nor more than 10 minutes. 
When the first drop falls from the end of the condenser, the 
reading of the distillation thermometer shall be recorded as the 
wnitial boiling point. ‘The receiving cylinder shall then be moved 
so that the end of the condenser tube shall touch the side of the 
cylinder. The heat shall then be so regulated that the distilla- 
tion will proceed at a uniform rate of not less than 4 nor more 


Specification for Mineral Spirits. 9 


than 5 cc per minute. The reading of the distillation thermometer 
shall be recorded when the level of the distillate reaches each 
10 ce matk on the graduate. After the 90 per cent point has 
been recorded, the heat may be increased because of the presence 
of the heavy ends which have high boiling points. However, no 
further increase of heat should be applied after this adjustment. 
The 4 to 5 cc rate can rarely be maintained from the 90 per cent 
point to the end of the distillation, but in no case should the 
period between the 90 per cent and the end point be more than 
five minutes. 

The heating shall be continued until the mercury reaches a maxi- 
mum and starts to fall consistently. The highest temperature 
observed on the distillation thermometer shall be ‘recorded as the 
maximum temperature or end point. Usually this pomt will be 
reached after the bottom of the flask has become dry. The 
total volume of the distillate collected in the receiving graduate 
shall be recorded as the recovery. ‘The cooled residue shall be 
poured from the flask into a small cylinder graduated im 0.1 cc, 
measured when cool and the volume recorded as residue. The 
difference between 100 cc and the sum of the recovery and the 
residue shall be calculated and recorded as distillation loss. 

(g) Acipity.—Collect in a test tube the cooled residue from 


the distillation flask (see (f)), add three volumes of distilled water 


and shake the tube thoroughly. Allow the mixture to separate 
and remove the aqueous layer to a clean test tube by means of a 
pipette. Add one drop of a 1 per cent solution of methyl orange. 
No pink or red color should be formed. 


5. BASIS OF PURCHASE. 


(a) Unrr.—Mineral spirits shall be purchased either (1) by 
volume, the unit being a gallon of 231 cubic inches at 15.5° C. 
(60° F-.), or (2) by weight. A gallon of mineral spirits at 15.5° C. 
(60° F.) weighs 6.3 to 6.8 pounds. The exact weight in pounds 
per gallon of any sample can be determined by multiplying the 
specific gravity at 15.5/15.5° C. (60/60° F.) by 8.33. HExample— 
If the specific gravity at 15.5° C. is 0.7642, the weight per gallon 
at this temperature will be 0.7642 X8.33 = 6.366 pounds. When 
purchased by weight, quotations shall be by the pound or by 
the 100 pounds. The request for bids will state whether quota- 
tions shall be by the gallon, pound, or 100 pounds. 

(b) CORRECTION OF VoLUME.—The gallonage paid for shall be 
the volume corrected to a standard temperature of 15.5° C. 


10 Circular of the Bureau of Standards. 


(60° F.). The correction shall be made by deducting from (when 
the temperature of gauging is above 15.5° C.) or adding to (when 
the temperature of gauging is below 15.5° C.) the gallonage as 
gauged. Such deduction or addition shall be computed on the 
basis of a coefficient of expansion of 0.000945 per degree centigrade 
(or 0.000525 per degree Fahrenheit). Example—If the tem- 
perature at which the spirits is gauged is 75° F., and the 
volume delivered (at that temperature) is 8,000 gallons, then 
0.000525 X15 X 8,000 equals the quantity in gallons which must 
be subtracted from 8,000 gallons to give the true gallonage at 
60° F., or, if the temperature at which the spirits is gauged is 
10° C., then 0.000945 X 5.5 X 8,000 equals the quantity in gallons 
which must be' added to the banged volume of 8,000 —— to 
give the true gallonage at 15.5° C. 

(c) CERTIFICATION.~—Mineral spirits delivered in barrels, brew 
or tank cars shall either be accompanied by an official gauger’s 
certificate showing the net contents of each container and also 
the temperature of contents at the time of gauging or shall be 
subject to gauging by the purchaser’s inspector. {n the absence 
of a statement of the temperature at the time of gauging on the 
official gauger’s certificate, or in case the barrels show evidence 
of loss by leakage or other shortage, the delivery shall be subject 
to reinspection and regauging by the purchaser’s inspector. 

WASHINGTON, January 2, 1923. 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 


5 CENTS PER COPY 


PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS 
COPY FOR PROFIT.—PUB. RES. 57, APPROVED MAY 11, 1922 


V.-. 


Eee a ee 


Sab pe 
i. Ca! 


DEPARTMENT OF COMMERCE 


BUREAU OF STANDARDS 


Ss. W. STRATTON, Director 


CIRCULAR OF THE BUREAU OF STANDARDS 
No. 102 


[2d edition. Issued September 22, 1922] 


UNITED STATES GOVERNMENT SPECIFICATION FOR 
COMPOSITE, VEHICLE FOR THINNING SEMIPASTE 
PAINTS WHEN THE USE OF STRAIGHT LINSEED OIL 
IS NOT JUSTIFIED 


FEDERAL SPECIFICATIONS BOARD 
STANDARD SPECIFICATION NO. 17 
This specification was officially adopted by the Federal Specifications Board, 


on February 3, 1922, for the use of the Departments and Independent Establish- 
ments of the Government in the purchase of materials covered by it. 


CONTENTS 

Page 
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1. GENERAL 


_ This specification covers a composite vehicle which contains 
in one liquid drying oil, drier, and volatile thinner. Such prep- 
arations are sometimes called ‘‘ Thinning Mixtures for Paint,” and 
are also offered under a variety of trade names, such as “Japan 
Oil,” “‘ Paint Oil,’ ‘Linseed Oil Substitute,” etc. The last name 
should, however, not be used, for while such materials may have 
decided merit they are not substitutes for linseed oil. 
The composite vehicle must meet the following requirements: 
- APPEARANCE.—Shall be clear and free from suspended matter 
and sediment. 
7787°—22 


2 Circular of the Bureau of Standards 


CoLor.—No darker than a solution of 6 g of potassium dichro- 
mate in 100 cc pure sulphuric acid of specific gravity 1.84. 

Opor.—Not offensive, either in bulk or in its’subsequent use in 
paint mixtures. 

MIXING WITH LINSEED O1L.—When mixed in any proportion 
with pure raw linseed oil meeting the specifications of B. S. Cir- 
cular 82, the resulting mixture shall be clear and shall show no 
separation or precipitation on standing 18 hours: > =; 

DrRYING.—When flowed on glass, the composite vehicle shall 
set to touch in not more than 4 hours and dry hard in not more 
than 6 hours. When mixed with an equal volume of pure raw 
linseed oil, the resulting mixture when flowed<on glass shall set 
to touch in not more than 6 hours and dry hard in not more, than 
8 hours. 

TTOUGHNESS.—The film on glass Bie he 4 Pad 6 hours, at 
105 to 110°C (221 to 230° F) shall be glossy, tough, and elastic. 

NONVOLATILE. MATTER.—Not less than 50 per cent by weight. 

Acip NuMBER.—Not more than 12, calculated ‘to basis of non- 
volatile matter. — Te 

Nortr.—Deliveries will, in general, be sampled and tested by the following methods, 


but the purchaser reserves the right to use any additional available snlormatog to 
ascertain whether the material meets the sey aes on 


2. SAMPLIN G 


It is mutually agreed by buyer, and seller that a single package 
out of each lot of not more than 1000 packages be taken as rep- 
resentative of the whole. Whenever possible an original. un- 
opened container shall be sent to the laboratory, and: when for any 
reason this is not done, the inspector shall thoroughly mix the 
contents of the containers sampled, transfer not less than 1 quart 
to a clean, dry, glass bottle! or'tin can, which must be nearly filled 
with the sample, securely stoppered with a new, clean cork or well- 
fitting cover or cap, sealed, and distinctly labeled by” the in- 
spector. The inspector should take a duplicate from the container 
sampled to hold for check in case of dispute, and when. Tequested 
should take a sample for the seller. 


Fri LABORATORY EXAMINATION’ Or 


(a) APPEARANCE. Fill two test ‘tubes of, ‘the same, size, eq 
cm or 6 inches), with the. thoroughly mixed, sample. to ‘within 
2.5 cm (1 inch) of the top. Stopper the tubes with clean corks. 
Let stand for 24 hours. Note whether sediment is evident in 


Specification for Composite Vehicle 3 


the tubes; if not, shake one tube vigorously and compare the 
two tubes. If they still look alike and the liquid appears clear, 
the sample is considered free from sediment and suspended 
matter. 

(b) CoLor.—Prepare a standard color solution by dissolving 
6 g of pure powdered potassium. dichromate in 100 cc of pure 
concentrated sulphuric acid of specific gravity 1.84. Gentle — 
heat may be used if necessary to perfect the solution of the dichro- 
mate. ‘The standard color solution and a sample of composite 
vehicle to be tested shall be placed in clear, thin-walled glass 
tubes of the same diameter. ‘The color comparison shall be made 
by placing the tubes close together and looking through them by 
transmitted light. The tubes used for this test should be 1.5 
to 2.0 cm (3% to +4 inch) in diameter and shall be filled to a depth 
of at least 2.5 cm ie inch). 

(Since the potassium dichromate-sulphuric acid must be freshly 
made for this color comparison, it is frequently more convenient 
to compare samples with a permanently sealed tube of composite 
vehicle which has previously been found to be slightly lighter im 
color than the standard solution of 6 g dichromate in sulphuric 
acid. When samples are found to be darker than this sealed tube 
of composite vehicle, the dichromate standard should be made up 
for final decision.) 

(c) Opor:—Note the odor of the material in bulk, pour a small 
portion in»a shallow flat-bottomed dish, and allow to stand ex- 
posed to the air for not less than 48 hours: Flow some on a glass 
plate and allow to dry in a vertical position for not less than 48 
hours. Note the odor of these test. portions from time to time. 
A mild odor of wood turpentine or of fish oil should not be cause 
for rejection; but a pronounced offensive odor, either due to very 
crude wood turpentine, rank fish oil, or other offensive substances, 
would be cause for rejection: 

((d) Mrxinc-with LINSEED O1L.—Thoroughly mix 25 cc of the. 
sample with 25 cc pure raw linseed oil and transfer portions of the 
mixture to two similar test tubes which shall be filled to within 
2.5 cm (1 inch) of the top and stoppered with clean corks. 

Thoroughly mix 5 cc of the sample with 45 cc of pure raw lin- 
seed oil and transfer portions of the mixture to two similar test 
tubes, which shall be filled to within 2.5 em (1 inch) of the top and 
stoppered with clean corks. 

Let the four tubes stand for 24 hours and note stag any sediment 
or curdling is apparent in any of the tubes:* If not, shake one tube 


4 Circular of the Bureau of Standards 


of each pair vigorously and then compare with the utishaken tube 
of the same dilution. If the tubes of the same dilution still look 
alike, the sample is considered to mix properly with linseed oil. 

(e) Dryinc.—Pour the undiluted sample and the mixture with 
an equal volume of linseed oil on clean glass plates not less than 
15 cm (6 inches) long and 10 em (4 inches) wide. Place the plates 
in a nearly vertical position in a well-ventilated) room. but not in 
the direct rays of the sun. The temperature of the room should 
be from 21 to 32° C (70 to 90° F). . The films are tested at points 
not less than 2.5 cm (1 inch) from the edges of the films by touch- 
ing with the finger. The material is considered to have set to 
touch when gentle pressure of the finger shows a tacky condition 
but none of the material adheres to the finger. The material is 
considered to have dried hard. when the pressure that cam be ex- 
erted between the thumb and finger does not move the film nor 
leave a mark that remains noticeable after the spot is sdighitly 
polished. 

(f) TouGHNEss.—Pour the undiluted sample on.a be x 
plate. Let drain in a vertical position for 2 minutes, then place 
in a horizontal position, film up, and let stand at room tempeta- 
ture for 2 hours. Then bake at a temperature of 105 to 110° C 
(221 to 230° F) for 6 hours. Remove from the oven and let stand 
at room temperature for not less than 18 hours. The resulting 
film shall be glossy and when tested with a knife blade shall show 
elastic properties, turning up with the blade of the knife in an 
elastic ribbon without cracking or breaking. ‘The film shall also 
stand rapid light rubbing without breaking the surface. puke 

(9) NONVOLATILE MaTrEer.—Place a portion of the sample in 
a stoppered bottle or weighing pipette. . Weigh the container and 
sample. Transfer about 1.5 g of the sample toa weighed flat- 
bottomed metal dish about 8 cm in diameter (a friction-top can 
plug). Weigh the container again and by difference calculate 
the exact weight of the portion of sample transferred to the 
weighed dish. Heat the dish and contents in an oven maintained 
at 105 to 110° C (221 to 230° F) for 3 hours. Cool and weigh. 
From the weight of the residue left in the dish and weight of the 
sample taken calculate the percentage of nonvolatile matter. 

(1) Actb NuMBER.—Place a portion of the sample in a stop- 
pered bottle or weighing pipette. Weigh the container and 
sample. Transfer an amount corresponding to between 1 and 2 g 
of nonvolatile matter (see (g)) to a 200 ce Erlenmeyer flask, 
reweigh the container and calculate the exact weight taken, add 


Specification for Composite Vehrcle 5 


25 cc of neutral pure benzol and 25 cc of neutral ethyl alcohol, or 
ethyl alcohol denatured with pure benzol or pure methyl alcohol. 
(The alcohol used in all cases must be neutral.)« Boil for 30 
minutes. (It is best to use a reflux condenser.) Cool to room 
temperature, add 4 drops of phenolphthalein indicator solution, 
and titrate with standard alcoholic sodium hydroxide. From 
the number of cubic centimeters of standard hydroxide solution 
calculate the acid number to the basis of the nonvolatile resi- 
due. (Acid number is milligrams of KOH required to neutralize 
acid in 1 g of material tested.) 


4. REAGENT 


ALCOHOLIC SODIUM HypROXIDE SOLUTION.—Dissolve pure so- 
dium hydroxide in 95 per cent ethyl alcohol in the proportion of 
‘about 22 g per 1oooce. Let stand ina stoppered bottle. Decant 
the: clear liquid into another bottle and keep well stoppered. 
Standardize against half normal sulphuric or hydrochloric acid, 
using phenolphthalein as indicator. This standardization must 
be made each day that the solution is used. 

This solution should be colorless or only slightly yellow when 
used, and it will keep colorless longer if the alcohol is previously 
treated with sodium hydroxide (about 80 g to 1000 cc) kept at 
about 50° C for 15 days and then distilled. 


5. BASIS OF PURCHASE 


Composite vehicle shall be purchased by volume, the unit being 
a gallon of 231 cubic inches at 15.5° C (60° F). The volume may 
be determined by measure or, in case of large deliveries, it may 
be easier to determine the net weight and specific gravity at 
15.5/15-5° C (60/60° F) of the delivery. The weight per gallon in 
pounds can then be determined by multiplying the specific grav- 
ity by 8.33. The net weight in pounds divided by the weight 
per gallon gives the number of gallons. 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 


5 CENTS PER COPY 
V 


WASHINGTON : GOVERNMENT PRINTING OFFICB : 1922 


4 


U. S. Gov't 
Master 
Specification 


No. 18b 


DEPARTMENT OF COMMERCE 


BUREAU OF STANDARDS 


George K. Burgess, Director 


CIRCULAR OF THE BUREAU OF STANDARDS, No. 103 


[4th ed., issued October 5, 1926] 


UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
VARNISH, SPAR, WATER-RESISTING 


FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 18b 
[Revised August 7, 1926] 


This specification was officially promulgated by the Federal Specifications 
Board on February 3, 1922, for the use of the departments and independent 
establishments of the Government in the purchase of water-resisting spar 
varnish. ’ 

[The latest date on which the technical requirements of this revision shall become mandatory for all 


departments and independent establishments of the Government is November 7, 1926. They may be 
put into effect, however, at any earlier date; after promulgation.] 


CONTENTS 


A) 
) 
3 


III. Material and workmanship. ---------------------------------- 
IV. General requirements ---------------------------------------- 
V. Detail requirements----------------------------------------- 
VI. Methods of sampling, testing, and basis of purchase------------- 
1. Sampling. -...-.------------------------------------- 

2. Laboratory examination_-_-_._-------------------------- 

3. Basis of purchase_------------------------------------ 

Wit, Packing ..........-------.--.---+-------------+--+------+-- 
WHIT. Notes... <.-2------ 2 ee ee ong sen 5 5 ee 8 


I. GENERAL SPECIFICATIONS 


DaOoOwns NNW WN KF 


There are no general specifications applicable to this specification. 
Il. GRADE 


Water-resisting spar varnish for general use shall be of one grade 
only, as hereinafter described. 
10414°—26t 


2 CIRCULAR OF THE BUREAU OF STANDARDS 
Ill. MATERIAL AND WORKMANSHIP 


The manufacturer is given wide latitude in the selection of raw 
materials and processes of manufacture so that he may produce 
varnish of the highest quality. 


IV. GENERAL. REQUIREMENTS 
There are no general requirements applicable to this specification. 
V. DETAIL REQUIREMENTS | 


1. AppEARANCE.—Clear and transparent. 

2. Conor.—Not darker than a solution of 3 g of potassium dichro- 
mate in 100 cc._of puresulphuric acid, specific — 1.84. 

. Fuasu Pornt (Ciosep-Curp).—Not below 30° C. (85° F.). 

. Nonvouatite Marter.—Not less than 45 a cant by Mesias 

. Ser ro Toticx.—In not more than five hours.:' | 

. Dry Harp anv Tovucu.—In not more than 24 hours. 

. Viscosiry.—Not less than 1.40 nor more than 2.25 poises. _ 

. Worxine Propertius.—Varnish shall have good. brushing, 
flowing, covering, and. leveling properties... The dried film shall 
‘have the characteristic gloss of spar varnish. rinieey: 

9. Saretry of Worxinc.—Shall pass the draft test. 

10. Water ReststAncze.—Dried film shall withstand gold water 
for 18 hours and boiling water for 15 minutes without whitening 
or dulling. 

11. ToucHuness.—Shall pass a 50>per cent kauri reduction test 
af 24° Oo(T 5 a), 


ee SS ee 


VI. METHODS OF SAMPLING, TESTING, AND BASIS ee 
PURCHASE : | 


tj - 


Deliveries will, in general, be sampled and tested by the one 
methods, but the purchaser reserves the right to use any additional infor- 
mation to ascertain whether the material meets the specification. 


1. SAMPLING 


It is mutually agreed by buyer and seller that a single package 
out of each lot of not. more than 1,000, packages will be taken as 
representative of the whole. Whenever possible an original unopened 
container shall be sent to the laboratory, and when for any reason 
this is not done the inspector shall thoroughly mix the contents 
of the container sampled, transfer not less than 1 quart to a clean 
dry glass bottle or tin can, which must be nearly filled with the 
ight Fy securely stoppered with a new clean cork or well-fitting 
cover or cap, sealed, and distinctly labeled by the inspector. The 


SPECIFICATION FOR SPAR VARNISH 3 


inspector should take a duplicatefrom the container sampled to be held 
for check in case of dispute, and, when requested, should take a 
sample for the seller. 


Zz. LABORATORY EXAMINATION 


The tin panels used in the following tests shall all be cut from 
bright tin plate weighing not more than 25 g nor less than 19 ¢g 
per square decimeter (0.51 to 0.39 pound per square foot). (Com- 
mercial No. 31 gauge bright tin plate should weigh about 0.44 
pound per square foot. It is important that the tin plate used shall 
be within the limits set.) The panels shall be about 7.5 by 13 cm 
(8 by 5 inches) and must be thoroughly cleaned with benzol imme- 
diately before using. 

(2) AppraARANCcE.—Pour some of the thoroughly mixed sample 
into a clear glass bottle or test tube and examine by transmitted 
light. The varnish must be clear and transparent. 

(b) Cotor.—Prepare a standard color solution by dissolving 3 g 
of pure powdered potassium dichromate in 100 cc of pure concen- 
trated sulphuric acid of specific gravity 1.84. Gentle heat may be 
used if necessary to perfect the solution of the dichromate. The 
standard color solution and a sample of the varnish to be tested 
shall be placed in clear thin-walled glass tubes of the same diameter. 
The color comparison shall be made by placing the tubes close. to- 
gether and looking through them by transmitted light. The tubes 
used for this test should be 1.5 to 2.0 cm (5% to +4 inch) in diameter 
and shall be filled to a depth of at least 2.5 em (1 inch). (Since the 
potassium dichromate-sulphuric acid must be freshly made for this 
color comparison, it is frequently more convenient to compare sam- 
ples with a permanently sealed tube of varnish which has previously 
been found to be slightly lighter in color than the standard solution 
of 3 g dichromate in sulphuric acid. When samples are found to be 
darker than this standard tube of varnish, the dichromate standard 
should be made up for final decision.) 

(c) Fuasa Point.—Determine with either the Tag or Elliott closed- 
cup tester. The former is preferred.’ 

(d) NonvouatTiteE Matrrer.—Place a portion of the sample in a 
stoppered bottle or weighing pipette. Weigh container and sample. 
Transfer about 1.5 g of the sample to a weighed flat-bottomed metal 
dish about 8 cm in diameter (a friction-top can plug). Weigh con- 
tainer again and by difference calculate the exact weight of the por- 
tion of sample transferred to the weighed dish. Heat dish and 
contents in an oven maintained at 105 to 110° C. (221 to 230° F.) 
for three hours. Cool and weigh. From the weight of the residue 


1 Directions for using the Tag tester may be found in A. S. T. M. Standards D 56-21, and directions 
for using the Elliott cup in Proceedings A. S. T. M., 1917, part 1, p. 414. 


4 CIRCULAR OF THE BUREAU OF STANDARDS 


left in the dish and weight of the sample taken calculate the per- 
centage of nonvolatile residue. 

(e) Sertine To Toucn AND Dryine Timu.—Pour the varnish on 
one of the tin panels described above. Place the panel in a nearly 
vertical position in a well-ventilated room but not in the direct 
rays of the sun. The atmosphere of this room must be free from 
products of combustion or laboratory fumes. The temperature of 
the room should be from 21 to 32° C. (70 to 90° F.). The film is 
tested at points not less than 2.5 cm (1 inch) from the edges of the 
film by touching lightly with the finger. The varnish is considered 
to have set to touch when gentle pressure of the finger shows a tacky 
condition but none of the varnish adheres to the finger. The var- 
nish is considered to have dried hard when the pressure that can be 
exerted between the thumb and finger does not move the film or 
leave a mark which remains noticeable after the spot is lightly 
polished. If rapid light rubbing breaks the surface, the sample is 
considered not to have satisfactorily dried hard. In case the test 
shows time of setting to touch or drying hard more than 5 and 24 
hours, respectively, two additional tests shall be run on different 
days, and if the varnish does not meet the above drying and harden- 
ing requirements on both of these additional tests it shall be con- 
sidered unsatisfactory. In cases where different laboratories fail to 
agree on the drying test, due to different atmospheric conditions, 
and umpire tests are necessary, such tests shall be made in a well- 
ventilated room maintained at a temperature of 70° F. and relative 
humidity of 65 per cent saturation. — ne 

(f) Viscosrry.—Determine the viscosity of the varnish by compari- 
son at 25° C. (77° F.) with secondary standards whose viscosity ex- 
pressed in poises has been accurately determined at that temperature.’ 
- (g) Worxine Proprrtizs.—Coat a smooth clean panel of metal 
or wood with the sample, using a good varnish brush. Observe 
whether the varnish shows objectionable “pulling” under the brush 
and whether the varnish film levels and yields a surface of good — 
appearance. Br 
f(h) Savery or Worxine.—Draft test—Flow the varnish on one 
of the standard tin panels and immediately place the panel in the — 
direct draft of a small (8 or 10 inch) electric fan running at full 
} speed. The panel should be placed approximately 2 feet from the 
fan in a nearly vertical position and at an angle of 45° to the line of 
the air current. Allow the panel to remain in this position for five 
hours, remove, and allow to harden overnight. The-varnish shall 
show no dulling, crow’s footing, or frosting, This. test shall be 


et 


ardner-Holdt tubes may be used, in which case the limits are tube “F’” to ok Paid inclusive. * See Ph 
Circular No. 178, Srientific Section, Paint Manufacturers’ Association of the United States. eaelin tig 

. Lt ate: 2) scnlgeitig. rire, 

5 anit yectaagae ot 


a 


SPECIFICATION FOR SPAR VARNISH 5 


made under the same room and temperature conditions noted under 
‘Setting to touch and drying time,” Section VI, 2, (€). suns" 
_. (i) Warr Resistance.—Pour the varnish Sn two of the tin 


“panels described above and allow to dry under the conditions de- 


scribed in paragraph (e) for 48 hours. Place one of these panels 
in a beaker containing about 2.5 inches of distilled water at room 


temperature (immersing the end of the panel which was upper- 


most during the drying period) and leave in water for 18 hours. 
The varnish shall show no whitening and no more than very slight 
dulling either when observed immediately after removing from 
the water or after drying for two hours. Place the other panel 


in a beaker containing about 2.5 inches of boiling distilled water 


(immersing the end of the pane! which was uppermost during the 
drying period) and allow to remain in the boiling water for 15 


‘minutes. The varnish shall show no whitening and no more than a 


very slight dulling either when observed immediately after removing 
from the water or after drying for two hours. 

(j) Touauness.—The toughness of the varnish is determined by 
the Kauri reduction test, as follows: By proportionately reducing its 
toughness by the addition of s standard solution of “run-Kauri” 
gum in pure spirits of turpentine. 

(1) Preparation of the “run Kauri.”—Arrange a distillation flask, 
water-cooled condenser, and a tared receiver on a balance. Place 
in the flask about one-third of its volumetric capacity of clear, 
bright hard pieces of Kauri gum broken to pea size. Carefully melt 
and distill until 25 per cent by weight of the gum taken is collected 
in the tared receiver. Pour the residue into a clean pan and when 
cold break up into small pieces. | 

(2) Preparation of standard “run Kauri” solution—Place a 
quantity of the small broken pieces of run Kauri, together with 
twice its weight of freshly redistilled spirits of turpentine, using only 


- that portion distilling over between 153 and 170° C. (308 and 338° F.) 
in a carefully tared beaker. Dissolve by heating to a temperature 
‘of about 149° C. (300° F.) and bring back to correct weight when 
cold by the addition of the amount of redistilled spirits of turpentine 


necessary to replace the loss by evaporation during the dissolving of 
the gum. 

(3) Reduction of the varnish.—Having carefully determined the 
nonvolatile content of the varnish according to the method under 
paragraph (d) of this specification, take 100 g of the varnish and 
add to it an amount of the standard run-Kauri solution equivalent to 
50 per cent, by weight, of the nonvolatile matter in the varnish. 
Mix the varnish and the solution thoroughly. 

(4) Application of the varnish—Flow a coat of the varnish thus 
reduced on one of the tin panels described above and let stand in a 


6 CIRCULAR OF THE BUREAU OF STANDARDS 


nearly vertical position at room temperature for one hour. Next 
place the panel in a horizontal position in a properly ventilated oven 
and bake for five hours at 95 to 100° C. Remove the panel from the 
oven and allow to cool at room temperature, preferably 24° C. 
(75° F.) for one-half hour. 

(5) Bending the panel.—Place the panel with the varnished side 
uppermost over a 3 mm (-inch) rod, held firmly by suitable sup- 
ports, at a point equally distant from the top and bottom edges of the 
panel and bend the panel double rapidly. The varnish must show 
no cracking whatsoever at the point of bending. For accurate results 
the bending of the panel should always be done at 24° C. (75° F.), 
for a lowering of the temperature will lower the percentage of reduc- 
tion that the varnish will stand without cracking, while an increase 
in the temperature increases the percentage of reduction peer the 
varnish will stand. 


3. BASIS OF PURCHASE > 


Varnish shall be Regohenel by volume, the unit edad a allen of 
231 cubic inches at 15.5° C. (60° F.). The volume may be deter- 
mined by measure, or, in case of large deliveries, it may be easier to 
determine the net weight and specific gravity at 15.5/15.5° C. 
(60/60° F.) of the delivery... The weight per gallon in pounds can 
then be determined by multiplying the specific gravity by 8.33. 
The net weight in pounds divided by the weight per enrer gives the 
number of gallons. 


vit. PACKING 


Packing shall be in accordance with commercial practice unless 
otherwise specified. | | 


VIII. NOTES 


_ Water-resisting spar varnish is intended to meet all the needs of 
the Government for a general utility varnish, suitable for both out- 
side and inside exposure, where durability is the chief requisite and 
where high gloss or initial hardness of the film are not required. 
It does not, however, fulfill all the requirements for an aircraft varnish. 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
esi ae D. C. 


& CENTS PER COPY 
Vv 


F. 


“se 


a3 


ae 


Pe Gecaran? 8 


Page 
v5 a : 


DEPARTMENT OF COMMERCE. 


BUREAU OF STANDARDS. 


CIRCULAR OF THE BUREAU OF STANDARDS. 
No. 104. 


[2d Edition. Issued January 30, 1923.] 


UNITED STATES GOVERNMENT SPECIFICATION FOR 
ASPHALT VARNISH. 


Gene 


FEDERAL SPECIFICATIONS BOARD. 
STANDARD SPECIFICATION No. 19. 


[Revised January 2, 1923.] 


This specification was officially adopted by the Federal Specifications Board 
on February 3, 1922, for the use of the departments and independent establish- 
ments of the Government in the purchase of asphalt varnish. 


CONTENTS. 
Page 
IN ee i eh ig welatne He da CNR E Phe Gen bn Ces es 9 ee I 
rane laa to) a2. Ns Sa eas EO RRA BE, a. . ie OT EAS Be 2 
3. Laboratory examination..............-.s eee cece ete nett eee n eee ee tenes 3 
4; Basis of purchases; 0). 05 5G. i eb ee ee ae RETR ee peewee tle ns 7 
1. GENERAL. 


This varnish shall be composed of a high grade of asphalt 
fluxed and blended with properly treated drying oil and thinned 
to the proper consistency with a volatile solvent. It must be 
resistant to air, light, lubricating oil, water, and, when the con- 
tract so specifies, to mineral acids of the concentration herein- 
after specified. It must meet the following requirements: 

APPEARANCE.—Smooth and homogeneous; no livering or 
stringiness. 

CoLor.—Jet black. 

FLsasH Pornt (CLosED-Cup).—Not below 30° C. (86° F.). 

27817°—23 


2 Circular of the Bureau of Standards. 


ACTION WITH LINSEED O1L.—Varnish must mix readily to a 
homogeneous mixture with an equal volume of raw linseed oil. 

MATTER INSOLUBLE IN CARBON BISULPHIDE.—Not more than 
I per cent. 

NONVOLATILE MATTER. i less than 40 per Sent by weight. 

Fatry MaTrer.—Not less than 20 per cent of the nonvolatile. 
Must be liquid and not show a violet coloration by the Liebermann- 
Storch test. : | 

Set To ToucH.—Within 5 hours. 

Dry Harp AnD JouGcH.—Within 24 hours. 

TouUGHNESS.—Film.on metal. must withstand rapid bending 
over a rod 3 mm (% inch) in diameter. 

WorkiNG PRropERTIES.—Varnish must heve good brushing, 
flowing, covering, and leveling properties. 

RESISTANCE TO WATER.—Dried film must withstand cold water 
for 18 hours. : 

RESISTANCE ‘TO Or.—Dried film’ must ‘withstand lubricating 
oil for 6 hours. 

RESISTANCE TO MINERAL AcIDs. '_Dried film must withstand 
action of the following acids for six hours: Sulphuric acid, specific 
gravity 1.25 (about 33 per cent), Nittie acid, specific’ ‘gravity 
1.12 (about 20 per cent). Hydrochloric acid; specific gravity 
1.09 (about 18 per cent). i , a 

NotE.—Deliveries will, in general, be sampled and tested by the following methods, 


but the purchaser reserves the right to use any additional available information to 
ascertain whether the material meets the specification. 


2. SAMPLING. 


7 
soe ie Pe h 


It is mutually agreed by buyer and seller that a press pealialics 
out of each lot of not more than 1,000 packages be taken as repre- 
sentative of the whole. Wherever possible, an original unopened 
container shall be sent to the laboratory. When for any reason this 
can not be done, the inspector shall select a package and thoroughly 
mix its contents... He shall fill a 1 quart, clean, dry. container from 
this package, securely stopper it witha new. clean: cork or, well- 
fitting cover.or. cap, seal, and distinctly ; label it, The. inspector 
shall take a duplicate from,the container sampled to, be. held for 
check in case of dispute, and, when requested, shall take a eels 
for the seller. 


1 Only required when the contract specifically demands asphalt varnish that is resistant to mineral acids. 


Specification for Asphalt Varnish. 3 
3. LABORATORY EXAMINATION. 


(a) APPEARANCE AND CoLor.—Pour some of the thoroughly 
mixed sample on a clean, clear glass plate and stand in a vertical 
position until the excess varnish has drained off. Examine the 
film by transmitted light. The-varnish must be smooth and 
homogeneous and must not show any separation or segregation 
of the constituents. Examine the film by reflected light. The 
_ film must be jet black in color. 

(6) Fiass Point,—Determine with either the ‘Tag’ or 
Elliott closed-cup tester. The former is preferred.’ 

(c) ACTION wiTtH LINSEED O1L.—Pour 10 cc of the varnish 
into a test tube and add an equal volume of raw linseed oil con- 
forming to Bureau of Standards Circular No. 82. Stopper the 
test tube and shake vigorously for several minutes. Then pour 
some of the mixture on a clear glass plate and stand in a vertical 
position. After the excess varnish has drained off examine the 
film by transmitted light. There shall be no separation of the 
oil and varnish. 

__ (d) Matrer INSOLUBLE IN CARBON one e —Weigh about 

5 g of the varnish into a small beaker, add 25 cc of carbon bisul- 
ae and allow to stand for 15 minutes. Filter through a 
weighed Gooch crucible, prepared with a medium thick mat of 
asbestos, using suction if necessary to aid in filtration. Wash 
the residue in the crucible with carbon bisulphide until the wash- 
ings are colorless. Dry in air at room temperature until the odor 
of carbon bisulphide has almost disappeared, and then for one 
_ hour in an oven at 110°C. Cool and weigh. From the weight of 
the insoluble left in the crucible and the weight of sample taken 
calculate the percentage of insoluble in carbon bisulphide. 

(ec) NONVOLATILE MaTTEeR.—Place a portion of the sample in a 
stoppered bottle or weighing pipette. Weigh the container and 
sample. Transfer about 1.5 g of the sample to a weighed flat- 
bottomed metal dish about 8 cm in diameter (a friction-top can 
plug). Weigh the container again and by difference calculate the 
exact weight of the portion of sample transferred to the weighed 
dish. Heat the dish with its contents in an oven maintained at 
-to5 to 110° C. for three hours. Cool and weigh. From the 
weight of the residue left in the dish and the weight of the sample 
taken calculate the percentage of nonvolatile residue. 


2 Directions for using the “’Tag’”’ tester may be found in A. S. T. M. Standards Ds56-21, and directions 
for using the Elliott cup in Proceedings A. S. T. M., 1917, pt. 1, D. 414. 


f 


“ 


t* 


4 Circular of the Bureau of Standards. 


(f) Fatry Matrer.—Weigh about 5 g of the varnish into a 
wide-mouthed flask, add 50 ce of benzol and 5 g of clean, fine 
silica sand and heat under a reflux condenser on a steam bath 
until the varnish is entirely dissolved. Add 25 cc of ethyl alcohol 
denatured with methyl alcohol and 25 cc of a 0.5 N alcoholic 
caustic soda solution and continue boiling under the reflux con- 
denser for one-half hour. Remove the condenser and evaporate 
the solution to dryness. Add to the residue in the flask 50 cc of 
distilled water and heat until the residue is disintegrated. Filter 
the water solution of the soaps. Repeat this operation with 25 
cc portions of water until the residue is completely disintegrated 
and the wash water is clear and colorless. 

Combine the filtrates (the soap solution and washings), deidity 
with hydrochloric acid, and heat until the fatty acids and any 
emulsified asphalt separate and rise to the top and the water 
below is clear. Cool, transfer to a separatory funnel, and extract 
three times with 25 cc portions of ether. Combine the ether ex- 
tracts and wash with water until free from acid. Filter the ether 
extracts through paper into a beaker and wash the residue on the 
paper with ether until the washings run through colorless. Evap- 
orate the ether solutions to dryness. 

Add ro to 15 ce of 95 per cent ethyl alcohol to the residue in 
the beaker and warm on the steam bath. Cool to room tempera- 
ture and filter through paper into a tared flask or dish. Repeat 
this operation with 5 cc portions of 95 per cent ethyl alcohol 
until the alcohol remains colorless. Finally wash the residue on 
the paper with 95 per cent ethyl alcohol until the washings run 
through colorless. Evaporate the alcoholic solution to dryness on 
a steam bath and heat for an hour in an oven at 105° C. (221° F.). 
Cool and weigh. From the weight of the residue in the flask and 
the weight of the original sample calculate the percentage of fatty 
matter. ‘ei 

(Sometimes the residue obtained after saponification and the 
evaporation of the benzol and alcohol from the saponifying mix- 
ture is not completely disintegrated by boiling with water. In 
that case extract with water until nothing further dissolves and 
then dry. Dissolve in benzol, using heat if necessary, and wash 
the benzol solution several times with water. Heat the washings 
until the odor of benzol has disappeared and add to the be 2 
solution before acidifying.) 

The fatty matter obtained above must be a clear amber aioe 
liquid. A fugitive violet color shall not be obtained when the 


_ Specification for Asphalt Varnish. 5 


fatty matter is subjected to the following test: Dissolve a small 
amount of the fatty matter in 5 cc of acetic anhydride, warming 
if necessary to aid solution. Cool, draw off the acetic anhydride 
solution, and add a drop of sulphuric acid, 1.53 specific gravity. 

-(g) Dryinc Trme.—Pour the varnish on a clean glass plate 
not less than 15 em (6 inches) long and 10 cm (4 inches) wide. 
Place the plate in a nearly vertical position in a well-ventilated 
room, but not in the direct rays of the sun. The temperature of 
the room should be from 21 to 32° C. (7o to 90° F.). Test the 
film at points at not less than 2.5 cm (1 inch) from the edges of the 
film by touching lightly with the finger. The varnish is considered 
to have set to touch when gentle pressure of the finger shows a 
tacky condition, but none of the varnish adheres to the finger, 
The varnish is considered to have dried hard when the pressure 
that can be exerted between the thumb and finger does not move 
the film or leave a mark which remains noticeable after the spot 
is lightly polished. If rapid light rubbing breaks the surface, the 
sample is not considered to have satisfactorily dried hard. In 
case the test shows time of setting to touch or drying hard more 
than 5 and 24 hours, respectively, two additional tests shall be 
run on different days, and if the varnish does not meet the above 
drying and hardening requirements on both of these additional 
tests it shall be considered unsatisfactory. In cases where dif- 
ferent laboratories fail to agree on the drying test, due to different 
atmospheric conditions, and umpire tests are necessary, such tests 
shall be made in a well-ventilated room maintained at a tempera- 
ture of 70° F. and relative humidity of 65 per cent saturation. 

(h) Toucuness.—Flow the varnish on one side of a dry steel 
plate that has previously been cleaned of all scale, rust, and grease. 
This plate should be about 0.4 mm (0.016 inch) thick, and 10 by 
15 cm (4 by 6 inches) will be found of convenient size. Let the 
test piece dry in a vertical position, not in the direct rays of the 
sun, in a well-ventilated room at a temperature not below 21° C. 
(70° F.) for a period of not less than six days. _Now bring the 
test piece to a temperature between 21 and 24° C. (70 to 75° F.) 
and, with the varnish film on the outside, bend rapidly over a rod 
3 mim (% inch) in diameter. The film must show no evidence of 
cracking or flaking. 

(t) WORKING PROPERTIES.—A clean piece of steel plate similar 
to that used for testing the toughness of the varnish shall be used 
for determining the working properties. The plate shall be 
thoroughly cleaned of all grease and rust and dried. It shall 


> ) 
- oF 
ne, | 


6 Circular of the Bureau of Standards. 


then be laid in a horizontal position and one coat of the varnish 
applied by brushing. The varnish shall work easily under the 
brush, showing no tendency to draw or pull, and shall flow out 
to a smooth, glossy, jet-black film, free from brush marks, blisters, 
pinholes, or other defects. Test pieces prepared in the above 
manner and allowed to dry in a horizontal position, not in the 
direct rays of the sun, in a well-ventilated room, at a temperature 
not below 21° C. (70° F.) for a period of not less than six days; 
shall be used for testing the resistance of the varnish to cold water 
and lubricating oil. 
(j) RESISTANCE TO WaTER.—A test piece, prepared and dried 
as under (i), shall be inclined at an angle of 45° to the vertical, 
and a gentle stream of cold tap water with a temperature of 
about 25° C. (77° F.) allowed to flow for 18 hours down the middle 
of the varnished surface. After wiping off with a soft cloth or 
chamois skin any deposit due to the tap water the varnish must 
show no whitening, dulling, softening, or other visible defects. 
(k) RESISTANCE TO LUBRICATING O1L.—A test piece prepared 
and dried as under (i) shall be laid flat, and in at least two different 
places several drops of locomotive engine lubricating oil * allowed 
to stand in contact with the film for six hours. During the test 
the spots of oil shall be covered with small watch glasses. After 
wiping off the oil with cotton waste no softening or other deteri- 
oration of the film due to the lubricating oil “shall be perceptible. 


(1) RESISTANCE TO MINERAL Acitp.—A piece of dry, steel plate 3 


free from scale, rust, and grease shall be used for this test. It 
shall be laid in a horizontal position and one coat of the varnish 
applied by brushing. This coat of varnish shall then be allowed 
to dry for 24 to 48 hours, when a second coat shall be applied. 
The second coat shall be allowed to dry, as in (2), for a period of 
not less than six days before testing. The test pieces shall then 
be laid flat and in different places several drops each of sulphuric 
acid, specific gravity 1.25, nitric acid, specific gravity 1.12, and 
hydrochloric acid, specific gravity 1.09, shall be allowed to remain 
on the surface of the film for six hours at room temperature, 
about 21° C. (7o° F.). During the test the drops of acid shall be 


covered with small watch glasses to prevent evaporation. After 


six hours the acid shall be washed off with tap water, and after 
drying for one hour the spots previously in contact with the acid 
examined. They shall show no appreciable change in hardness. 


8 A straight mineral oil having a viscosity (Saybolt Universal) of about a sec. at 210° F. ; 


bs 
a 
BS 


Specification jor Asphalt Varnish. 7 


The film shall then be allowed to dry for 12 hours, when it shall 
again be examined. ‘The spots exposed to the acid shall show 
no disintegration or browning, and their luster shall not be im- 
paired. A slight bloom around the area of the spot exposed to 
the acid shall not be considered an indication of failure. The 
film shall then be removed with carbon tetrachloride, chloroform, 
or carbon bisulphide and the metal examined. It shall show no 
corrosion. 
4. BASIS OF PURCHASE. 


Asphalt varnish shall be purchased by volume, the unit being 
a gallon of 231 cubic inches at 15.5°C. (60° F.). The volume may 
be determined by measure or, in case of large deliveries, it may be 
easier to determine the net weight and specific gravity at 15.5/15.5° 
C. (60/60° F.) of the delivery. The weight per gallon in pounds 
can then be determined by multiplving the specific gravity by 
8.33. The net weight in pounds divided by the weight per gallon 
gives the number of gallons. 

WASHINGTON, January 2, 1923. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 


AT 
5 CENTS PER COPY 


PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS 
COPY FOR PROFIT.—PUB. RES. 57, APPROVED MAY 11, 1922 


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DEPARTMENT OF COMMERCE. 
BUREAU OF STANDARDS. 
S. W. STRATTON, Director 


CIRCULAR OF THE BUREAU OF STANDARDS. 


No. 105. 


[2d edition. September 18, 1922.] 


UNITED STATES GOVERNMENT SPECIFICATION FOR 
LIQUID PAINT DRIER. 


FEDERAL SPECIFICATIONS BOARD. 
STANDARD SPECIFICATION No. 20 


This specification was officially adopted by the Federal Specifications Board on 
February 3, 1922, for the use of the departments and independent establishments of 
the Government in the purchase of materials covered by it. 


CONTENTS. 
Page. 
TORTIE TAL: oo... TN CANARD AIA PIAA. ARN, FbTt EE D I 
RIN eds Sota. SSS a ee ERROR «wid he's WRG TY aN ee Ee 2 
ai areioryextiavinntion. 42.00/57. . Cee ie ee 2 
eam Ol HICCHISe 0.) «nas actrees -arld - te pogidis - Ped: UEP Acie aa 4 
1. GENERAL. 


This specification applies both to straight oil drier—that 1s, 
material free from resins or ‘‘gums’’—and to Japan drier; that is, 
material containing varnish ‘‘gums.”’ 

The drier shall be composed of lead, manganese, or cobalt, or 
a mixture of any of these elements combined with a suitable fatty 
oil, with or without resins or ‘‘gums,’’ and mineral spirits or tur- . 
pentine, or a mixture of these solvents. It shall be free from 
sediment and suspended matter. The drier when flowed on metal 
and baked for 2 hours at 100° C. (212° F.) shall leave an elastic 
film. ‘The flash point shall be not lower than 30° C. (85° F.) when 
tested in a closed-cup tester. It shall mix with pure raw linseed 

7789°—22 


2 C ircular of the Bureau of Standards 


oil in the proportion of 1 volume of drier to 19 volumes of oil with- 
out curdling, and the resulting mixture when flowed on glass shall 
dry in not more than 18 hours. When mixed with pure raw lin- . 
seed oil in the proportion of 1 volume of drier to 8 volumes of oil, 
the resulting mixture shall be no darker than a solution of 6 g of 
potassium dichromate in 100 ce of pure sulphuric acid of specific 
gravity 1.84. ) 

Notr.—Deliveries will, in general, be sampled and tested by the following meth- 


ods, but the purchaser reserves the right to use any additional available information 
to ascertain whether the material meets the specification. 


2. SAMPLING, 


It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1,000 packages be taken as repre- 
sentative of the whole. Whenever possible, an original unopened 
container shall be sent to the laboratory, and when for any reason 
this is not done, the inspector shall thoroughly mix the contents 
of the container sampled, transfer not less than 1 quart to a clean, 
dry glass bottle or tin can which must be nearly filled with the 


sample, securely stoppered with a new clean cork or well-fitting 


cover or cap, sealed, and distinctly labeled by the inspector. The 
inspector should take a duplicate from the container sampled to be 
held for check in case of dispute, and, when requested, should take 
a sample for the seller. 


3. LABORATORY EXAMINATION. 


(a) SEDIMENT AND SUSPENDED MATTEerR.—Thoroughly mix the 
sample. Full two test tubes of the same size (15 cm, or 6 inches) 
to within 2.5 cm (1 inch) of the top with the sample. Stopper 
the tubes with clean corks. Let stand for 24 hours. Note 
whether sediment is evident in the tubes; if not, shake one tube 
vigorously and compare the two tubes. If they still look alike, 
the sample is considered free from sediment and suspended matter. 

(6) CoLoR.—Mix 2 ce drier and 16 cc clear pure raw linseed oil 
that complies with the specifications of B. S. Circular No. 82. Dis- 
solve 6 g of pure powdered potassium dichromate in roo ce of pure 
concentrated sulphuric acid (specific gravity 1.84). Gentle heat 
may be used if necessary to secure a perfect solution of the di- 
chromate. ‘This solution should be freshly prepared. ‘The color 
comparison shall be made by placing the 1:8 drier-linseed oil mix- 
ture and the dichromate-sulphuric acid solution in thin-walled 
glass tubes of the same diameter, 1.5 to 2 cm (5% to 43% inch) to 


U. S. Government Specifications for Laquid Pawnt Drier. 3 


depths of at least 2.5 em (1 inch) and comparing the depth of 
color by looking through the tubes across the column of liquid by 
transmitted light. . 

(c) MixiInc witH LInsEED OIL, SETTING ‘To Toucu, AND 
Dryinc.—Mix 1 ce of the sample and 1g cc of clear pure raw 
linseed oil that complies with the specifications of B. S. Circular 
No. 82. Thoroughly clean a glass plate, finally washing with 
benzol and drying. Pour a portion of the mixture of linseed oil 
and drier over this plate and place the plate in a vertical position 
in a well-ventilated room, the atmosphere of which is free from 
products of combustion or laboratory fumes. Allow the remainder 
of the mixture to stand for 2 hours. No sediment or precipitate 
should appear. At 1-hour intervals examine the film of oil on 
the plate by touching it lightly with the finger at points not less 
than 2.5 cm (1 inch) from the edges. If the film still has the 
greasy feel of fresh linseed oil, it has not set to touch. If the film 
feels tacky and adheres to the finger, it is considered to have set 
to touch. If the finger can be drawn lightly across the film with- 
out the oil sticking to the finger or the surface being marred by 
this treatment, the oil is considered dry. In case the test shows 
time of setting to touch or drying greater than 8 and 18. hours, 
respectively, a second test shall be run on a different day and the 
average of the two tests taken. 

(2) NaTuRE oF BAKED Fitm.—Thoroughly clean with benzol a 
piece of bright sheet metal, either bright sheet iron, tin plate, or 
terneplate. Shake the sample of drier thoroughly and flow enough 
on the plate so that a space at least 7.5 em (3 inches) wide is cov- 
ered. Allow the plate to stand in a vertical position at room tem- 
perature for 30 minutes and then hang in an oven at a temperature 
of 100 to 105° C. (212 to 221° F.) for 2 hours. 

Remove the plate from the oven and allow it to stand at room 
temperature for not less than 1 hour. ‘Test the film of drier with 
a knife blade at a point not less than 2.5 cm (1 inch) from the edge. 
If the film powders or particles fly under the knife blade, it will be 
considered brittle, which will be cause for rejection. 

(e) FLasuH Pornt.—Determine with either the “Tag” or Elliott 


closed-cup tester. The former is preferred.' 
NN ee ee ee a 


1 Directions for using the Tag tester may be found in A.S. I’. M. Standards D 56-21, and directions for 
using the Elliott cup in Proceedings A. S. T. M., 1917, pt. x, p. 414. 


4 Circular of the Bureau of Standards 
4. BASIS OF PURCHASE. 


Drier shall be purchased by volume, the unit being a gallon of 
231 cubic inches at 15.5° C. (60° F.). The volume may be deter- . 
mined by measure or, in case of large deliveries, it may be easier to 
determine the net weight and specific gravity at 15.5/15.5° C. 
(60/60° F.) of the delivery. The weight per gallon in pounds can 
then be determined by multiplying the specific gravity by 8.33. 
The net weight in pounds divided by the weight per gallon gives 
the number of gallons. : ae 


OOOO 
ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 


AT 
5 CENTS PER COPY 
Vv. 


DEPARTMENT OF COMMERCE. 


BUREAU OF STANDARDS. 


S. W, STRATTON, Director. 


CIRCULAR OF THE BUREAU OF STANDARDS. 


No. lL1l. 


[2d edition, Issued June 2z, 1922.] 


UNITED STATES GOVERNMENT SPECIFICATION FOR 
FLAT INTERIOR LITHOPONE PAINT, WHITE 
AND LIGHT. TINTS. 


FEDERAL SPECIFICATIONS BOARD. 
STANDARD SPECIFICATION No. 21. 


This Specification was officially adopted by the Federal Specifications Board 
on February 3, 1922, for the use of the Departments and Independent Establish- 
ments of the Government in the purchase of materials covered by it. 


CONTENTS. 

Page 
RRP oo, vse icc bee srw h nn ty OTA T CORO, CFE ete se 
eee ale hy 2 2. 2G. geet Mes te See thy PARA Shas ey oN nae 2 
2. SEADOTALOrW EXAMINATION: | 6.6... Kis pe ee Gt aE Ee Oe ee Ee 7 3 
Re RE ME TELE Pogo oc a ih sep yi es Ves iniels <a oF § ZAP nth oceiors-» ha eens Sear HCR 5 
sak al dec c's Sa we FR wa ee a hb a aly nd OTE e hig Man pe ee 7 

1. GENERAL. 


This specification covers ready-mixed lithopone paints, fre- 
quently known as flat, washable wall paint, in white and a variety 
of light tints. Paints under this specification are not intended 
for outside exposure; they shall dry to dead flat opaque coats 
that will adhere well to wood, metal, and plaster, stand washing 
with soap and water, and show no material change in color on 
exposure to light. 

The paint shall be purchased by volume (231 cubic inches to 
the gallon). 


63900°—23 


2 Circular of the Bureau of Standards 


(a) PrcMENT.—The pigment shall consist of: 


Maximum. Minimum. 


Per cent. | Per cent. 
80 


Lithopore: 5505 sek eh ie DO Gaye ea ee Bh ac a cre eee oe rn 
SiN OTIMES,. 0. vccinccd'snd ones os 00s LER OE Rohh Oe BG Chee eRe eee eee 10. AI aie cee 
Tinting and extending pigments .o255000... 7g cen es teva e Lew len ood dent eee LO Fa uk ota 
Material soltible in water . 5.o.0.6.e ibis vwicesace bis ay aurm ais msl niece Bie we gia siesta etn i aan 0.8 


a 


ty) sate lithopone used must contain not less than 26 per cent of zinc sulphide and must not darken 

(b) Ligurip.—The liquid portion of the paint shall consist of 
treated drying oils or varnish, or a mixture thereof, and turpentine 
or volatile mineral spirits, or a mixture thereof, in such proportions 
as to insure not less than 25 per cent of nonvolatile vehicle. The 
nonvolatile vehicle shall dry to a tough and elastic film. 

(c) Patnt.—The paint shall be well ground, shall not settle 
badly, cake, or thicken in the container, shall be readily broken 
up with a paddle to a smooth, uniform paint of brushing con- 
sistency, and shall dry within 18 hours to a dead flat finish without 
streaking, running, or sagging and free from laps and brush 
marks. The color and hiding power when specified shall be equal 
to those of a sample mutually agreed upon by buyer and seller. 
After drying for not less than five days, marks made on the painted 
surface with a soft lead pencil (No. 2 Mogul) shall be easily removed 
by washing with soap and warm water without appreciably 
marring the paint surface. The weight per gallon shall be not 
less than 141% pounds. 

The paint shall consist of: 


cry 
ee ee ee ar 


ee ee ee ee i ee ie i ray 


er 
Coamwe particles and ‘“‘skins”’ (total residue retained on No. 325 screen based on 
pigment) 


a er ras 


Notr.—Deliveries will, in general, be sampled and tested by the following methods, 
but the purchaser reserves the right to use any additional available information to 
ascettain whether the material meets the specification. 


2. SAMPLING. 


It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1,000 packages shall be taken as 
representative of the whole. Whenever possible, an original 
unopened container shall be sent to the laboratory, and when this 
is for any reason not done the inspector shall determine by thor- 


i 


Specification for Flat Intervor Lithopone Paint 3 


ough testing with a paddle or spatula whether the material meets 
the requirement regarding caking in the container. He shall 
then thoroughly mix the contents of the container and draw a 
sample of not less than 5 pounds. This sample shall be placed ina 
clean, dry metal or glass container, which it must nearly fill. The 
container shall be closed with a tight cover, sealed, marked, and 
sent to the laboratory for test with the inspector’s report on caking. 

When requested, a duplicate sample may be taken from the 
same package and delivered to the seller, and the inspector may — 
take a third sample to hold for test in case of dispute. 


3. LABORATORY EXAMINATION. 


(a) CAKING IN CONTAINER.—When an original package is re- 
ceived in the laboratory it shall be weighed, opened, and stirred 
with a stiff spatula or paddle. The paint must be no more difficult 
to mix to a uniform consistency than a good grade of flat paint. 
The paint shall finally be thoroughly mixed, removed from the con- 
tainer, and the container wiped clean and weighed. This weight 
subtracted from the weight of the original package gives the net 
weight of the contents. A portion of the thoroughly mixed paint 
shall be placed in a clean container and portions for the remaining 
tests promptly weighed out. 

(b) CoLror.—Place some of the paint on a clean, clear glass plate. 
Place some of the standard agreed upon beside the sample on the 
plate, turn the glass over, and compare the colors. 

(c) WEIGHT PER GALLON.—Weigh a clean, dry, 100 cc gradu- 
ated flask. Fill to the mark with the thoroughly mixed paint and 
weigh again. The increase in weight expressed in grams, divided 
by 100, gives the specific gravity, which multiplied by 8.33 gives 
the weight in pounds per gallon. 

(d) BRUSHING PROPERTIES, TIME OF DRYING, AND RESISTANCE 
“TO WASHING.—Brush the well-mixed paint on a suitable panel, 
which may be ground glass, steel, or well-filled wood. Note 
whether the paint works satisfactorily under the brush. Place 
the panel in a vertical position in a well-ventilated room and let it 
' stand for 18 hours. The paint should be dry and free from streaks. 

Let the panel stand for five days, then make marks on it with a 
soft lead pencil (No. 2 Mogul) and wash these marks off with warm 
(75° C.) distilled water and white floating soap, using a sponge or 
soft rag. The marks must be removed by this treatment without 
appreciably marring the paint film. 

Flow a portion of the paint on a clean glass plate. Let dry in 
a nearly vertical position at room temperature (65° to 100° F‘). 
The film shall show no streaking or separation within a distance of 
4 inches from the top. 


4 Circular of the Bureau of Standards 


(ec) Fastness To Licut.—Apply a sufficient number of coats 
of the paint to a ground-glass plate to completely hide the surface, 
cover half of this painted surface with opaque black paper, and 
expose indoors in a well-lighted room for five days. Remove the 
black paper and examine the surface. The exposed portion should 
be no darker than the portion protected by the black paper. 

(f) WaTER.—Mix 100 g of the paint in a 300 ce flask with 75 
ce of toluol. Connect with a condenser and distil until about 
50 ce of distillate has been collected in a graduate. The tem- 
perature in the flask should be then about 105 to 110° C. The 
number of cubic centimeters of water collecting under the toluol 
in the receiver is the percentage of water in the paint. Material 
complying with the specification should yield less than 1.0 ce. 

(9) VOLATILE THINNER.—Weigh accurately from 3 to 5 g of 
the paint into a tared flat-bottomed dish about 8 cm in diameter, 
spreading the paint over the bottom. Heat at 105 to 110° C. for 
three hours, cool, and weigh. Calculate the loss in weight as 
percentage of water and volatile thinner, subtract from this the 
percentage of water (3 (f/)), and report the remainder as oe 
thinner. 

(h) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 ¢ 
of the paint into a weighed centrifuge tube. Add 20 to 30 cc of 
“extraction mixture” (see Reagents), mix thoroughly with a glass 
rod, wash the rod with more of the extraction mixture, and add 
sufficient of the reagent to make a total of 60 cc in the tube. 
Place the tube in the container of a centrifuge, surround with 
water, and counterbalance the container of the opposite arm 
with a similar tube or a tube with water. Whirl at a moderate 
speed until well settled. Decant the clear supernatant liquid. 
Repeat the extraction twice with 40 cc of extraction mixture and 
once with 40 cc of ether. After drawing off the ether, set the 
tube in a beaker of water at about 80° C. or on top of a warm 
oven for 10 minutes, then in an oven at 105 to 110° C. for two 
hours. Cool, weigh, and calculate the percentage of pigment.. 
Grind the pigment to a fine powder, pass through a No. 80 screen 
to remove any skins, and preserve in a stopper bottle. Pre- 
serve the extracted vehicle for 3 (J). 

(1) PERCENTAGE OF NONVOLATILE VEHICLE.—Add pisd a the 
percentages of water (3 (f)), of volatile thinner (3 (g)), and of pig- 
ment (3 (h)), and subtract the sum from 100. ‘The remainder is 
the percentage of nonvolatile vehicle, which should be not less 
than one-third as large as the percentage of volatile thinner. 


Specification jor Flat Interior Lithopone Parnt 5 


(7) NATURE OF NONVOLATILE VEHICLE.—Evaporate the ex- 
tracted vehicle and extraction mixture from 3 (h) to about 5 cc 
Thoroughly clean with benzol a piece of bright sheet iron, tin 
plate, or terneplate. Spread a portion of the concentrated ex- 
tracted vehicle on the sheet of metal, allow to dry for 30 minutes 
_ at room temperature in a vertical position, bake for three hours 
at 100 to 110° C. (212 to 221° F.), remove from the oven, and 
keep at room temperature for three days. Test the film with a 
knife blade at a place not less than 2.5 cm (1 inch) from the edge. 
The film should be tough and elastic; if it powders or if particles 
fly under the test, it will be considered brittle, which will be cause 
for rejection. ‘The film must also stand light, vigorous rubbing 
with the finger without powdering or disintegrating. : 

(k) COARSE PARTICLES AND SKINS.—Dry in an oven at 105 to 
110° C. a No. 325 screen, cool, and weigh accurately. Weigh an 
amount of paint containing 10 g of pigment (see 3 (h)), add 50 cc 
of kerosene, mix thoroughly, and wash with kerosene through the 
screen, breaking up all lumps, but not grinding. After washing 
with kerosene until all but the particles too coarse to pass the 
screen have been washed through, wash all kerosene from the 
screen with ether or petroleum ether, heat the screen for one hour 
at 105 to 110° C., cool, and weigh. 


4. ANALYSIS OF PIGMENT. 


Use the pigment extracted in 3 (h). 

(a) QUALITATIVE ANALYsIS.—Make qualitative analysis fol- 
lowing ordinary methods. 

(6) MATTER SOLUBLE IN WATER.—Transfer 2.5 g of the pig- 
ment to a graduated 250 cc flask, add 100 ce of water, boil for 
five minutes, cool, fill to mark with water, mix, and allow to 
settle. Pour the supernatant liquid through a dry filter paper 
and discard the first 20cc. ‘Then evaporate 100 cc of the clear 
filtrate to dryness in a weighed dish, heat for one hour at 105 to 
110° C., cool, and weigh. ‘The residue should not exceed 0.008 g. 

(c) BartuM SULPHATE AND SILICEOUS MATERIAL.—Transfer 
-I g of pigment to a porcelain casserole or dish, moisten with a 
few drops of alcohol, add 40 cc of hydrochloric acid (1.1, specific 
gravity), cover, and boil to expel hydrogen sulphide; remove the 
cover and evaporate to dryness on the steam bath, moisten with 
hydrochloric acid, dilute with water, filter through paper, and 
wash with dilute hydrochloric acid and then with hot water until 


6 Circular of the Bureau of Standards 


the washings are free from zinc and chlorine. Ignite and weigh 
the residue, which will be barium sulphate and siliceous material. 

Mix the ignited residue with about 10 times its weight of anhy- 
drous sodium carbonate (grind the mixture in an agate mortar if 
necessary), fuse the mixture in a covered platinum crucible, heat- 
ing about one hour. Let cool, place the crucible and cover in a 
250 cc beaker, add about 100 cc of water, and heat until the 
melt is disintegrated. Filter on paper (leaving the crucible and 
cover in the beaker) and wash the beaker and filter thoroughly 
with hot water to remove soluble sulphates. Place the beaker 
containing the crucible and cover under the funnel, pierce the 
filter with a glass rod, and wash the carbonate residue into the 
beaker by means of a jet of hot water. Wash the paper with 
hot dilute hydrochloric acid (1:1), and then with hot water. If 
the carbonate residue is not completely dissolved, add sufficient 
dilute hydrochloric acid to effect solution, and remove the crucible 
and cover, washing them with a jet of water. Heat the solution 
to boiling and add 10 to 15 cc of dilute sulphuric acid, and 
continue the boiling for ro or 15 minutes longer. Let the pre- 
cipitate settle, filter on a weighed Gooch crucible, wash with hot 
water, ignite, cool, and weigh as BaSO,. Subtract from the re- 
sult of the previous determination to obtain the siliceous material. 

(dq) Tota, Zinc CALCULATED Aas ZINC OxmpE.—With material 
containing no interfering elements (iron, for example) weigh ac- 
curately about 1 g of pigment, transfer to a 400 cc beaker, 
moisten with alcohol, add 30 cc of hydrochloric acid (1:2), 
boil for two to three minutes, add 200 cc of water and a small 
piece of litmus paper; add strong ammonia until slightly alka- 
line, render just acid with hydrochloric acid, then add 3 ec of 
strong hydrochloric acid, heat nearly to boiling, and titrate with 
standard ferrocyanide as in standardizing that solution (see 
Reagents). Calculate total zinc as zinc oxide. 

When iron or other interfering elements are present (see 4 (a) ), 
take the filtrate containing the zinc from 4 (c), add a slight excess 
of bromine water and 2 g ammonium chloride, heat to nearly 
boiling, add an excess of ammonia, heat for about two minutes, 
filter, dissolve the precipitate in hydrochloric acid, add 2 g of 
ammonium chloride, and reprecipitate with ammonia as above. 
Filter, wash the precipitate with hot 2 per cent ammonium-chloride 
solution, unite the two filtrates, and determine zinc as above. 


Specification for Flat Intervor Lithopone Paint 7 


(e) Zinc OxipE.—Weigh accurately 2.5 g of pigment, transfer 
to a 250 cc graduated flask, moisten with a few drops of alcohol, 
add about 200 ce of 1 to 3 per cent acetic acid, shake vigorously 
and let stand for 30 minutes, shaking once every five minutes. 
Fill to the mark with 1 to 3 per cent acetic acid, mix, filter through 
a dry paper, discard the first 25 cc and determine zine in 100 cc 
of the filtrate (corresponding to 1 g) asin 4 (d). Calculate the 
percentage of zinc oxide. 

({) CALCULATIONS.—Subtract the percentage of zinc oxide 
(4 (e) ) from the percentage of total zine as zinc oxide (4 (d) ) and 
multiply the remainder by 1.2 to convert to percentage of zinc 
sulphide. In case the percentage of barium sulphate (4 (c) ) is 
not more than 2.86 times as great as the percentage of zinc sul- 
phide, add the two together and call the sum the percentage of 
lithopone. If the percentage of barium sulphate is greater than 


_ this amount, take 2.86 times the percentage of zinc sulphide as 


the percentage of barium sulphate to be included in the percentage 
oi lithopone and include the remainder in the percentage of tinting 
and extending pigments. Subtract the sum of the percentage of 
zine oxide (4 (e) ), lithopone, and matter soluble in water (4 (0) ) 
from 100. Call the remainder percentage of tinting and extending 
pigments. ; 


5. REAGENTS. 


(a) EXTRACTION MIXTURE.— 

10 volumes ether (ethyl ether). 
6 volumes benzol. 
4 volumes methyl alcohol. 
1 volume acetone. 

(6) ONE To THREE PER CENT AceETIC Acip.—Dilute 20 cc 
glacial acetic acid to 1,000 cc with distilled water. 

(c) URANYL INDICATOR FOR Zinc ‘JITRATION.—A 5 per cent 
solution of uranyl nitrate in water or a 5 per cent solution of 
uranyl acetate in water made slightly acid with acetic acid. 

(d) STANDARD PoTasstuM FERROCYANIDE.—Dissolve 22 g of 
the pure salt in water and dilute to 1,000 cc. To standardize, 
transfer about 0.2 g (accurately weighed) of pure metallic zinc or 
freshly ignited pure zinc oxide to a 400 cc beaker. Dissolve in 
10 ce of hydrochloric acid and 20cc of water. Drop in a small 
piece of litmus paper, add ammonium hydroxide until slightly 
alkaline, then add hydrochloric acid until just acid, and then 3 cc. 


8 Circular of the Bureau of Standards 


of strong hydrochloric acid. Dilute to about 250 ce with hot 
water and heat nearly to boiling. Run in the ferrocyanide solu- 
tion slowly from a burette with constant stirring until a drop 
tested on a white porcelain plate with a drop of the uranyl indi- 
cator shows a brown tinge after standing one minute. A blank 
should be run with the same amounts of reagents and water as in 
the standardization. The amount of ferrocyanide solution re- 
quired for the blank should be subtracted from the amounts used 
in standardization and in titration of the sample. The standardi- 
zation must be made under the same conditions of temperature, 
volume, and acidity as obtain when the sample is titrated. 


| ce aS SRS SSN ST PE SE TNS CAREERS Treen Saeraaerestar Se | 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT 
5 CENTS PER COPY 


V 


hie ae) Wg Sek 


DEPARTMENT OF COMMERCE. 
BUREAU OF STANDARDS. 


S. W. STRATTON, Director. 


CIRCULAR OF THE BUREAU OF STANDARDS. 


No. 117. 


[2d edition. Issued July 3, 1922.] 


UNITED STATES GOVERNMENT SPECIFICATION FOR 


INTERIOR VARNISH. 
FEDERAL SPECIFICATIONS BOARD. 
- STANDARD SPECIFICATION No. 22. 


Thit Specification was officially adopted by the Federal Specifications Board on 
February 3, 1922, for the use of the Departments and Independent Establish- 
- ments of the Government in the purchase of materials covered by it. 


CONTENTS. 
: Page 
By) ae ee OT CE Ree ae TRE RANT MERGE ON I 
Se al I Nh cg cd acti niaaen ped Wa Rn din edie Woks aig ok Deke 2 
ees 2 elaiyad AIR Geablalis Iaiah hal Mi r giaae ceihingrll Naha Rae a a ee alee 2 
Peerensupenee. folie. Tie FG TO. i. CORLL PO AT a 6 
1. GENERAL. 


The varnish shall be suitable for general interior use, both 
rubbed and unrubbed finish, including floors. It must be ca- 
pable of easy application with a brush in the ordinary manner 
according to the rules of good standard practice, must flow out 
to a good level coat free from runs, sags, pits, or other defects, and 
dry with reasonable promptness to a hard, somewhat elastic glossy 
coating which can be rubbed in 48 hours or less. The manufac- 
turer is given wide latitude in the selection of raw materials and 
processes of manufacture, so that he may produce a varnish of 
the highest quality. The varnish must meet the following 
requirements: 

APPEARANCE.—Clear and transparent. 

63901°—23 


2 Circular of the Bureau of Standards 


CoLtor.—Not darker than a solution of 3 g of potassium dichro- 
mate in 100 cc of pure sulphuric acid, specific BrAyEy, 1.84. 

FLASH POINT (CLOSED-CcUP).—Not below 30° C. (85° F.). 

NONVOLATILE MatTER.—Not less than 45 per cent by weight. 

Set to Toucu.—In not more than 4 hours. 

Dry Harp.—In not more than 24 hours. 

Dry To Rus.—In not more than 48 hours. 

TOUGHNESS.—Film on metal must stand rapid bending over a 
rod 3 mm (% inch) in diameter. 

WorKING PROPERTIES.—Must have good brushing, flowing, 
covering, leveling, and rubbing properties; and must show no 
impairment of luster or other defect when used where natural or 
illuminating gases are burned or when subjected to air currents 
during the process of drying or application. . 


WATER RESISTANCE.—The dried film must ghee Sate 


of cold water for not less than 18 hours without whitening or 
showing other visible defect. | 


Note.—Deliveries will, in general, be sampled and tested, by the following methods, but the pur- 
chaser reserves the right to use any available information to ascertain whether the material meets ie 


specification. 
2. SAMPLING. 


It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1,000 packages shall be taken as 
representative of the whole. Whenever possible, an original un- 
opened container shall be sent to the laboratory, and when for 
any reason this is not done, the inspector shall thoroughly mix 
the contents of the container sampled, transfer not less than 1 
quart to a clean dry glass bottle or tin can which must be nearly 
filled with the sample, securely stoppered with a new clean cork 
or well-fitting cover, or cap, sealed, and distinctly hee sh eg 
inspector. 


The inspector should take a duplicate fou the container 
sampled to be held for check in case of dispute, esi bidet set 


quested, should take a sample for the seller. 


3. LABORAT ORY EXAMINATION. 


The tin panels used in the following tests ‘shall be cut raves 


bright tin plate weighing not more than 25 g nor less than’ 19 
g per square decimeter (0.51 to 0.39 pound per square foot). 
(Commercial No. 31 gage bright tin plate should weigh about 


0.44 pound per square foot. It is important that = tin Meg 2c 


used shall be within the limits set.) 


a 


Specification for Intertor Varnish 3 


(a) APPEARANCE.—Pour some of the thoroughly mixed sam- 
ple into a clear glass bottle or test tube and examine by trans- 
mitted light. The varnish must be clear and transparent. 

(6) CoLlor.—Prepare a standard color solution by dissolving 
3 g of pure powdered potassium dichromate in 100 cc of pure 
concentrated sulphuric acid of specific gravity 1.84. Gentle 
heat may be used if necessary to perfect the solution of the di1- 
chromate. The standard color solution and a sample of the 
varnish to be tested shall be placed in clear, thin-walled glass 


tubes of the same diameter. The color comparison shall be 


made by placing the tubes close together and looking through 
them by transmitted Ben The tubes used for this test should 
be 1.5 to 2.0 cm (5% to 1% inch) in diameter and shall be filled to 
a depth of at least 2.5 we (1 inch). (Since the potassium di- 
chromate-sulphuric acid must be freshly made for this color 
comparison, it is frequently more convenient to compare samples 
with a permanently sealed tube of varnish which has. previously 
been found to be slightly lighter in color than the standard solu- 
tion of 3 g dichromate in sulphuric acid. When samples are 


found to be darker than this standard tube of varnish, the di- 


chromate standard should be made up for final decision.) 

(c) FuasH Pornt.—Determine with either the Tag or Elliott 
closed-cup tester. The former is preferred.’ 

(d) NONVOLATILE MATTER.—Place a portion of the sample in a 


‘stoppered bottle or weighing pipette. Weigh container and sam- 
ple. Transfer about 1.5 g of the sample to a weighed flat-bot- 


tomed metal dish about 8 cm diameter (a friction-top can plug). 
Weigh container again and by difference calculate the exact weight 


of the portion of sample transferred to the weighed dish. Heat 


dish and contents in an oven maintained at 105 to 110° C. (221 to 
230° F.) for three hours. Cooland weigh. From the weight of the 


residue left in the dish and weight of the sample taken, calculate 


the percentage of nonvolatile residue. 

(e) Dryinc Time.—Pour the varnish on a clean glass or bright 
tin plate not less than 15 cm (6 inches) long and 10 cm (4 inches) 
wide. Place the plate in a nearly vertical position in a well- 


ventilated room but notin the direct rays of the sun. The tempera- 


ture of the room should be from 21 to 32°C. (7o to 90° F.).. The 


film is tested at points not less than 2.5 cm (1 inch) from the edges 
of the film by touching lightly with the finger. The varnish is 


1 Direotions for using the Tag tester may be found in A. S. T. M. Standards D died and difections Le 


using the Elliott cup in Proceedings A. S. T.M., 1917, pt. 1, D. 414. 


4 Circular of the Bureau of Standards 


considered to have set to touch when gentle pressure of the finger 
shows a tacky condition but none of the varnish adheres to the 
finger. The varnish is considered to have dried hard when the 
pressure that can be exerted between the thumb and finger does 
not move the film or leave a mark which remains noticeable after 
the spot is lightly polished. If rapid light rubbing breaks the 
surface, the sample is considered not to have satisfactorily dried 
hard. In case the test shows time of setting to touch or drying 
hard more than 4 and 24 hours, respectively, two additional tests 
shall be run on different days and if the varnish does not meet the 
above drying and hardening requirements on both of these addi- 
tional tests it shall be considered unsatisfactory. In cases where 
different laboratories fail to agree on the drying test, due to 
different atmospheric conditions, and umpire tests are necessary, 
such tests shall be made in a well-ventilated room maintained at 
a temperature of 70° F. and relative humidity of 65 Per cent 
saturation. 

({) ToucHnEss.—Thoroughly clean with benzaly’ a year’ of 
bright tin 7.5 by 13 cm (about 3 by 5 inches). Flow the varnish 
on one side of the tin plate and set in a vertical position in a well- 
ventilated room, not in the direct rays of the sun, ata steht an inte 
not below 21° C. (70° F.). 

After the varnish on the tin plate has dried for 48 hours ihe 
to a temperature between 21 and 24° C. (70 to 75° F.), and with 
the varnish film on the outside, bend rapidly over a rod 3 mm 
(% inch) in diameter. The film must show no evidence of crack- 
ing or flaking. 

(g) WATER RESISTANCE.—Prepare a panel as in ay sald let 
it dry in a well-ventilated room for 48 hours. Place the panel in 
a beaker containing about 2.5 inches of distilled water at room tem- 
perature (immersing the end of the panel which was uppermost 
during the drying period) and leave in water for 18 hours. The 
varnish shall show no whitening and no more than a very slight 
dulling when observed after removing the panel co feaes water 
and drying for 2 hours. y sud 

(h) FLowInGc AND RUBBING PROPERTIES.—I Ronehatihe alin 
with benzol a glass plate about 15 by 20cm (6 by 8inches). Flow 


.°» the varnish so as to cover entirely one side of the plate and stand 


in a nearly vertical position with the long edge horizontal for 8 
minutes. ‘Then draw lightly a 25 mm (1 inch) section of a hard- 
rubber comb (having 8 to 10 teeth to the centimeter) horizontally 
across the varnish surface, first 2 cm from the bottom and then 2em 


Specification for Intertor Varnish 5 


from the top of the plate. Let panel stand in the same position 
for 20 minutes longer, then lay flat. An exaggerated condition of 
a dusty room shall be created by rubbing some cotton batting 
between the hands immediately over the panel. Let panel dry 
for a\ total of 48 hours in a well-ventilated room. If the comb 
marks show at this time, the varnish shall be rejected. If no 
comb marks show, the surface shall then be rubbed with pumice 
flour, water, and a felt pad with long, even, firm strokes back and 
forth in one or another direction, but not in circles, until every 
portion of the panel has been rubbed. Most.of the pumice will 
then be removed from the pad and panel, and the varnish film 
given a ‘‘water rub’”’ with the pad. 

A satisfactory rubbing varnish in the above test will yield a 
smooth, dull film even at those places where the dust particles 
have been encrusted in the film, and shall show no spots where 
the pumice has been ground into and become attached to the film, 
nor show any other evidence of gumming. No sweating shall 
occur anywhere on the film in #8 hours after rubbing. 

_ (4) Gas Trest.—Apparatus.—The necessary apparatus consists 
of a glass bell jar approximately 20 cm (8 inches) in diameter and 
30 cm (12 inches) in height, inside dimensions, having a ground- 
glass rim; a ground-glass base plate of suitable size; a small, 
kerosene glowlamp without chimney, or a small alcohol lamp 
filled with kerosene, using a round wick not over 6 mm (1% inch) 
in diameter and adjusted to give a flame 2 cm (4/; inch) in height. 
A wire or a light wooden frame is fitted inside the jar and provided 
with a support for holding a disk of tin plate 15 cm (6 inches) in 
diameter in a horizontal position 5 cm (2 inches) above the wick 
of the lamp. The frame must also be provided with several other 
supports above this disk for holding in a horizontal position the 
various varnished panels under test. The test panels consist of 
semicircular pieces of bright tin plate approximately 15 cm (6 
inches) in diameter. | 

- The form and arrangement of the above apparatus is designed 
to provide an even distribution of the products of combustion 
over the test panels. 

Method.—First determine the normal time required for the 
varnish under examination to set to touch at room temperature. 
Divide this time by five to arrive at the different drying periods 
at which the varnish is to be tested in the gastester. Thus, if a 
varnish sets to touch in five hours, samples should be tested for 
resistance to gas at drying periods of one, two, three, and four 


6 Circular of the Bureau of Standards 


hours; it is needless to use the fifth or five-hour period for the 
above varnish, as a varnish which has set to touch is practically 
immune to injury from -gas fumes. Similarly a varnish which 
sets to touch in one hour should be tested for resistance to gas at 
drying periods of 12, 24, 36, and 48 minutes. 

Example.—A vases which sets to touch in five hours i is tested 
as follows: 

First, clean two of the semicircular, bright, tin-plate panels 
carefully with benzol. Flow the varnish on one-half of panel 
No. 1 at, say, 10 a. m., and allow to drain in a nearly vertical 
position at room temperature. At 11 a. m., flow the varnish on 
the other half of panel No. 1; allow to drain as before. At 12 m. 
varnish one-half of panel No. 2, and at 1 p. m. varnish the other 
half, as above. At 2p. m. place the two panels close together in 
a horizontal position on the upper supports of the frame. Light 
the lamp and set it under the circular tin. Place the bell jar in 
position, centering it as nearly as possible, properly seated on the 
ground-glass plate. If the chamber is tight and lamp properly 
adjusted, the flame will be extinguished in about four minutes. 
After the panels have been in the chamber for half an hour, 
remove the bell jar and examine the ee = for Bes 
effects. | 
\ The varnish on all four sections hold remain bright ait aaa 
without trace of Sgt ony he ‘crow’s ities) Wipe or’ other 
defects. FATE G EL? 

4. BASIS OF PURCHASE, 


Varnish shall be Pisa by volume, ‘the unit being a gallon 
éf 231 cubic inches at 15.5°C. (60°F). The volume may | be deter- 
mined by measure, or, in case of large deliveries, it may be easier 
to determine the net weight and specific gravity at 15.5 /15. 5°. 
(60/60° F.) of the delivery. ‘The weight per gallon in pounds can 
then be determined by multiplying the specific gravity by 8.33. 
The net weight in pounds divided Phi the ment per a gives 
the number of gallons. 


ADDITIONAL COPIES . 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS . . 
| GOVERNMENT PRINTING OFFICE, 
WABHINGTON, B.C. 
5 CENTS PER COPY 
® c Vv : 


: 7 ‘ sage a4 ove Ot eyricieresy 
WASHINGTON : GOVERNMENT PRINTING OFFICE : 1922 


5 aie: 
we 


U. S. Gov't 
Standard 
Specification, 


No. 66. 


DEPARTMENT OF COMMERCE. 
BUREAU OF STANDARDS. 
George K. Burgess, Director. 


CIRCULAR OF THE BUREAU OF STANDARDS, NO. 146. 


[Issued September 25, 1923.] 


UNITED STATES GOVERNMENT SPECIFICATION FOR 


WATER-RESISTING RED ENAMEL. 


FEDERAL SPECIFICATIONS BOARD. 
STANDARD SPECIFICATION NO. 66. 


This specification was officially adopted by the Federal Specifications Board 
on September |, 1923, for the use of the Departments and Independent Estab- 
lishments of the Government in the purchase of water-resisting red enamel. 


CONTENTS. : 
: Page 
Se eres vine ye ce uae maces fies aedess <s I 
Te a vat ens ees ces Ss Pee Ber ears oe ete er Seg ATER es 2 
Siiliaborstoryoexbmiination : (22256520. . . aloes - aes Leon. 3 ba - 20) - 2 
Bp Dania Gh DUPCIORE farses pre oh, s aes oon a0 owrie cn con babar bh esendes meh epentn 6 
1, GENERAL. 


The material desired under this specification is an extremely 
durable, highest quality red enamel, suitable primarily for outside 
use. It should be made by grinding pure high color strength 
toluidine red toner (metanitro-paratoluidine-azo-betanaphthol), 
free from any base or substratum, with the very best water- 
resisting long oil spar varnish. The color and hiding power 
when specified shall be equal to those of a sample mutually 
agreed upon by buyer and seller. It must meet the following 
requirements: | 

WEIGHT PER GALLON.—Not less than 734 pounds. 

PIGMENT.—Not less than 6 per cent by weight; pigment to be 
composed entirely of pure high color strength toluidine red 
toner, free from any other organic coloring matter, base, or 


substratum. 
61692°—23 


2 Circular of the Bureau of Standards. 


COARSE PARTICLES AND ‘“‘SKINS”’ (total residue retained on No. 
325 sieve).—Not more than 0.5 per cent. 

NONVOLATILE MATTER.—Not less than 60 per cent by weight. 

SET TO Toucn.—In not more than 18 hours. 

Dry Harp AND ToucH:—In not more than 48 hours. 

WorKING PROPERTIES.—Enamel must have good brushing, 
flowing, covering, and leveling properties and must not cake in 
the container. 

WATER RESISTANCE.—Dried film must withstand ae water for 

18 hours and boiling water for 15 minutes verte whitening, 
dulling, or change in color. 

TOUGHNESS:—Enamel must pass a 50 per cent Kauri reduction 
test'at 24° Oye Me. 

Deliveries will, in general, be sampled and tested by the following 
methods, but the purchaser reserves the right to use any additional 
available information to ascertain whether the material meets the 
specification. 

2. SAMPLING. 

It is ; mutually agreed by buyer. and seller that a. single ues 
out of each lot of not more than 1,000 packages be taken as repre- 
sentative of the whole. Whenever possible, an original unopened 
container shall be sent to the laboratory, and when for any rea- 
tents of the container sampled, transfer not less than 1 raatt 
to a clean, dry glass bottle or tin can, which must be nearly filled 
with the sample, securely stoppered with a new, clean cork or well- 
fitting cover or cap, sealed and distinctly labeled by the inspector. 
The inspector should take a duplicate from the container sampled 
to be held for check in case of dispute, and, when requested, 
should take a sample for the seller. HE RSS 


3, LABORATORY EXAMINATION. 


The tin panels used in the following tests shall all be cut: tiem 
bright tin plate weighing not more than 25 nor less than 19 g per 
square decimeter (0.51 to 0.39 pound per square foot) (Com- 
mercial No. 31 gauge bright tin plate should weigh ‘about ‘0.44 
pound per square foot. It is important that! the tin plate’ used 
shall be within the limits'set.) The panels shall be about 7.5 by 
13 cm (3 by 5 mches) and must be panei gi = 
benzol immediately before using. ) ! i T9001 

(a) CAKING IN CONTAINER AND WoRiING. PROPER TAG, “when 
an original package is received in the laboratory, it shall be 


Specification for Water-Resisting Red Enamel. 3 


weighed, opened, and stirred with a stiff spatula or paddle. ‘The 
enamel must be no more difficult to break up than a normal good 
grade of enamel paint. The enamel shall finally be thoroughly 
mixed, removed from the container, and the container wiped 
clean and weighed. This weight subtracted from the weight of 
the original package gives the net weight of the contents. Apply 
some of the thoroughly mixed enamel, both by brushing and 
flowing, to clean glass plates. It should work easily under the 
brush. Dry both plates in a nearly vertical position. They 
should both dry without streaking, separating, or showing brush 
marks. A portion of thoroughly mixed enamel shall be placed 
in a clean container and the portions for the remaining tests 
promptly weighed out. 

(b) CoLOR AND Hipinc PowEr.—Place some of the enamel on a 
clean, clear glass plate. Place some of the standard agreed upon 
beside the sample on the plate, turn the glass over, and compare 
the colors by transmitted and reflected light. 

(c) WEIGHT PER GALLON.—Weigh a clean, dry, 100 cc gradu- 
ated flask. Fill to the mark with the thoroughly mixed enamel and 
weigh again. The increase in weight expressed in grams, divided 
by 100, gives the specific gravity, which, multiplied by 8.33, 
gives the weight in pounds per gallon. 

(d) COARSE PARTICLES AND SKINS.—Dry in an oven at 105 to 
110° C. a No. 325 sieve, cool, and weigh accurately. Weigh 
accurately about 50 g of the enamel, add 100 cc of kerosene, mix 
thoroughly, and wash with kerosene through the sieve, breaking 
up all lumps, but not. grinding. After washing with kerosene 
until all but the particles too coarse to pass the sieve have been 
washed through wash all kerosene from the sieve with ether or 
- petroleum ether, heat the sieve for one hour at 105 to 110° C., 
cool, and weigh. 

(e) PIGMENT. — Qualitative examination.—Pour about 1 g of the 
thoroughly stirred enamel, previously strained through a No. 200 
sieve into a 50 cc beaker. Add about 4o ce of chloroform 
(U. S. P.) and warm on the steam bath, stirring with a glass rod. 
A clear orange-red solution should result in a few minutes. Take 
another portion of the enamel and spread it with a spatula on a 
smooth, white surface, such as a piece of milk glass. ‘Touch a few 
drops of alcoholic sodium hydroxide solution to the center of the 
film and rub well with a glass spatula. There should be no change 
in color.’ | 


1 The presence of para nitraniline red is indicated by a violet color. 


4 Circular of the Bureau of Standards. 


Quantitative determination.—Weigh 1 g (+ 10 mg) of the 
enamel and 6g (+ 10 mg) of pure zinc oxide, place on a large 
glass plate, add.2 cc of linseed oil and rub up with a flat-bottomed 
glass pestle or muller, grinding with a circular motion 50 times. 
Gather up with a sharp-edge spatula and grind out twice more 
in like manner, giving the pestle a uniform pressure. Next 
weigh to + 1 mg an amount of pure high color strength toluidine 
red toner equal to 6 per cent of the weight of enamel taken, 
add 4 drops of linseed oil and rub up with the glass pestle. 
Then add 6 g of pure zinc oxide and 2 cc of linseed oil and treat 
in exactly the same manner as described above. Transfer por- 
tions of each paste to a clean microscope slide quite close together, 
and then draw a palette knife across both samples, so as to make 
them meet in a line. Compare the tints as shown on both sides 
of the glass. The color of the sample tested shall be not less 
than that of the selected standard, and the tone shall be not 
materially different from it. 

({) NONVOLATILE MATTER.—Place a portion of the sample in a 
stoppered bottle or weighing pipette. Weigh container and sam- 
ple. Transfer about 1.5 g of the sample to a weighed flat-bot- 
tomed metal dish about 8 cm in diameter (a friction-top can plug). 
Weigh container again and by difference calculate the exact weight 
of the portion of sample transferred to the weighed dish. Heat 
dish and contents in an oven maintained at 105 to 110° C. (221 to 
230° F.) for three hours. Cool and weigh. From the weight of 
the residue left in the dish and weight of the sample taken calcu- 
late the percentage of nonvolatile residue. | 

(g) Dryinc TrmzE.—Pour the enamel on one of the tin panels 
described above. Place the panel in a nearly vertical position in 
a well-ventilated room, but not in the direct rays of the sun. The 
atmosphere of this room must be free from products of combus- 
tion or laboratory fumes. The temperature of the room should 
be from 21 to 32° C. (7o to 90° F.).* The film is tested at points 
not less than 2.5 em (1 inch) from the edges of the film by touch- 
ing lightly with the finger. ‘The enamel is considered to have set to 
touch when gentle pressure of the finger shows a tacky condition, 
but none of the enamel adheres to the finger. The enamel is con- 
sidered to have dried hard when the: pressure that can be exerted 
between the thumb and finger does not move the film or leave a 
mark which remains noticeable after the spot is lightly polished. 
If rapid, light rubbing breaks the surface, the sample is considered 
not to have satisfactorily dried hard. In case the test shows time 
of setting to touch or drying hard more than 18 and 48 hours, 


: ; 
; 
a 
| 
. 


Specification for Water-Resistung Red Enamel. 5 


respectively, two additional tests shall be run on different days, 
and if the enamel does not meet the above drying and hardening 
requirements on both of these additional tests it shall be con- 
sidered unsatisfactory. In cases where different laboratories fail 
to agree on the drying test, due to different atmospheric condi- 
tions, and umpire tests are necessary, such tests shall be made in 
a well-ventilated room maintained at a temperature of 70° F’. and 


- relative humidity of 65 per cent saturation. 


(h) WatER RESISTANCE.—Pour the enamel on two of.the tin 
panels described above and allow to dry under the conditions 
described in paragraph (g) for 48 hours. Place one of these panels 
in a beaker containing about 2.5 inches of distilled water at room 
temperature (immersing the end of the panel which was upper- 
most during the drying period) and leave in water for 18 hours. 
The enamel shall show no whitening and no more than very. slight 
dulling either when observed immediately after removing from the 
water or after drying for 2 hours. Place the other panel in a 
beaker containing about 2.5 inches of boiling distilled water (im- 
mersing the end of the panel which was uppermost during the 
drying period) and allow to remain in the boiling water for 15 
minutes. ‘The enamel shall show no whitening, no more than a 
very slight dulling, and no material change in color, either when 
observed immediately after removing from the water or after 
drying for 2 hours. | 

(4) ToucHNEss.—The toughness of the enamel is determined 
by the Kauri reduction test, as follows: By proportionately reduc- 
ing its toughness by the addition of a standard solution of ‘‘run- 
Kauri” gum in pure spirits of turpentine. 

(1) Preparation of the “run Kaurt.”’—Arrange a distillation 
flask, water-cooled condenser, and a tared receiver on a balance. 
Place in the flask about one-third of its volumetric capacity 
of clear, bright hard pieces of Kauri gum broken to pea size. 
Carefully melt and distil until 25 per cent, by weight, of the gum 
taken is collected in the tared receiver. (At the end of the distil- 
lation the thermometer in the distillation flask with the bulb at 
the level of the discharging point of the flask should register about 
316° C. (600° F.).) Pour the residue into a clean pan, and when 
cold break up into small pieces. 

(2) Preparation of standard ‘“ryn-Kaurt’’ solution.—Place a 
quantity of the small broken pieces of run-Kauri, together with 
twice its weight of freshly redistilled spirits of turpentine, using 


‘only that portion distilling over between 153 and 170° C. (308 


and 338° F.) in a carefully tared beaker. Dissolve by heating 


6 Circular of the Bureau of Standards. 


to a temperature of about 149° C. (300° F.) and bring back to: 
correct weight when cold by the addition of the amount of redis- 
tilled spirits of turpentine necessary to replace the loss by evapora- 
tion during the dissolving of the gum. 

(3) Reduction of the enamel.—Having carefully determined the 
nonvolatile content of the enamel according to the method under 
paragraph (f) of this specification, take 100 g of the enamel and 
add to it an amount of the standard run-Kauri solution equiva- 
lent to 50 per cent, by weight, of the nonvolatile matter in the 
enamel. Mix the enamel and the solution thoroughly. : 

(4) Application of the enamel.—Flow a coat of the enamel thus 
reduced on one of the tin panels described above and let stand 
in a nearly vertical position at room temperature for one hour. 
Next place the panel in a horizontal position in a properly venti- 
lated oven and bake for five hours at 95 to 100° C. Remove the 
panel from the oven and allow to cool at room esa stoic prefer- 
ably 24° C. (75° F.) for one hour. 

(5) Bending the Panel: —Place the panel with the enameled side 
uppermost over a 3-mm (3% inch) rod, held firmly by suitable 
supports, at a point equally distant from the ‘top and bottom 
edges of the panel and bend the panel double rapidly. The enamel 
must show no cracking whatsoever at the point of bending. For 
accurate results the bending of the panel should always be done 
at 24°C. (75° F.), for a lowering of the temperature will lower the 
percentage of reduction that the enamel will stand without cracking, 
while an increase in the temperature increases the seers 2 of 
reduction that the enamel will stand. | 


4. BASIS OF PURCHASE... 


Enamel shall be purchased by volume, the unit being a gallon 
of 231 cubic inches at. 15.5° C. (60° F.). The volume may be 
determined by measure or, in case of large deliveries, it may be 
easier to determine the net weight and specific gravity at 15.5/15.5° 
C. (60/60° F.) of the delivery. The weight per gallon in pounds 
can then be determined by multiplying the specific gravity by 8. 33. 
The net weight in pounds divided by the weight per gallon gives 
the number of gallons. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 


AT 
5s CENTS PER COPY 


PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS 
COPY FOR PROFIT.—PUB. RES. 57, APPROVED MAY IT, 1922 


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U. “Ss. Gov't 
Standard 

Specification, 
No. 67. 


DEPARTMENT OF COMMERCE. 


BUREAU OF STANDARDS. 


George K. Burgess, Director. 


CIRCULAR OF THE BUREAU OF STANDARDS NO. 147. 
(Issued September 19, 1923.) 


UNITED STATES GOVERNMENT SPECIFICATION FOR 
GLOSS INTERIOR LITHOPONE PAINT, WHITE AND 
LIGHT TINTS. 


FEDERAL SPECIFICATIONS BOARD. 
STANDARD SPECIFICATION NO. 67. 


This specification was officially adopted by the Federal Specifications Board 
on September |, 1923, for the use of the Departments and Independent Establish- 
ments of the Government in the purchase of gloss interior lithopone paint, white 
and light tints. 


| CONTENTS. 
Page. 
PRET BD ie PN gh gO 8 EE ols AG 8s Oe gle OOP Mr as be cle Cee Be ee est I 
aac inane rely emetiraie, Seainr ia Mire aaticic artes I ae My a ae ea 2 
EE Oe 2 0 Rn eR RR ar NET A NE NR 3 
INR feos acca Me wah so pale ate leorngieg als be oa ks eae es 6 
Cy otc) 2 QR ean ie nmmaor enon anny erin nc oor ir ka 8 

1. GENERAL. 


This specification covers ready-mixed lithopone paints, fre- 
quently known as gloss mill white, in white and a variety of light 
tints. Paints under this specification are not intended for out- 
side exposure. They shall dry to gloss opaque coats that will 
adhere well to wood, metal, and plaster, stand washing with soap 
and water, and show no material change in color on exposure to 
light or material yellowing when kept in the dark. 

The paint shall be purchased by volume (231 cubic inches to 
the gallon). 


61693°—23 x 


2 Circular of the Bureau of Standards. | 


(a) P1GMENT.—The pigment shall consist of : 


Maximum.| Minimum. 


Per cent. | Per ewe 


Tlthronane dae oa ce cca cnnsccuseceuneceascuseneveneces anes hau e ee smn 0 ah an ama a ee a 

TFT OEMS oo as tga Gh ne 6 Wh ded wow did.in lal bulla Awe Ys alg ptm ribs atk ln ie 20 
Tinting and extending pigments... ........6.c.c cee cece cece tees ect eeasee bese nine 2s fe Mee ere Ope es 
Material soluble in Water... cc ccc a ccwsws wincicndinnw cbegsdune cn ee ele she  teeuen 6: 6 ie oa Ponet eaek 


a a Ov enn een een mmceeete me BI 
1 The lithopone used must contain not less than 26 per cent of zine sulphide and must not darken on . 
exposure. 


In no case shall the sum of zinc oxide and lithopone be less 
than 95 per cent. 

(b) Liourw.—The liquid portion of the paint shall consist of 
treated drying oils or varnish, or a mixture thereof, and turpen- 
tine or volatile minera! spirits, or a mixture thereof, in such pro- 
portions as to insure not less than 60 per cent of nonvolatile 
vehicle. The nonvolatile vehicle-shall dry to a ge atl elastic 
film. el 

(c) Parnt.—The paint shall be-well ee ote oe "gets 
badly, cake, or thicken in the container, shall be readily broken 
up with a paddle to a smooth, uniform paint of brushing consist- 
ency, and shall dry within 24 hours to a varnish gloss finish with- 
out streaking, running, or sagging, and free from laps and brush 
marks. ‘The color and hiding power when specified shall be equal 
to those of a sample mutually agreed upon by buyer and seller, 
After drying for not less than five days marks made on the painted 
surface with a soft lead pencil-(No. 2 Mogul) shall be easily re- 
moved by washing with soap, and. warm water without appre- 
ciably marring the paint surface. The weight per gallon shall be 
not less than 124 pounds. The paint shall consist of: 


_- 
2 


Deliveries will, im esa: be pride: wee phe we ew the jollowing 
methods, but the purchaser reserves the right to use any additional 
available. information to ascertain whether. the. Cte He meets the 
specification. >» bre .totew Bi 

2. SAMPLING. ; 

It is mutually agreed by buyer and seller that a cine beds snd 
out of each lot of not more than 1,000 packages shall be taken, as 
representative of the whole. Whenever possible, an original 


Specification jor Gloss Intervor Lithopone Paint. 3 


unopened container shall be sent to the laboratory, and when this 
is for any reason not done the inspector shall determine by thorough 
testing with a paddle or spatula whether the material meets the 
requirement regarding caking in the container. He shall then 
thoroughly mix the contents of the container and draw a sample 
of not less than 5 pounds. This sample shall be placed in a clean, 
dry metal or glass container, which it must nearly fill. The con- 
tainer shall be closed with a tight cover, sealed, marked, and sent 
to the laboratory for test with the inspector’s report on caking. 

When requested, a duplicate sample may be taken from the 
same package and delivered to the seller, and the inspector may 
take a third sample to hold for test in case of dispute. 


3. LABORATORY EXAMINATION. 


© (a) Caxinc In CONTAINER.—When an original package is 
received in the laboratory, it shall be weighed, opened, and 
stirred with a stiff spatula or paddle. The paint must be no more 
difficult to mix to a uniform consistency than a good grade of 
gloss mill white. The paint shall finally be thoroughly mixed, 
removed from the container, and the container wiped clean and 
weighed. This weight subtracted from the weight of the original 
package gives the net weight of the contents. A portion of the 
thoroughly mixed paint shall be placed in a clean container and 
portions for the remaining tests promptly weighed out. 

(b) Coyor.—Place some of the paint on a clean, clear glass 
plate. Place some of the standard agreed upon beside the sample 
on the plate, turn the glass over, and compare the colors. 

(c) WEIGHT PER GALLON.—Weigh a clean, dry, 100 cc grad- 
uated flask. Fill to the mark with the thoroughly mixed paint 
and weigh again. The increase in weight expressed in grams, 
divided by 100, gives the specific gravity, which, multiplied by 

8.33, gives the weight in pounds per gallon. 

-. (d) BRUSHING PROPERTIES, TrmE OF DRYING, AND RESISTANCE 
to WasHING.—Brush the well-mixed paint on a suitable panel, 
“which may be ground glass, steel, or well-filled wood. Note 
whether the paint works satisfactorily under the brush. Place 
the panel in a vertical position in a well-ventilated room and let 
it stand for 24 hours. The paint should be dry and free from 
‘streaks. Let the panel stand for five days, then make marks on 
it with a soft lead pencil (No. 2 Mogul) and wash these marks off 
with warm (75° C.) distilled water and white floating soap, using 


4 Circular of the Bureau of Standards. 


a sponge or soft rag. The marks must be removed: by, this treat- 
ment without appreciably marring the paint film. } 

Flow a portion of the paint on a clean glass plate. Let dry ina 
nearly vertical position at room temperature (65 to 100° F.). The 
film shall show no streaking or separation within a distance of 
4 inches from the top. tte 

(ec) Fastness to Licnr.—Apply a sufficient number of. coats 
of the paint to a ground-glass plate to completely hide the, sur- 
face, cover half of this painted surface with opaque black paper, 
and expose indoors in a well-lighted room for five days., Remove 
the black paper and examine the surface. The exposed portion 
should be no darker than the portion protected by the black 
paper. 

(f) YELLowinc.—Apply a sufficient number of coats of the 
paint to two ground-glass plates to completely hide the surface; 
after applying the last coat let dry in a well-lighted room for 
five days. Place one of the plates in a dark room or cabinet * 
with a warm, very humid atmosphere, for 96 hours. Remove 
from cabinet and compare with the plate that has been kept in. 
a light room. The plate kept in the dark shall be only slightly 
yellower than the plate kept in the light. There shall be no 
greater difference in color of the two plates than there will be 
with similar plates coated with the best grade of paint of this 
general nature. 

(g) WatTER.—Mix 100 g of the paint in a 300 ce flask wits 75 
ce of toluol. Connect with a condenser and distil until about 50 
ce of distillate has been collected in a graduate The temperature 
in the flask should be then about 105 to 110° C. The number of 
cubic centimeters of water collecting under the toluol in she 
receiver is the percentage of water in the paint. 

(hk) VOLATILE THINNER.—Weigh accurately from 3 to 5 2 
of the paint into a tared flat-bottomed dish about 8 cm,in diam- 
eter, spreading the paint over the bottom. Heat at 105 to 110° 
C. for three hours, cool, and weigh. Calculate the loss in weight as 
percentage of water and volatile thinner, subtract from, this the 
percentage of water (3, 9); and report the remainder as volatile 
thinner. 

(1) PERCENTAGE OF PIGMENT.—Weigh acquit Smal I 5 g 
of the paint into a weighed centrifuge tube. Add .20 to 30 cc 
of ‘‘extraction mixture” (see Reagents), mix thoroughly with a 


1A convenient cabinet for this test is described in Circular No. 152, Hducational! Bureau, Scientific 
Section, Paint Manufacturers’ Association of the United States. 


Specification for Gloss Interior Lithopone Pant. 5 
glass rod, wash the rod with more of the extraction mixture, and 
add sufficient of the reagent to make a total of 60 cc in the tube. 
Place the tube in the container of a centrifuge, surround with 
water, and counterbalance the container of the opposite arm with 
a similar tube or a tube with water. Whirl at a moderate speed 
until well settled. Decant the clear supernatant liquid. Repeat 
the extraction twice with 40 cc of extraction mixture and once 
with 4o ce of ether. After drawing off the ether set the tube in a 
beaker of water at about 80° C. or on top of a warm oven for 10 
minutes, then in an oven at 105 to 110° C. for two hours. Cool, 
weigh, and calculate the percentage of pigment. Grind the pig- 
ment to a fine powder, pass through a No. 80 sieve to remove any 
skins, and preserve in a stoppered bottle. Preserve the extracted 
vehicle for 3 (k). 

(7) PERCENTAGE OF NONVOLATILE VEHICLE.—Add. together 
the percentages of water (3, g), of volatile thinner (3, 2), and of 
pigment (3, 7), and subtract the sum from roo. The remainder 
is the percentage of nonvolatile vehicle. 

(k) NaTuRE oF NONVOLATILE VEHICLE.—Evaporate the ex- 
tracted vehicle and extraction mixture from 3 (2) to about 5 cc. 
Thoroughly clean with benzol a piece of bright sheet iron, tin 
plate, or terneplate. Spread a portion of the concentrated 
extracted vehicle on the sheet of metal, allow to dry for 30 minutes 
at room temperature in a vertical position, bake for three hours 
at 100 to 110° C. (212 to 221° F.), remove from the oven, and keep 
at room temperature for three days. Place the panel with the 
coated side uppermost over a 3 mm (14-inch) rod, held firmly by 
suitable supports, at a point equally distant from the top and 
bottom edges of the panel and bend double rapidly. The dried 
vehicle must show no cracking whatever at the point of bending. 
Test the film with a knife blade at a place not less than 2.5 cm 
(t inch) from the edge. The film should be tough and elastic. 
If it powders, or if particles fly under the test, it will be considered 
brittle, which will be cause for rejection. The film must also 
stand light, vigorous rubbing with the finger without powdering 
or disintegrating. 

(1) COARSE PARTICLES AND SKINS.—Dry in an oven at 105 to 
110° C. a No. 325 sieve, cool, and weigh accurately: Weigh an 
‘amount of paint containing 10 g of pigment (see 3, 7), add 50 cc 
of kerosene, mix thoroughly, and wash with kerosene through 
the sieve, breaking up all lumps, but not grinding.. After washing 


6 Circular of the Bureau of Standards. 


with kerosene until all but the particles too coarse to pass the sieve 
have been washed through wash all kerosene from the sieve with 
ether or petroleum ether, heat the sieve for one hour at 105 to 
110° C., cool, and weigh. 


4. ANALYSIS OF PIGMENT. 


Use the pigment extracted in 3 (7). 

(a) QUALITATIVE ANALYsIS.—Make qualitative analysis, fol- 
lowing ordinary methods. 

(6) MATTER SOLUBLE IN WATER.—Transfer 2.5 g of the pig- 
ment to a graduated 250 cc flask, add 100 cc of water, boil for five 
minutes, cool, fill to mark with water, mix, and allow to settle. 
Pour the supernatant liquid through a dry filter paper and dis- 
card the first 20 cc. Then evaporate 100 cc of the clear filtrate 
to dryness in a weighed dish, heat for one hour at 105 to 110° C., © 
cool, and weigh. 1 | 

(c) BARIUM SULPHATE AND SILICEOUS MATERIAL.—Transfer 1 
g of pigment to a porcelain casserole or dish, moisten with a few 
drops of alcohol, add 40 cc of hydrochloric acid (1.1 specific 
gravity), cover, and boil to expel hydrogen sulphide. Remove the 
cover and evaporate to dryness on the steam bath, moisten with 
hydrochloric acid, dilute with water, filter through paper, and 
wash with dilute hydrochloric acid and then with hot water until 
the washings are free from zinc and chlorine. Ignite and weigh 
the residue, which will be barium sulphate and siliceous material. 

Mix the ignited residue with about 10 times its weight of anhy- 
drous sodium carbonate (grind the mixture in an agate mortar, if 
necessary), fuse the mixture in a covered platinum crucible, 
heating about one hour. Let cool, place the crucible and cover in 
a 250 cc beaker, add about 100 cc of water, and heat until the melt 
is disintegrated. Filter on paper (leaving the crucible and cover 
in the beaker) and wash the beaker and filter thoroughly with 
hot water to remove soluble sulphates. Place the beaker con- 
taining the crucible and cover under the funnel, pierce the filter 
with glass rod, and wash the carbonate residue into the beaker 
by means of a jet of hot water. Wash the paper with hot, dilute 
hydrochloric acid (1:1) and then with hot water. If the car- 
bonate residue is not completely dissolved, add sufficient dilute 
-hydrochloric acid to effect solution and remove the crucible and 
cover, washing them with a jet of water. Heat the solution to 
boiling and add 10 to 15 cc of dilute sulphuric acid and continue 
the boiling for 10 or 15 minutes longer. Let the precipitate 


a ee ae 


4 
: 
j 
3 
4 


Specification jor Gloss Interior Lithopone Patnt. 7 


settle, filter on a weighed Gooch crucible, wash with hot water, 
ignite, cool, and weigh as BaSO,. Subtract from the result of the 
previous determination to obtain the siliceous material. 

(d) Tora, ZINC CALCULATED AS ZINC OxIDE.—With material 
containing no interfering elements (iron, for example) weigh 
accurately about 1 g of pigment, transfer to a 400 cc beaker, 


‘moisten with alcohol, add 30 cc of hydrochloric acid (1:2), boil 


for two to three minutes, add 200 cc of water and a small piece of 
litmus paper; add strong ammonia until slightly alkaline, render 
just acid with hydrochloric acid, then add 3 cc of strong hydro- 
chloric acid, heat nearly to boiling, and titrate with standard 
ferrocyanide as in standardizing that solution (see Reagents). 
Calculate total zinc as zinc oxide. 

When iron or other interfering elements are present (see 4, a), 
take the filtrate containing the zinc from 4 (c), add a slight excess 
of bromine water and 2 g of ammonium chloride, heat to nearly 
boiling, add an excess of ammonia, heat for about two minutes, 
filter, dissolve the precipitate in hydrochloric acid, add 2 g of 
ammonium, chloride, and reprecipitate with ammonia as above. 
Filter, wash the precipitate with hot 2 per cent, ammonium- 
chloride solution, unite the two filtrates, and determine zinc as 


above... | 


— (e) Zinc OxipE.— Weigh accurately 2.5 g of pigment, transfer 
to.a 250 cc graduated flask, moisten with a few drops of alcohol, 
add about 200 cc of 1 to.3 per cent acetic acid, shake vigorously, 
and let stand for 30 minutes, shaking once very five minutes. Fill 
to the mark with 1 to 3 per cent acetic acid, mix, filter through a 
dry paper, discard the first 25 cc, and determine zinc in 100 cc of 
the filtrate (corresponding to 1 g) as in 4 (d).. Calculate the 
percentage of zinc oxide. : 

~ (f) CaLcuLations.—Subtract the percentage of zinc oxide (4, 
e) from the percentage of total zinc as zinc oxide (4, d) and multi- 
ply the remainder by 1.2 to convert to percentage of zinc sulphide. 
In case the percentage of barium sulphate (4, c) is not more than 
2.86 times as great as the percentage of zinc sulphide, add the two 
together and call the sum the percentage of lithopone. If the 
percentage of barium sulphate is greater than this amount, take 
2.86 times the percentage of zinc sulphide as the percentage of 
barium sulphate to ‘be included in the percentage of lithopone and 
include the remainder in the percentage of tinting and extending 
pigments. Subtract the sum of the percentages of zinc oxide 


8 Circular of the Bureau of Standards. 


(4, e), lithopone, and matter soluble in water (4, b)from 100. Call 
the remainder percentage of tinting and extending pigments. 


5. REAGENTS. 


(a) EXTRACTION MrxTuRE.— 

10 volumes ether (ethyl ether). 
6 volumes benzol. 
4 volumes methyl alcohol. 
I volume acetone. 

(b) ONE To THREE PER Cent Acetic Actp.—Dilute 20 ce os 
glacial acetic acid to 1,000 ce with distilled water. 

(c) UrRaNyL INDICATOR FOR ZINC TITRATION.—A 5 per cent 
solution of uranyl nitrate in water or a 5 per cent solution of 
uranyl acetate in water made slightly acid with acetic acid. 

(d) STANDARD PoTassIUM FERROCYANIDE.—Dissolve 22 g of the 
pure salt in water and dilute to 1,000 cc. To standardize, transfer 
about 0.2 g (accurately weighed) of pure metallic zinc or freshly 
ignited pure zinc oxide to a 400 ce beaker. Dissolve in ro cc of 
hydrochloric acid and 20ccofwater. Dropinasmall pieceoflitmus 
paper, add ammonium hydroxide until slightly alkaline, then add 
hydrochloric acid until just acid, and then 3 cc of strong hydro-. 
chloric acid. Dilute to about 250 ce with hot water and heat 
nearly to boiling. Run in the ferrocyanide solution slowly from a 
burette, with constant stirring until a drop tested on a white 
porcelain plate with a drop of the uranyl indicator shows a brown 
tinge after standing one minute. A blank should be run with the 
same amounts of reagents and water as in the standardization. 
The amount of ferrocyanide solution required for the blank should 
be subtracted from the amount used in standardization and in 
titration of the sample. The standardization must be made 
under the same conditions of temperature, volume, and acidity as 
obtain when the sample is titrated. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. ¢C. 
AT 
5 CENTS PER COPY 
PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS 
COPY FOR PROFIT.—PUB. RES. 57, APPROVED MAY II, 1922 


Vv 


mb ® DH H 


U.S. Gov’t 
Standard 
Specification, 


No. 115. 


DEPARTMENT OF COMMERCE. 
BUREAU OF STANDARDS. 


George EK. Burgess, Director. 


CIRCULAR OF THE BUREAU OF STANDARDS, No. 163. 
[February 20, 1924.] 


UNITED STATES GOVERNMENT SPECIFICATION FOR 
TITANIUM PIGMENT, DRY AND PASTE. . 


FEDERAL SPECIFICATIONS BOARD. 
STANDARD SPECIFICATION No. 115. 


This specificatio:. was officially adopted by the Federal Specifications Board 
on February 20, 1924, for the use of the Departments and Independent Estab- 
lishments of the Government in the purchase of titanium pigment, dry and paste. 


CONTENTS. 


Page. 

EE Bis ong widow vee h oh bo. © bhai oieie aie 60.504 nig psa oid as ale Wicla ts 1 

Re SG ey Bn oe ee a cd oo w Rs a Sa es hee vo pia Rie wale acme 2 

i iLanormioey examination, dry pigment. (0.6.0... eet ai Pe eid ders 3 

Pal EO BLATUINATION -Daste }. .<ivivis sie sisii> ik’ § eorvip Eat aaa de Ces veka ee 6 

RRB hind Sinie's othe 4 « Kk cand ait A #5 Sih nin.g'= AG ap ckoe hb tah ae ih oae moa nar 9 
1. GENERAL. 


Titanium pigment may be ordered in the form of dry pigment or 
paste ground in linseed oil. The material shall be purchased by 
net weight. | 

(a) Dry Picment.—The pigment shall be 25 per cent titantum 
oxide precipitated upon and coalesced with 75 per cent of blanc 
fixe (precipitated barium sulphate). It shall be thoroughly 


- washed, shall be free from adulterants, and shall meet the fol- 


lowing requirements. 

Color—Color strength—When specified, the color and color 
strength shall be equal to that of a sample mutually agreed upon . 
by buyer and seller. 


84628°—24 
e 


2 | Circular of the Bureau of Standards 


— 


Mini- | Mazi- 
mum. mum, 


Per cent. | Per cent. 
Coarse particles retained on No. 325 sieve... .25.ic: des bi dese ocncc cde cevesendegedell ce 1.0 
Titanium oxide ee ii bisigs 00002 Peeves rE es re 


(6) Paste.—The ‘paste shall be made by thoroughly grinding 
the above-described pigment with pure, raw, or refined linseed oil. 

The paste as received shall not be caked in the container and 
shall break up readily in oil to form a smooth paint of ead 
consistency. The paste shall consist of: 


Cem MEER Oe DCB HRM ERE Be HAE meer er eases ESewrssescusisanseuseace 


Care particles and “‘ skins ” (total residue retained on No. 325 sieve, based on pig- a. 
THONG)... 222 c ces ns cine vnuinisien sieis eu pie Saleen 5:c.b balan w o\ajalen bls ol line ia innit aes a . 


Deliveries will, in general, be sampled and tested by the following 
methods, but the purchaser reserves the right to use any additional 
available tnjormaiion to asceriain whether the. material meets the 
specification. 

2. SAMPLING. 

It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1,000 packages be taken as repre- 
sentative of the whole. 

(a) Dry Prcment.—The package is to be opened by the 
inspector and a sample of not less than 5 pounds taken at random 
from the contents and sent to the laboratory for test. 

(6) PastE.—Whenever possible, an original unopened con- 
tainer shall be sent to the laboratory; and when this is for any 
reason not done the inspector shall determine by thoroughly 
testing with a paddle or spatula whether the material meets the 
requirement regarding not caking in the container. (See 4 (a).) 
After assuring himself that the paste is not caked in the can, the 


inspector shall draw a sample of not less than 5 pounds of the ~ 


thoroughly mixed paste, place it in a clean, dry metal or glass 
container, which must be filled with the sample, closed with a 
tight cover, sealed, marked, and sent to the laboratory for test 
with the inspector’s report on caking in container. 


Specificaiion for Titamum Pigment 3 


When requested, a duplicate sample may be taken from the 
same package and delivered to the seller, and the inspector may 
take a third sample to hold for test in case of dispute. 


3. LABORATORY EXAMINATION, DRY PIGMENT. 


(a) CoLor.—Take 5 g of the sample, add 1.5 cc of linseed oil, 
rub up on a stone slab or glass plate with a flat-bottomed glass or 
stone pestle or muller to a uniform smooth paste. Treat in a simi- 
lar manner 5 ¢ of the standard titanium pigment. Spread the 
two pastes side by side on a clear, colorless glass plate and compare 
the colors. If the sample is as white as or whiter than the “ stand- 
ard,’’ it passes this test. If the ‘‘standard” is whiter than the 
sample, the material does not meet the specification. 

(6) CoLOR STRENGTH.—Weigh accurately o.o1 g of lamp- 
black, place on a large glass plate or stone slab, add 0.2 cc of lin- 
seed oil and rub up with a flat-bottomed glass pestle or muller, 
then add exactly 10 g of the sample and 2.5 cc of linseed oil, and 
grind with a circular motion of the muller 50 times; gather up 
with a sharp-edged spatula and grind out twice more in a like 
manner, giving the pestle a uniform pressure. Treat another 
0.01 g of lampblack in the same manner, except that 10 g of stand- 
ard titanium pigment is used instead of 10g of the sample. Spread 
the two pastes side by side on a glass microscope slide and com- 
pare the colors. If the sample is as light as or lighter in color 
than the “standard,” it passes this test. If the “standard” is 
lighter in color than the sample, the material does not meet the 
specification. 

(c) COARSE PartricLes.1—Dry in an oven at 105 to 110° C. a 
No. 325 sieve, cool, and weigh accurately. Weigh 10 g of the 
sample, wash with water through the sieve, breaking up all lumps 
either by gentle pressure with a pestle in a mortar, but not grind- 
ing, or with a brush on the sieve.. After washing with water until 
all but the particles too coarse to pass the sieve have been washed 
through, dry the sieve for one hour at 105 to 110° C., cool, and 
weigh. 

(d) QUALITATIVE ANALYSIS.—Place a small amount (about one- 
half gram) of the sample in a 250 cc Pyrex glass beaker; add 20 
ec of concentrated sulphuric acid and 7 to 8 g of ammonium sul- 
phate. Mix well, and boil fora few minutes. The sample should 


1 For a general discussion of sieve tests of pigments and data regarding many pigments on the market see 
Circular No. 148 of the Educational Bureau, scientific section, Paint Manufacturers’ Association of the 
United States. 


4 Circular of the Bureau of Standards. 


go completely into solution; a residue denotes the presence of 
Silica or siliceous matter. Cool the solution, dilute with 100 cc 
of water, heat to boiling, settle, filter, wash with hot 5 per cent 
sulphuric acid until free from titanium, and test the residue for 
lead, etc. Test the filtrate for calcium, zinc, iron, chromium, etc., 
by regular methods of qualitative analysis. For the iron deter- 
mination take a portion of the filtrate, add 5 g of tartaric acid, 
make slightly ammoniacal, pass in hydrogen sulphide in excess, 
and digest at the side of a steam bath for a while. No precipitate 
denotes absence of iron, nickel, cobalt, lead, copper, ete. A 
black precipitate easily soluble in dilute hydrochlo-ic acid denotes 
iron. For titanium test a small portion of the original filtrate 
with hydrogen peroxide (a clear yellow-orange color should result) 
and another portion with metallic tin or zinc (a pale blue to violet 
coloration should result). 

The pigment should show negative tests for sulphide sulphur, 
carbonates, and appreciable water-soluble matter. 

(ec) MorsturRE.—Place 1 g of the sample in a wide-mouth, short 
weighing tube provided with a glass stopper. Heat with the stop- 
per removed for two hours at a temperature between 105 and 110° 
C. Insert the stopper, cool, and weigh. Calculate the loss in 
weight as moisture. 

(f) MATTER SOLUBLE IN WATER.—Transfer 2.5 g of the pigment 
to a graduated 250 cc flask, add 100 cc of water, boil for five 
minutes, cool, fill to the mark with water, mix, and allow to 
settle. Pour the supernatant liquid through a dry filter paper 
and discard the first 20 cc. Then evaporate 100 cc of the clear 
filtrate to dryness in a weighed dish, heat for one hour at 105 to 110° 
~ ¢., cool, and weigh. 

ti) TITANIUM OXIDE. 
250 cc Pyrex beaker, add 20 cc of concentrated sulphuric acid 
and 7 to 8 g of ammonium sulphate. Mix well and heat on a hot 
plate until fumes of sulphuric acid are evolved, and then con- 
tinue the heating over a strong flame until solution is complete 
(usually not over five minutes of boiling) or it is apparent that the 
residue is composed of silica or siliceous matter. Caution should 
be observed in visually examining this hot solution. Cool the 
solution, dilute with 100 ce of water, stir, heat carefully to boiling 
while stirring, settle, filter through paper and transfer the precipi- 
tate completely to the paper. Wash the insoluble residue with 
cold 5 per cent (by volume) sulphuric acid until titanium is 
removed. 


Specification for Titanrwm Pigment. 5 


Dilute the filtrate to 200 cc and add about 10 ce of ammonia, 
specific gravity 0.90, to lower the acidity to approximately 5 
per cent sulphuric acid (by volume). 

Wash out a Jones reductor ? with dilute 5 per cent (by volume) 
sulphuric acid and water, leaving sufficient water in the reductor 
to fill to the upper level of the zinc. (These washings should 
require not more than one or two drops of 0.1 N potassium per- 
manganate solution to obtain the pink color.) Empty the 
receiver, and put in it 25 cc (measured in a graduate) of ferric 
sulphate solution. (See Reagents.) Reduce the prepared tita- 
nium solution as follows: (1) Run socc of the 5 per cent sulphuric 
acid solution through the reductor at a speed of about 100 cc 
per minute; (2) follow this with the titanium solution; (3) wash 
out with roo ce of 5 per cent sulphuric acid; (4) finally run through 
about 100 cc of water. 

Care should be observed that the reductor is always filled with 
solution or water to the upper level of the zinc. 

Gradually release the suction, wash thoroughly the glass tube 
that was immersed in the ferric sulphate solution, remove the’ 
receiver, and titrate immediately with o.1 N potassium ESHAaA 
ganate solution. (See Reagents.) 

1 cc 0.1 N KMnO,=0.00481 g Ti 
=0.00801 g TiO, 

Run a blank determination, using the same reagents, washing 
the reductor as in the above determination. Subtract this per- 
manganate reading from the original reading and calculate the 
final reading to titanium dioxide (TiO,) (which will include iron, 
chromium, arsenic, and any other substance which is reduced by 
zine and acid). (See 3 (2) for reporting TiO,.) ® 

(h) DETERMINATION OF BARIUM SULPHATE.—Ignite and weigh 
the precipitate of BaSO, obtained in separating the titanium.‘ 
(See 3 (g).) 

(4) IRON OxIpDE.—Prepare a standard ferric solution contain- 
ing o.oooo1 g Fe per cc. (See Reagents.) Weigh a1 g portion 
of the sample and treat as in 3 (g), transfer without filtering to a 
200 cc flask, cool, fill to the mark, and determine iron colorimetri- 
cally in 50 ce aliquots in the following manner. Filter through a 


3 Directions for preparing a Jones reductor may be found in Blair, *‘ The Chemical Analysis of Iron,” 
8th ed. Lippincott & Co., or Tread well-Hall, “Analytical Chemistry 2,”’ sth ed. J. Wiley & Sons, p. 638 
8 Any other accurate method of determining titanium oxide may be used. For a discussion of various 
methods see ‘‘The Analysis of Silicate and Carbonate Rocks,” by W. F. Hillebrand, U. S. Geological 
Survey Bulletin 7co. 
4 Jf the sample is impure it may be necessary to purify this precipitate, using appropriate methods. 
84628°—24 2 


6 Circular of the Bureau of Standards 


dry filter paper (discarding the first 20 cc), and transfer 50 ce 
of the filtrate to a clean 100 ce Nessler tube or other color com- 
parator. Add a drop or two of 0.1 N KMn0O, solution, to oxidize 
any ferrous iron until a faint pink color is obtained. Add 10 ce 
of ammonium or potassium thiocyanate solution (see Reagents), 
dilute to 100 cc, and mix thoroughly. Compare the color imme- 
diately with a series of standards, prepared side by side with the 
sample in similar tubes. 

Prepare the standards from the standard ferric solution so as 
to have a range of from 0.000005 g Fe to 0.00004 g (0.5 to 4.0 cc). 
Transfer the desired volumes of the standard dilute ferric solution 
to 100 ce Nessler tubes containing 50 ce each of an acid solution 
(made by dissolving 8 g of (NH,), SO, in water, adding 20 ce of 
concentrated H,SO,, cooling, diluting with water to 200 ce and 
mixing), add a drop of 0.1 N KMnO, solution (or sufficient to 
yield a pink color that will persist for 5 minutes), and then 10 cc 
of the thiocyanate solution. Finally dilute all standards with 
water to 100 ce and mix thoroughly. iy 


For a single sample it is more convenient to run the standard Fe solution from a 
burette into a Nessler tube containing 50 cc of the acid solution, a drop of 0.1 N KMnO, 
solution, and 10 cc of the thiocyanate solution, until on diluting to roo ce with dis- 
tilled water and mixing, the color exactly matches that of the sample. From the 
burette reading calculate the amount of Fe. The color comparisons must be made 
immediately after the standards are prepared. 


Calculate the total iron found to Fe,O, and report as such. 
Calculate the TiO, equivalent by multiplying by the factor 1.003 
and subtract this figure from the total titanium oxide as deter- 
mined in 3 (g) and report the remainder as ‘TiO,. 


4. LABORATORY EXAMINATION, PASTE. 


(a) CAKING IN CONTAINER.—When an original package is re- 
ceived in the laboratory it shall be weighed, opened, and stirred 
with a stiff spatula or paddle. The paste must be no more diffi- 
cult to break up and show no more caking than a normal good 
grade of titanium pigment paste. The paste shall finally be 
thoroughly mixed, removed from the container, the container 
wiped clean, and weighed. This weight subtracted from the 
weight of the original package gives the net weight of the con- 
tents. A portion of the thoroughly mixed paste shall be placed 
in a clean container, and the portions for the remaining tests. 
promptly weighed out. 

(6) MIXING WITH LINSEED O1L.—One hundred grams of the paste 
shall be placed in a cup, 40 ce of linseed oil added slowly with 


p- ee ee A ee eee be 


Specification for Tritaniwm Pigment. 7 


careful stirring and mixing with a spatula or paddle. The re- 
sulting mixture must be smooth and of good brushing consistency. 
Flow a portion of this paint on a clean glass plate. Let stand in 
a nearly vertical position at room temperature (65 to 100° F.). 
The film after four hours shall show no streaking or ean, 
within a distance of 4 inches from the top. 

(c) MoIstTURE AND OTHER VOLATILE MATTER.—Weigh tiaeiy 
from 3 to 5 g of the paste into a tared flat-bottomed dish, about 
8 cm in diameter, spreading the paste over the bottom. Heat at 
105 to 110° C. for three hours, cool, and weigh. Calculate the loss 
in weight as the percentage of moisture and other volatile matter. 

(d) PERCENTAGE OF PIGMENT.—Weigh accurately about 15 g 
of the paste into a weighed centrifuge tube. Add 20 to 30 cc 
of ‘extraction mixture’’ (see Reagents), mix thoroughly with a 
glass rod, wash the rod with more of the extraction mixture, and 
add sufficient of the reagent to make a total of 60 cc im the tube. 
Place the tube in the container of a centrifuge, surround with 
water, and counterbalance the container of the opposite arm with 
a similar tube or a tube with water. Whirl at a moderate speed 
until clear. Decant the clear supernatant liquid. Repeat the 
extraction twice with 40 cc portions of extraction mixture, and once 
with 40 cc of ether. After drawing off the ether, set the tube in a 
beaker of water at about 80° C. or on top of a warm oven for 10 
minutes, then in an oven at 105 to 110° C. for two hours. Cool, 
weigh, and calculate the percentage of pigment. 

(ec) EXAMINATION OF PIGMENT.—Grind the pigment from (d) 
to a fine powder, pass through a No. 80 sieve to remove any 
‘skins,’ and preserve in a stoppered tube and apply tests 3 (d), 
(f), (g), (A), and (2). If required, apply tests 3 (a) and (0) in 
comparison with a portion of pigment extracted from the standard 
paste in exactly the same manner as in extracting the sample. 

(f) PREPARATION oF Farry Acips.—To about 25 g of the paste 
in a porcelain casserole add 15 cc of aqueous sodium hydroxide 
(see Reagents), and 75 cc of ethyl alcohol, mix and heat uncovered 
on a steam bath until saponification is complete (about one hour). 
Add 100 cc of water, boil, add sulphuric acid of specific gravity 
1.2 (8 to 10 cc in excess), boil, stir, and transfer to a separatory 
funnel to which some water has been previously added. Draw 
off as much as possible of the acid aqueous layer, wash once with 
water, then add 50 ce of water and 50 cc of ether. Shake very 
gently with a whirling motion to dissolve the fatty acids in the 
ether, but not violently, so as to avoid forming an emulsion. 
Draw off the aqueous layer and wash the ether layer with one 15 


8 Circular of the Bureau of Standards. 


ce portion of water and then with 5 ce portions of water until free 
from sulphuric acid. ‘Then draw off completely the water layer. 
Transfer the ether solution to a dry flask, and add 25 to 50 g of 
anhydrous sodium sulphate. Stopper the flask and let stand with 
occasional skaking at a temperature below 25° C. until the water 
is completely removed from the ether solution, which will be 
shown by the solution becoming perfectly clear above the solid 
sodium sulphate. Decant this clear solution (if necessary through 
a dry filter paper) into a dry 100 cc Erlenmeyer flask. Pass a 
rapid current of dry air (pass through a CaCl, tower) into the 
mouth of the Erlenmeyer flask and heat to a temperature below 
75°C. ona dry hot plate until the ether is entirely driven off. 

It 1s wmportant to follow all of the details, since ether generally 
contains alcohol, and after washing with water always coniains 
water. It is very difficult to remove water and alcohol from fatty 
acids by evaporation, but the washing of the ether solution and sub- 
sequent drying with anhydrous sodium sulphate removes both water 
and alcohol. Ether, wm the absence of water and alcohol, 1s easily 
removed from fatty acids by gentle heat. 

The fatty acids prepared as above should be kept in a stoppered 
flask and examined at once. 

(g) TEST FOR MINERAL OIL, AND OTHER UNSAPONIFIABLE MAT- 
TER.—Place 1o drops of the fatty acid (f) ina 50 cc test tube, add 
5 ce of alcoholic soda (see Reagents), boil vigorously for five min- 
utes, add 4o cc of water, and mix; a clear solution indicates that 
~not more than traces of unsaponifiable matter are present. If 
the solution is not clear, the oil is not pure linseed oil. 

(h) lopINE NUMBER OF Farry Acrps.—Place a small quantity 
of the fatty acids (f) in a small weighing burette or beaker. 
Weigh accurately. Transfer (by dropping) about 0.15 ¢g (0.10 to 
0.20 g) to a 500 cc bottle having a well-ground glass stopper, or 
an Erlenmeyer flask having a specially flanged neck for the iodine 
test. Reweigh the burette or beaker and determine the amount 
of sample used. Add 10 ce of chloroform. Whirl the bottle to 
dissolve the sample. Add 10 cc of chloroform to two empty 
bottles like that used for the sample. Add to each bottle 25 cc of 
the Hanus solution (see Reagents) and let stand, with occasional 
shaking, for one-half hour. Add 10 cc of the 15 per cent potas- 
siusm-iodide solution and 100 cc of water, and titrate with standard 
sodium thiosulphate, using starch as indicator. The titrations on 
the two blank tests should agree within 0.1 cc. From the iodine 
value of the thiosulphate solution and the difference between the 


@ ae Se eee ee eee ee ae ee 


— a a oe oP re 


Specification for Titanium Pigment. 9 


average of the blank titrations and the titration on the sample, 
calculate the iodine number of the sample tested. (Iodine number 
is centigrams of iodine to 1 g of sample.) If the iodine number is 
less than 170, the oil does not meet the specification. 

(1) COARSE PARTICLES AND SKINS.—Dry in an oven at 105 to 
110° C. a No. 325 sieve. Weigh an amount of paste containing 
10 g of pigment (see 4 (d)), add 100 cc of kerosene, mix thoroughly, 
and wash with kerosene through the sieve, breaking up all lumps but 
not grinding. After washing with kerosene until all but particles 
too coarse to pass the sieve have been washed through, wash all 
kerosene from the sieve with ether or petroleum ether, heat the 
sieve for one hour at 105 to 110° C., cool, and weigh. 


5. REAGENTS. 


(a) ExTRACTION MIxTURE.— 
10 volumes ether (ethyl ether). 

6 volumes benzol. 

4 volumes methyl alcohol. 

I volume acetone. 
(b) Aguzous Sopium Hyproxipe.—Dissolve 100 g sodium 

hydroxide in distilled water and dilute to 300 cc. 

(c) STANDARD SODIUM THIOSULPHATE SOLUTION.—Dissolve pure 


sodium thiosulphate in distilled water that has been well boiled to 


free it from carbon dioxide, in the proportion of 24.83 g of crys- 
tallized sodium thiosulphate to 1,000 ce of the solution. It is. 
best to let this solution stand for about two weeks before standard- 
izing. Standardize with pure resublimed iodine.’ This solution 
will be approximately decinormal, and it is best to leave it as it is 
after determining its exact iodine value rather than to attempt to 
adjust it to exactly decinormal. Preserve in a stock bottle pro- 
vided with a guard tube filled with soda lime. 

(d) StarcH SOLUTION.—Stir up 2 to 3 g of potato starch or 5 
g of soluble starch with 100 cc of 1 per cent salicylic acid solution, 
add 300 to 400 cc of boiling water, and boil the mixture until the 
starch is practically dissolved, then dilute to 1 liter. 

(ec) Porassrum IopipE SoLuTION.—Dissolve 150 g of potassium 
iodide free from iodate in distilled water, and dilute to 1,000 cc. 

({f) Hanus SOLUTION.—Dissolve 13.2 g of iodine in 1,000 cc 
of 99.5 per cent glacial acetic acid which will not reduce chromic 
acid. Add enough bromine to double the halogen content, 
determined by titration (3 cc of bromine is about the proper 


’ Tread well-Hall, Analytical Chemistry, 2, sth ed., p. 645. 


fe) Circular of the Bureau of Standards. 


amount). The iodine may be dissolved by the aid of heat, but 
the solution should be cold when the bromine is added. 

(g) ALCOHOLIC SopruM HyprROxIDE SOLUTION:—Dissolve pure 
sodium hydroxide in 95 per cent ethyl alcohol in the proportion of 
about 22 g per 1,000 cc. Let stand in a stoppered bottle. De- 
cant the clear liquid into another bottle and keep well stoppered. 
This solution should be colorless or only slightly yellow when 
used, and it will keep colorless longer if the alcohol is previously 
treated with sodium hydroxide (about 80 g to 1,000 ec), kept at 
about 50° C. for 15 days and then distilled. 

(h) o.1 N Porasstum PERMANGANATE SOLUTION. Dissolve 
3.161 g of pure potassium permanganate in a liter of distilled 
water, let stand 8 to 14 days, siphon off the clear solution (or 
filter through an asbestos filter), and standardize as follows: In 
a 400 cc beaker dissolve 0.25 to 0.30 g of Bureau of Standards’ 
sodium oxalate in 250 cc of hot water (80 to go° C.) and add 15 
ce of dilute sulphuric acid (1:1). ‘Tiitrate at once with the potas- 
sium permanganate solution, stirring the lqgmd vigorously and 
continuously. The permanganate must not be added more 
rapidly than ro to 15 cc per minute, and the last 0.5 to 1 ce must 
be added dropwise with particular care to allow each drop to be 
fully decolorized before the next is introduced. ‘The solution 
should not be below 60° C. by the time the end point is reached. . 
(More rapid cooling may be prevented by allowing the beaker to 
stand on a small asbestos-covered hot plate during the titration. 
The use of a small thermometer as a stirring rod is most convenient.) 
The weight of sodium oxalate used multiplied by 0.8334 gives its 
iron equivalent, or multiplied by 1.1954 gives its titanium dioxide 
(TiO,) equivalent*. The permanganate solution should be kept 
in a glass-stoppered bottle painted black to keep out light. 

(t) FERRIC SULPHATE SOLUTION For TrtTanruM.—A solution 
containing 2 per cent of iron as ferric sulphate is desired and may 
be prepared as follows: , Dissolve 20 g of pure iron or plain carbon 
steel in a slight excess of hydrochloric acid, oxidize with nitric 
acid, heat with about 80 cc of sulphuric acid until fumes are 
evolved, finally cool, and dilute to 1,000 cc, set on steam bath, 
unti] dissolved, and filter if necessary. Add o.1 N permanga- 
nate solution until a faint pink color shows that any ferrous iron ~ 
has been oxidized. Ferric ammonium sulphate may also be used’. 


*International Atomic Weights, 1921-22. 
7Gooch, Methods in Chemical Analysis, rst ed., p. 426. 


Specification for Titanium Pigment. 1I 


(7) STANDARD FERRIC SULPHATE SOLUTION FOR COLORIMET- 
RIC DETERMINATION OF IRON.—Determine the strength of the 
ferric solution reagent used in 5 (2) in terms of iron and dilute 
this solution until one is obtained of the strength 1 cc=0.00001 
g Fe, 


(k) Porasstum THIOCYANATE INDICATOR.—Prepare a 2 per 
cent solution of the pure salt in distilled water. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT 


5 CENTS PER COPY 
Vv 


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* pacha D: carpe WN eet ne <a 


7 
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U. S. Gov't 
Master 
Specification, 


No. 137a 


DEPARTMENT OF COMMERCE 
BUREAU OF STANDARDS 


George K. Burgess, Director 


CIRCULAR OF THE BUREAU OF STANDARDS, No. 165 


[2d ed. Issued April 29, 1927] 


UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
PAINT, OLIVE DRAB (SEMIPASTE AND READY-MIXED) 


FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 137a 
[Revised September 2, 1925] 


This specification was officially adopted by the Federal Specifications Board 
on May 1, 1924, for the use of the departments and independent establish- 
ments of the Government in the purchase of olive drab paint (semipaste and 
ready mixed). 

[The date on which the technical requirements of this revision of this specification became mandatory 
for all departments and independent establishments of the Government was September 2, 1925. The changes 


included in this revision were authorized by the Federal Specifications Board and promulgated in a circular 
letter on above revision date.] 


CONTENTS 
Page 
I. General specifications__._.______________ See er ec ee ok, wee 2 
erence SSS SBS hattte Shek Wy Dees a? eet) ee 2 
Pena wminl firth Oe £oL Ce _ De pAe GIG. sel Devse to 5! 2 
.Vuaseneral requirements wo... wk ee eek dei ote os 2 
SRE ES a ae ae SOC 2 mee Cale pee,” TALE 2 
BS) IT eld gag AiR eiaeala gl ass Yes Ste Waki” Silo, Ge a pill naling 2 
PI Sk. Wh Ue ae ee on Sle Oe BED oe ee ee 3 
me wrcmmipastens OF ils NV IS LORE! AU See ee ae ee 3 
4 iiReddy-mined paintoclue) 22001 5. CAO. BA AO 3 
VI. Methods for sampling and testing._._.__.-__-..__-----_..- Lu Le 4 
1 RE SALES Te ge il Mth ARGUS eae Saaeies ree Remo ce TORS eer YH ee 4 
2. Laboratory examination, semipaste _.___..._-..._----___- 4 
eRe Ce IS Cl CT eras srerasie aig nat ns Ermer lanes vi 
4. Laboratory examination, ready-mixed paint_-..________.___ 9 
Si Menpenteces re 9G. 2 Sele SL aa 10 
VII. Packing and marking of shipments.__.-...-....------.---.---.-< 12 


Ee OE Oe a RE OTE ae ee reed aa eG Ok RE eA CG Riis bm Gees Pe 
43231°—27 : 


2 CIRCULAR OF THE BUREAU OF STANDARDS 
I. GENERAL SPECIFICATIONS 
There are no general specifications applicable to this specification : 
II, CLASSES 


Olive drab paint shall be of the following classes: Semipaste in 
linseed oil and ready mixed. 


III. MATERIAL 
See detail requirements. 
IV. GENERAL REQUIREMENTS 
See detail requirements. 


V. DETAIL REQUIREMENTS 
1, PIGMENT 


The pigment shall be composed of: 


Ingredients Maximum | Minimum 
Per cent Per cent 
White lead (basic carbonate, basic sulphate, or a mixture thereof) ........-.....-|.---------.. 35 
Zine'oxide (ZnO) ow ca coco dcado node scene ck wanes uebeeo en ee eee eee ee Rap 30 
White mineral pigments (containing no lead or zinc compounds), pure tinting 
eolors,,or.any: mixture thereof sc 22. bs eal ss 2 ails Jose seue2 ee 80 76 Bias. 
Organic CONOES gcc he cs ee a None@isleseadsetenwd- 


Balphide shlphur. pw snnenpeeeenpergecwsn= pena wanenechna eee None, wo-neeense=- 


In no case shall the sum of the basic lead carbonate, basic lead 
sulphate, and zinc oxide be less tham 70 per cent. The lead and 
zinc pigments may be introduced in the form .of any mixture pre- 
ferred of basic carbonate white lead, basic sulphate white lead, zinc 
oxide, or leaded zinc, provided the above requeet ees as to ee 
sition are met. 

The difference between the total lead weighed as taal iSitiphate 
ind the lead sulphate equivalent to the chromium found, multiplied 
by the factor 0.883, shall be considered white lead. It is not possible 
to determine the amount of lead carbonate and lead sulphate when 
carbonates or sulphates of other metals, such as calcium, ‘are present. 
Also neither basic lead carbonate nor basic lead sulphate is a definite 
compound. The factor to convert PbSO, to (PbCO;). Pb(OH), is 
0.854, to convert PbSO, to PbSO,PbO is 0.868, and to convert PbSO, 
to (PbSO,), PbO is 0.913. The arbitrary factor used under this 
specification is the mean of the largest and smallest of these three 
factors. 


—_ ees ee a or? | ei 


a ee. eee ee ee ee ee 


SPECIFICATION FOR OLIVE DRAB PAINT 3 
2. LIQUID 


The liquid in semipaste paint shall be entirely linseed oil; in ready- 
mixed paint it shall contain not less than 85 per cent linseed oil, the 
remainder to be combined drier and thinner. ‘The thinner shall be 
turpentine, volatile mineral spirits, or a mixture thereof. 


3. SEMIPASTE 


Semipaste shall be made by thoroughly grinding the pigment 
with linseed oil. 

The semipaste as received, and three months thereafter, shall be 
not caked in the container and shall break up readily in linseed oil to 
form a smooth paint of brushing consistency. It shall mix readily 
with linseed oil, turpentine, or volatile mineral spirits, or any com- 
bination of these substances, in all proportions without curdling. 
The color and hiding power when specified shall be equal to those of 
a sample mutually agreed upon by buyér and seller. The weight 
per gallon shall be not less than 18 pounds. The paste shall con- 
sist of: 


Ingredients Maximum } Minimum 


: Per cent Per cent 
PRE Se ME Te Re NGS a, eae ite RE eR ee a Se Rm MRI aE Pe EY ee a oe iy feeeal 


LOO S SEG, CH kl ae 5! ep Se 0 i ll let ak A Sd ie SR ee oe Red EL, oa 27 23 

MIGISLUPE.and ener volatile amaitet 202042225 oa FS lees eb So ieee oa 

Coarse particles and ‘‘skins’’ (total residue retained on No. 325 sieve based on 
ee ce haiichn ena teamed eh auy 2 OWN es eee 


4, READY-MIXED PAINT 


’ Ready-mixed paints shall be well ground, shall not settle badly or 
cake in the container, shall be readily broken up with a paddle to a 
smooth uniform paint of good brushing consistency, and shall dry 
within 18 hours to a full oil gloss without streaking, running, or 
sagging. The color and hiding power when specified shall be equal 
to those of a sample mutually agreed upon by buyer and seller. The 
weight per gallon spine be not less than 15 pounds. The paint shall 
consist of: 


Ingredients Maximum |} Minimum 


Per cent Per cent 
66 62 


Oe ow ww ww we we ow Oe SEES EE SSE SEERA SAT SOOO EME 


nn a ww a nn en eer se rn tren anne enna aeseere 


Catiee particles and ‘‘skins” (total residue retained on No. 325 sieve based on | 
i octign ot nr anccnbnnnasnwigamsderneasyannginnchas=<g amen wane cian eee bh Wa ges apicye ey a 


4 CIRCULAR OF THE BUREAU OF STANDARDS 
VI. METHODS FOR SAMPLING AND TESTING / 


Deliveries will, in general, be sampled and tested by the following 
methods, but the purchaser reserves the right to use any additional 
available information to ascertain whether the material meets the 
specification. : 

1, SAMPLING 


It is mutually agreed by buyer and seller that a single package out 
of each lot of not more than 1,000 packages shall be taken as repre- 
sentative of the whole. Whenever possible an original unopened 
container shall be sent to the laboratory, and when this is for any 
reason not done, the inspector shall determine by thorough testing 
with a paddle or spatula whether the material meets the requirement 
regarding caking in the container. He shall then thoroughly mix 
the contents of the container and draw a sample of not less than 5 
pounds of the thoroughly mixed paint, place it in a clean, dry metal 
or glass container, which must be filled with the sample, closed with 
a tight cover, sealed, marked, and sent to the laboratory for test with 
the inspector’s report on caking in container. 

When requested, a duplicate sample may be taken from the same 
package and delivered to the seller, and the inspector may take a 
third sample to hold for test in case of dispute. 


2. LABORATORY EXAMINATION, SEMIPASTE 


(a) Caxine In ConTaIneR.— When an original package is received 
in the laboratory it shall be weighed, opened, and stirred with a stiff 
spatula or paddle. The paste must be no more difficult to break up 
than a normal good grade of semipaste paint. The semipaste shall 
finally be thoroughly mixed, removed from the container, and the 
container wiped clean and weighed. This weight subtracted from 
the weight of the original package gives the net weight of the con- 
tents. A portion of thoroughly mixed semipaste shall be placed in 
a clean container and the portions for the remaining tests promptly 
weighed out. 

(6) Weicut pER GaLLon.—From the weight of a known volume 
of the paste calculate the specific gravity, which multiplied by 8.33 
gives the weight in pounds per gallon. Any suitable container of 
known volume may be used for the purpose, but a short cylinder of 
heavy glass with rounded bottom about 75 mm high and having 
a capacity of from 125 to 175 cc (a glass cap to keep dust from re- 
agent bottle stopper) is a convenient vessel for the purpose. The 
capacity of this vessel is determined to within 1 cc. The paste is 
packed into it until completely full, the top leveled off smooth with a 
spatula, and weighed to plus or minus 0.5 g. Subtract the weight of 
the empty container and divide the remainder by the number of 


: 
% 
| 
ay 
| 
4 
4 
’ 
| 
: 
] 
4 


SPECIFICATION FOR OLIVE DRAB PAINT 5 


cubic centimeters representing the capacity of the container. The 
quotient is the specific gravity, which can be thus determined within 
plus or minus 2 in the second decimal place. | 

(c) Mrxine with LinsrEep O1i.—One hundred grams of the paste 
shall be placed in a cup, 18 cc of linseed oil added slowly with care- 
ful stirring and mixing with a spatula or paddle. The resulting mix- 
ture must be smooth and of good brushing consistency. 3 

(d) Couor.—To the mixture made, in (c), add 3 cc of drier 
(F. S. B. No. 20) and mix thoroughly. Prepare a mixture of the 
standard paste with 18 cc of linseed oil and 3 cc of drier, using the 
same linseed oil and drier for both lots of paint. Apply both paints 
on clean metal or glass so that the edges touch one another. Let 
dry and compare the colors. 

(ec) Moisturn aNp Oruer Votatite Matter.—Weigh accurately 
from 3 to 5 g of the paste in a tared flat-bottomed dish about 8 
em in diameter, spreading the paste over the bottom. Heat at 105 
to 110° C. for three hours, cool, and weigh. Calculate the loss in 
weight as the percentage of moisture and volatile matter. 

(f) Percentace or Pigmunr.—Weigh accurately about 15 g of 
the paste in a weighed centrifuge tube. Add 20 to 30 cc of “ex- 
traction mixture’? (see Reagents), mix thoroughly with a glass rod, 
wash the rod with more of the extraction mixture, and add enough 
of the reagent to make a total of 60 cc in the tube. Place the tube © 
in the container of a centrifuge, surround with water, and counter- 
balance the container of the opposite arm with a similar tube or 
a tube with water. Whirl at a moderate speed until well settled. 
Decant the clear supernatant liquid, repeat the extraction three times 
with 40 cc of extraction mixture. After drawing off the extraction 
mixture, set the tube in a beaker of water at about 80° C. or on 
top of a warm oven for 10 minutes, then in an oven at 105 to 110° 
C. for two hours. Cool, weigh, and calculate the percentage of 
pigment. Grind the pigment to a fine powder, pass through a 
No. 80 sieve to remove any skins, and preserve in a stoppered bottle. 

(g) Preparation or Farry Acips.—To about 25 g of the paste in 
a porcelain casserole, add 15 cc of aqueous sodium hydroxide (see 
Reagents) and 75 cc of ethyl alcohol, mix and heat uncovered on a 
steam bath until saponification is complete (about one hour), Add 
100 ec of water, boil, add sulphuric acid of specific gravity 1.2 (8 to 
10 cc in excess), boil, stir, and transfer to a separatory funnel to 
which some water has been previously added. Draw off as much as 
possible of the acid aqueous layer and lead sulphate precipitate, wash 
once with water, then add‘50 cc of water and 50 cc of ether. Shake 
very gently with a whirling action to dissolve the fatty acids in 
the ether, but not so violently as to form an emulsion. Draw 
off the aqueous layer and wash the ether layer with one 15 cc por- 


6 CIRCULAR OF THE BUREAU OF STANDARDS 


tion of water and then with 5 cc portions of water until free from 
sulphuric acid. Then draw off the water layer completely. Transfer 
the ether solution to a dry flask and add 25 to 50 g of anhydrous 
sodium sulphate. Stopper the flask and let stand with occasional 
shaking at a temperature below 25° C. until the water is completely 
removed from the ether solution, which will be shown by the solu- 
tion becoming perfectly clear above the solid sodium sulphate. De- 
cant this clear solution, if necessary, through a dry filter paper into 
a dry 100 cc Erlenmeyer flask. Pass a rapid current of dry air 
(pass through a CaCl, tower) into the mouth of the Erlenmeyer 
flask and heat to a temperature below 75° C. on a dry, hot plate 
until the ether is entirely driven off. 

It is important to follow all of the details, since ether yerioncly con- 
tains alcohol, and after washing with water always contains water. 
It is very difficult to remove water and alcohol by evaporation from fatty 
acids, but the washing of the ether solution and subsequent drying with 
anhydrous sodium sulphate removes both water and alcohol. Ether, in 
the absence of water and alcohol, is easily removed from fatty acids by 
gentle heat. 

The fatty acids prepared as above should be kept in a stoppered 
flask and examined at once. 

(hk) Test ror Minera Orn aND OTHER UNSAPONIFIABLE Mart- 
TER.—Place 10 drops of the fatty acid (g) in a 50 cc test tube, add 
5 cc of alcoholic soda (see Reagents), boil vigorously for five minutes, 
add 40 cc of water, and mix; a clear solution indicates that not more 
than traces of unsaponifiable matter are present. If the i eters _ 
not clear, the oil is not pure linseed oil. 

(1) IoprineE Numper or Farry Acips.—Place a small qeaititd of 
the fatty acids, (g), in a small weighing burette or beaker. Weigh 
accurately. Transfer by dropping from 0.09 to 0.15 g into a 500 ce 
bottle having a well-ground glass stopper, or an Erlenmeyer flask 
having a specially flanged neck for the iodine test. Reweigh the 
burette or beaker and determine the amount of sample used. Add 
10 cc of chloroform. Whirl the bottle to dissolve the sample. Add 
10 cc of chloroform to each of two empty bottles like that used for 
the sample. Add to each bottle 25 ce of the Wijs solution (see 
Reagents) and let stand with occasional shaking for one hour in a 
dark place at a temperature of from 21 to 23°C. Add 10 ee of the 
15 per cent potassium iodide solution and 100 cc of water, and titrate 
with standard sodium thiosulphate, using starch as indicator. The 
titrations on the two blank tests should agree within 0.1 cc. From 
the difference between the average of the blank titrations and the 
titration on the sample and the iodine value of the thiosulphate 
solution, calculate the iodine number of the sample tested. (lodine 


SPECIFICATION FOR OLIVE DRAB PAINT 7 


number is centigrams of iodine to 1 g of sample.) If the iodine 
number is less than 175, the oil does not meet the specification. 

(7) Coarse Partictes anp Sxins.—Dry in an oven at 105 to 
110° C. a No. 325 sieve, cool, and weigh accurately. Weigh an 
am punt of semipaste containing 10 ¢ of pigment (See VI, 2 (f)), add 
100 cc of kerosene, mix thoroughly, and wash with kerosene through 
the sieve, breaking up all lumps, but not grinding. After washing 
with kerosene until all but the particles too coarse to pass the sieve 
have been washed through, wash all kerosene from the sieve with 
ether or petroleum ether, heat the sieve and contents for one hour at 
105 to 110° C., cool and weigh. 


3. ANALYSIS OF PIGMENT 


(a) QuaLITATIVE ANALyYsIs.—A complete qualitative analysis, fol- 


lowing the well-established methods, is always advisable. Test a 


portion of the pigment with hydrochloric acid (1:1). No odor of 
hydrogen sulphide should develop. Boil, dilute, filter, and test 
the filtrate for metals other than lead and zinc (especially calcium 
and barium). The absence of calcium in this filtrate indicates that 
the extending pigments contain no calcium carbonate or calcium sul- 
phate; the absence of barium indicates that the extending pigments 
contain no barium carbonate. To test for chromate, boil another 
small portion of the pigment with dilute nitric acid, filter, cool, and 
add to the filtrate a few cubic centimeters of ether and a few drops of 
hydrogen peroxide; stir, let stand until the ether layer separates. If 
this layer is deep blue, chromium is indicated. Test for Prussian blue 
(which is rarely present) by boiling a portion of the pigment with 
sodium hydroxide solution. A yellow or yellow-brown precipitate 
with a yellow liquid above it should result. Filter, add to the 
filtrate a mixture of ferric and ferrous salts, and render acid with 
dilute hydrochloric acid. A blue color indicates the presence of 
Prussian blue in the sample. 

(6) Waitt Leav.—Weigh accurately about 1 g of the pigment, 
transfer to a 250 cc beaker, moisten with a few drops of alcohol, add 
slowly 25 cc of concentrated hydrochloric acid, cover, and boil for 
5 to 10 minutes. Dilute to about 150 cc with hot water and boil 
for 5 to 10 minutes. Filter on paper or on a Gooch crucible, and 
wash the insoluble residue thoroughly with hot water. Discard the 
residue for quantitative purposes. Nearly neutralize with ammonia 
the filtrate from the insoluble matter, dilute to about 300 cc and pass 
into the clear solution a rapid current of hydrogen sulphide to com- 
plete precipitation, let the sulphide of lead settle, filter on paper, 
wash with water containing some hydrogen sulphide, dissolve the 
sulphide in hot nitric acid (1:3), add 10 cc of sulphuric acid (1:1), 
evaporate until copious fumes of sulphuric anhydride are evolved; 


8 CIRCULAR OF THE BUREAU OF STANDARDS 


cool, add about 75 cc of water, and then about 75 cc of 95 per cent 
ethyl alcghol. Stir, let settle, filter on a Gooch crucible, wash with 
dilute alcohol, dry, ignite, and weigh as PbSO,. Subtract the lead 
sulphate equivalent of the total chromium as found below, (c), multi- 
ply the remaining PbSO, by the factor 0.883 and report as white lead. 

(c) Toran CHromium.—Heat the filtrate from the lead sulphide 
to expel hydrogen sulphide.. Cool, add sodium peroxide, keeping the © 
beaker covered, in sufficient amount to render the solution alkaline ~ 
and to oxidize the chromium to chromate. Boil until all the hydro- 
gen peroxide is driven off, cool, acidify with sulphuric acid (1:4), 
add a measured excess of a freshly prepared solution of ferrous sul- 
phate, and titrate the excess of ferrous iron with standard potassium 
dichromate, using potassium ferricyanide solution as outside indica- 
tor. Titrate a blank of an equal volume of the ferrous sulphate solu- 
tion with the standard potassium dichromate. From the difference 
between the titration on the blank and on the sample, calculate the 
chromium in the sample to PbCrO,. From the PbCrO, found, cal- 
culate the equivalent. of PbSO, by multiplying by the factor 0.938. 

(<4) Zinc Oxipn.—Weigh accurately about 1 g of the pigment, 
transfer to a 250 cc beaker, moisten with alcohol, add 30 ce of hydro- 
chloric acid (1:2), boil for two or three minutes, add about. 100 
cc of water, let settle, and filter on paper; to the filtrate add about 
2 g of ammonium chloride and strong ammonia. until slightly alka- 
line (the latter to precipitate out any iron present), set on the steam 
bath to settle, filter into a 400 cc beaker, wash the precipitate once 
with water, remove the beaker and dissolve the iron hydroxide 
with dilute hydrochloric acid, catching the ferric chloride in a 250 
cc beaker, add to this filtrate 1 g of ammonium chloride and make 
ammoniacal, let settle, filter and wash thoroughly with hot water, 
catching the filtrate and washings in the original 400 cc beaker, 
reserved from the first precipitation. Add a small piece of litmus 
paper. Render the filtrate first acid with hydrochloric acid, then 
add 3 cc of strong hydrochloric acid, heat nearly to boiling, and 
titrate with standard ferrocyanide, as in standardizing that solution 
(see Reagents). Calculate total zinc as zinc oxide. 

(e) Organic Cotorine Marrer.—(A. S. 7. M. Standards, 1921, 
».690.)—Test the pigment successively with hot water, 95 per cent 
alcohol, alcoholic sodium hydroxide, and acetic acid. Chloroform, 
sodium hydroxide, sulphuric acid, hydrochloric acid-stannous chloride 
solution, and other reagents may be tried. The solutions should 
remain colorless. The presence of an organic color may. often be 
detected by the characteristic, odor given off on ignition. — 

(f) CaucuLations.—Add the percentage of white lead (see VI, 3, 
(b)), zine oxide (see VI, 3, (d)), and subtract from 100; the remain- 
der is reported as extending and tinting pigment. ' 


Se ee Se ee eee Se 


a ee ee 


Pe) aera een ee eS ee 


SPECIFICATION FOR OLIVE DRAB PAINT 9 
4, LABORATORY EXAMINATION, READY-MIXED PAINT 


(a2) Caxine 1n Contarner.—Follow the procedure outlined in 
VI, 2 (a), noting that the paint should be no more difficult to break 
up than a good grade of mixed paint. 

(6) Wxicut PER GaLton.—Weigh a clean, dry, 100 cc graduated 
flask. Fill to the mark with the thoroughly mixed paint and weigh 
again. The increase in weight expressed in grams divided by 100 
gives the specific gravity, which multiplied by 8.33 gives the weight 
in pounds per gallon. 

(c) BrusHinc Propertizs anp Time or Dryine.—Brush this 
well-mixed paint on a suitable panel, which may be ground glass, 
steel, or well-filled wood. Note whether the paint works satis- 
factorily under the brush. Place the panel in a vertical position 
in a well-ventilated room and let stand for 18 hours. The paint 
should be dry and free from streaks. Flow a portion of the paint 
on a clean glass plate. Let dry in a nearly vertical position at room 


temperature (65 to 100° F.). The film shall show no streaking or 


separation within a distance of 4 inches from the top. 

“(d) Cotor.—Paint the sample and the standard on clean metal 
or glass so that the edges touch one another. Let dry and compare 
colors. 

(ec) WarEer.—Mix 100 g of the paint in a 500 cc short neck glass 
flask! with 75 cc of toluol (free from water). Connect with the dis- 
tilling trap and condenser and heat so that the condensed distillate 
falls from the end of the condenser at the rate of from two to five 
drops per second. Continue the distillation at the specified rate 
until no water is visible on any part of the apparatus except at the 
bottom of the trap. This operation usually requires less than an 
hour. A persistent ring of condensed water in the condenser tube 
should be removed by increasing the rate of distillation for a few 
minutes. The number of cubic centimeters of condensed water 
measured in the trap at room temperature is the percentage of water 
in the paint. 

(f) Vouatits Tutnner.—Follow the procedure outlined in VES 
(e). Correct the result for any water found (see VI, 4 (e)) and re- 
port the remainder as volatile thinner. 

(g) Percentacs or Piement.—Follow the procedure outlined in 
VI, 2, (f). 

(h) Tustinc Nonvouatite Veuicte.—Follow the procedure out- 
lined in V, 2 (g), (4), and (i), except that in the preparation of the 
fatty acids the mixture of paint and alkali is heated on the steam 
bath until all volatile thinner is driven off. 

1 The apparatus for determining water is that described in ‘Standard method of test for water in petro- 


leum products and other bituminous materials,” serial designation D-95-24, A. 8. T. M. Standards, 1924, 
p. 901 and Figure 1 (6) and (¢), p. 902. 


10 CIRCULAR OF THE BUREAU OF STANDARDS 


(2) Coarse Particues anp Sxins.—Follow the procedure outlined 
in VI, 2 (9). 
(Gj) Testine Prement.—Follow the procedure outlined in VI, 3 (a) 


to (f), inclusive. 
5. REAGENTS 


(a) Uranyy InpicaTor ror Zinc Titration.—A 5 per cent solu- 
tion of uranyl nitrate in water or a 5 per cent solution of uranyl 
acetate in water made slightly acid with acetic acid. 

(6) Sranparp Potassium FrrrocyanipE.—Dissolve 22 g of the 
pure salt in water and dilute to 1,000 cc. To standardize, transfer 
about 0.2 g (accurately weighed) of pure metallic zinc or freshly 
ignited pure zinc oxide to a 400 cc beaker. Dissolve in 10 cc of 
hydrochloric acid and 20 cc of water. Drop in a small piece of litmus 
paper, add ammonium hydroxide until slightly alkaline, then add 
hydrochloric acid until just acid, and then 3 cc of strong hydrochloric 
acid. Dilute to about 250 cc with hot water and heat nearly to 
boiling. Run in the ferrocyanide solution slowly from a burette 

with constant stirring until a drop tested on a white porcelain plate 
" with a drop of the uranyl indicator shows a brown tinge after standing 
one minute. A blank should be run with the same amounts of 
reagents and water as in the standardization and in titration of the 
sample. The standardization must be made under the same condi- 
tions of temperature, volume, and acidity as obtained when inp 
sample is titrated. 

(c) StaNDARD Sopium THIOSULPHATE SOLUTION. Dimes pure 
sodium thiosulphate in distilled water (that has been well boiled to 
free it from carbon dioxide) in the proportion of 24.83 g of crystal- 
lized sodium thiosulphate to 1,000 cc of the solution. It is best to 
let this solution stand for about two weeks before standardizing. 
Standardize with pure resublimed iodine. (See Treadwell-Hall, 
Analytical Chemistry, vol. 2, 6th ed., p. 551.), This solution will be 
approximately decinormal, and it is best to leave it as it is after 
determining its exact iodine value, rather than to attempt to adjust 
it to exactly decinormal. Preserve in a stock bottle provided with 
a guard tube filled with soda lime. 

(d) Strarcu Sotution.—Stir up 2 to 3 g of noha BNR or 5 g 
of soluble starch with 100 cc of 1 per cent salicylic acid solution, 
add 300 to 400 cc of boiling water, and boil the mixture untit the 
starch is practically dissolved, then dilute to 1 liter. 

(e) Extraction Mixtrurs.— 

10 volumes ether (ethyl ether). 
6 volumes bénzol. 

4 volumes methyl alcohol. 

1 volume acetone. 


a ee Se Le a ee A ae Se ll 


SPECIFICATION FOR OLIVE DRAB PAINT 11 


(f) Aqgurnous Soprum Hyproxinz.—Dissolve 100 ¢g of sodium hy- 
droxide in distilled water and dilute to 300 ce. 
(g) Porasstum lopipr So.tution.—Dissolve 150 g of potassium 


‘iodide free from iodate in distilled water and dilute to 1,000 cc. 


(h) Wiis Sotution.—The preparation of the iodine monochloride 
solution presents no great difficulty, but it should be done with care 
and accuracy in order to obtain satisfactory results. There shall be 
in the solution no sensible excess either of iodine or more particularly 
of chlorine over that required to form the monochloride. This con- 
dition is most satisfactorily attained by dissolving in the whole of 
the acetic acid to be used the requisite quantity of iodine, using 


gentle heat to assist the solution, if it is found necessary. Dissolve 


iodine in glacial acetic acid that has a melting point of 14.7 to 15° C. 
and is free from reducing impurities in the proportion so that 13 ¢g 
of iodine will be present in 1,000 cc of solution. Set aside a small 
portion of this solution while pure, and pass dry chlorine into the 
remainder until the halogen content of the solution is doubled. 
Ordinarily it will be found that by passing the chlorine into the 
main part of the solution until the characteristic color of free iodine 
has just been discharged, there will be a slight excess of chlorine 
which is corrected by the addition of the requisite amount of the 
unchlorinated portion until all free chlorine has been destroyed. A 
slight excess of iodine does little or no harm, but excess of chlorine 
must be avoided. 

(1) Anconotic Sopium Hyproxipr SoivutTion.—Dissolve pure 
sodium hydroxide in 95 per cent ethyl alcohol in the proportion of 
about 22 g per 1,000 cc. Let stand in a stoppered bottle. Decant 
the clear liquid into another bottle and keep well stoppered. This 
solution should be colorless or only slightly yellow when used, 
and it will keep colorless longer if the alcohol is previously treated 
with sodium hydroxide (about 80 g to 1,000 cc), kept at about 
50° C. for 15 days, and then distilled. 

(7) StaNDARD Frrrovus SuntpHate Souution.—Dissolve 14 g 
of pure crystallized ferrous sulphate (FeSO,7H.O) in about 500 
cc of water to which 25 cc of concentrated H,SO, has been added, 
and then dilute to 1,000 cc. This solution should be freshly stand- 
ardized when needed, as it does not keep well. 

(ek) StanpaRD Porasstum DicHromMatTE So.utrion.—Dissolve 
4.903 g of pure, dry, crystallized potassium dichromate in water 
and dilute to 1,000 cc. One cubic centimeter of this solution corre- 
sponds to 0.0108 g PbCrQ,, or 0.0101 g PbSO,. This solution may 
be checked by determining its iron value on Bureau of Standards 
Standard Sample No. 27a, Sibley Iron Ore. 


12 CIRCULAR OF THE BUREAU OF STANDARDS 


(7) Porasstum Frrricyanripr SoLtutTion.—Dissolve a piece of 
potassium ferricyanide half as big as a small pea in 50 cc of water. 
This solution must be made fresh when wanted, because it does not 
keep. ease : 


VII. PACKING AND MARKING OF SHIPMENTS ibe 


Shall be in accordance with commercial practice unless otherwise 
specified. 
VIII. NOTES 


This specification covers the requirements for a high-grade olive- 
drab paint for outside and general use. It may be ordered either in 
the form of semipaste pigment ground in linseed oil or of ready- 
mixed paint, and the purchaser shall state which is desired. The 
semipaste may be purchased by net weight or by volume. The 
ready-mixed paint should be purchased by volume (231 cubic inches 
to the gallon). ? 

For formulas and methods of using this material and information 
regarding the use of other specification paint materials see Bureau 
of Standards Technologic Paper No. 274, entitled “Use of United 
States Government Specification Paints and Paint Materials,” 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 


§ CENTS PER COPY 
Vv 


U. S. Gov't 
Master 
Specification 


No. 278 
DEPARTMENT OF COMMERCE 


BUREAU OF STANDARDS 
George K. Burgess, Director 


CIRCULAR OF THE BUREAU OF STANDARDS, No. 215 
{Issued May 9, 1925] 


UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
OUTSIDE WHITE TITANIUM-ZINC PAINT, SEMIPASTE AND 
READY-MIXED 


FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 278 


This specification was officially promulgated by the Federal Specifications 
Board on May 8, 1925, for the use of the Departments and Independent 
Establishments of the Government in the purchase of outside white titanium- 
zinc paint, semipaste and ready-mixed. 


CONTENTS 
Page 
TAG dey GS A, per te a, LN Se OP ee ey aR ee ane 1 
I anc tei pchln os aie ic aos ainda ee od 2 
Mee) CEU TENT CXR OVN So a ro ae emp melas y 4 
Se NEUE RL RST EATS COTTA i a cere aes pt diigo es alll ld ene y 
: bE) aR ee SN Aegean ay eS ee AO ANSE Sere Sine A Ae ee ae NE 2 
A a Sash le ons Pea tamale eed eho Sd ih ene 2 
permrrenaye rin eile es Oe es as ee a ee lay i Z 
marenuyanited paints S25.) ee ee ewe ee 3 
eeetnome or semnling and testing... <n. obec ee ate ee en 3 
0 DESO 96) GRO Sie ACS SERRE Ge ee Ra Oa ae oe Ae cee ps ae 3 
2. Laboratory examination, semipaste___._______.___________ 4 
sana lyoie Of pitnetit. Ursi ie 23 le Ae Se ie 6 
4, Laboratory examination, ready-mixed paint______________ 8 
Shia OTE 2 i id oh en iio i i peed 10 
SR SIE Sele ce Dd 9b 1 gat RnR, SiR egaRON pec i Sar NOE eae aan a MEN Se 12 
Mtr SePraCLAT AOL ETOEINA CLOT oe ee ees 12 
WORE ET PIE SCC ITIOR LIOLIS cies ke a Sm pe a ep nh et oe wel 12 


I. CLASSES 


Outside white titanium-zinc paint shall be of the following classes: 
Semipaste in linseed oil and ready-mixed. 
43781°—25 


2 CIRCULAR OF THE BUREAU OF STANDARDS 
Il. MATERIAL 
No details specified. 
III. GENERAL REQUIREMENTS 
No details specified. 
IV. DETAIL REQUIREMENTS 
1. PIGMENT 


_ The pigment shall be composed of: 


Ingredients 


fxtending Pigments, 5... sc.05.0hhnahstendases 5 dbas == Skee a ae 


ean eee eee ee Oe we ee RH EO ee RE ES SR RE eee 


In no case shall the sum of the titanium pigment and zine oxide 
be less than 90 per cent. The titanium pigment shall contam 25 
per cent titanium oxide, the remainder to be blanc fixe (precipi- 
tated barium sulphate). 


2. LIQUID 


The liquid in semipaste paint shall be entirely linseed oil; in 
ready-mixed paint it shall contain not less than 85 per cent linseed 
oil, the remainder to be combined drier and thinner. The drier 
shall be free from lead. The thinner shall be turpentine, volatile 
mineral spirits, or a mixture thereof. “rs 


3. SEMIPASTE 


Semipaste shall be made by thoroughly grinding the pigment 
with linseed oil. 

The semipaste as received, and three months thereaiter, shall be 
not caked in the container and shall break up readily in linseed 
oil to form a smooth paint of brushing consistency. It shall mix 
readily with linseed oil, turpentine, or volatile mineral spirits or 
any combination of chase substances, in all proportions without 
curdling. The color and hiding power when specified shall be equal 
to those of a sample mutually agreed upon by buyer and seller. 
The weight per gallon shall be not less than 1714 pounds. The 
semipaste shall consist of; 


eS. hl Ae = 


OUTSIDE WHITE TITANIUM-ZINC PAINT 8 


Ingredients Maximum | Minimum 


Per cent Per cent 
75 


1 AE a 3S ASR. SE Sa a et ea art ae neteies Peal et 70 
NE NE EO ark Ci Ss CaM w oid ena nt hc. cater o®aedoaldcwaata 30 25 
Romer Wy TCIM Stree Aire ee ee ee es ea en ae ee ee NOn6. 1... cakecaties 
Moisture and other volatile matter Pe ad oie Sane Le aee soa eae eGn See boaete steep ot OST (acess. Se 
Coarse particles and ‘‘skins’”’ (total residue retained on No. 325 sieve based on 

CE gE SE DID. EE Sy OE TER Say A Sn ee eee VM Mig SAP Senay, ego 


4. READY-MIXED PAINT 


Ready-mixed paint shall be well ground, shall not settle badly 
or cake in the container, shall be readily broken up with a paddle 
to a smooth, uniform paint of good brushing consistency, and shall 
dry within 18 hours to a full oil gloss, without streaking, running, 
or sagging. The dried film shall be resistant to sulphide fumes. 
The color and hiding power when specified shall be equal to those 
of a sample mutually agreed upon by buyer and seller. The weight 
per gallon shall be not less than 14 pounds. The paint shall con- 
sist of : 


Ingredients Maximum | Minimum 


Per cent Per cent 
OUTS STG SU SDD oO Oe en aR ae en etre a 62 58 


Liquid Csaatatgtae at least 85 per cent linseed Onpisreee ) SONS a ek PLES 42 38 
NE SEIS Sep eR SOPRA tas ip eT oe eS eee N anes ae. Na oe 
PRM eneE soe weet oe ae eel NS Ere SL as A ee cits’ 2G BT eee 


Coarse particles and ‘‘skins’”’ (total residue retained on No. 325 sieve based on 


jus | SRG) boats DSU RE ae he wae) See COS Meo D8 eee ae oD Le ee On LE Ieee. SD | dukteccalpe 


V. METHODS FOR SAMPLING AND TESTING 


Delweries will, in general, be sampled and tested by the following 
methods, but the purchaser reserves the right to use any additional 


available information to ascertain whether the material meets the 


specifications. 
1, SAMPLING 


It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1,000 packages shall be taken as 
representative of the whole. Whenever possible an original un- 
opened container shall be sent to the laboratory, and when this is for 
any reason not done, the inspector shall determine by thorough 
testing with a paddle or spatula whether the material meets the 
requirement regarding caking in the container. We shall then thor- 
oughly mix the contents of the container and draw a sample of not 
less than 5 pounds of the thoroughly mixed paint, place it in a 
clean, dry metal or glass container, which must be filled with the 
sample, closed with a tight cover, sealed, marked, and sent to the 


laboratory for test with the inspector’s report on caking in con- 


4 CIRCULAR OF THE BUREAU OF STANDARDS 


tainer. When requested, a duplicate sample may be taken from 
the same package and delivered to the seller, and the inspector may 
take a third sample to hold for test in case of dispute. 


2. LABORATORY EXAMINATION, SEMIPASTE 


(az) Caxrne in Contatner.—When an original package is received 
in the laboratory it shall be weighed, spend and stirred with a 
stiff spatula or paddle. The paste must be no more difficult to 
break up than a normal good grade of semipaste paint. The semi- 
paste shall finally be thoroughly mixed, removed from the container, 
and the container wiped clean and weighed. This weight subtracted 
from the weight of the original package gives the net weight of the 
contents. A portion of thoroughly mixed semipaste shall be placed 
in a clean container and the portions for the remaining tests pr omptly 
weighed out. 

(6) Wricur per Gatton.—From the weight of a known volume 
of the paste calculate the specific gravity, which multiphed by 8.33 
gives the weight in pounds per gallon. Any suitable container of 
known volume may be used for the purpose, but a short cylinder of 
heavy glass with rounded bottom about 75 mm high and having 
a capacity of from 125 to 175 cc (a glass cap to keep dust from 
reagent bottle stopper) is a convenient vessel for the purpose. The 
capacity of this vessel is determined to within 1 ec. The paste is 
packed into it until completely full, the top leveled off smooth with 

a spatula, and weighed to plus or minus 0.5 g. Subtract the weight 
of the empty container and divide the remainder by the canes of 
cubic centimeters representing the capacity of the container. The 
quotient is the specific gravity, which can be thus Tt npn 
plus or minus 2 in the second decimal place. 

(c) Mrxinc Wirn Linszep Om.—One hundred gen of ‘the 
paste shall be placed in a cup, 18 cc of linseed oil added slowly with 
careful stirring and mixing with a spatula or paddle. The resulting 
mixture must be smooth ad of good brushing consistency. _ 

(d) Cotor.—Place some of the paste on a clean, clear glass plate. 
Place some of the standard agreed upon beside the sample on the 
plate, turn the glass over, and compare the colors. 

(e) Moisture AND Oral. Voratite Marrer.—Weigh accurately 
from 8 to 5 g of the paste in a tarred flat-bottomed dish about 8 cm 
in diameter, spreading the paste over the bottom. Heat at 105 to 
110° C. for three hours, cool, and weigh. Calculate the loss in weight 
as the percentage of moisture and volatile matter. 

(f) Percentace or Pigment.—Weigh accurately about 15. g of 
the paste in a weighed centrifuge tube. Add 20 to 30 ce of “ex- 
traction mixture” (see Reagents), mix thoroughly with a glass rod, 
wash the rod with more of the extraction mixture, and add enough: 


io 


ETO Pe ae ee Sen I ee ee ee 


OUTSIDE WHITE TITANIUM-ZINC PAINT 5 


of the reagent to make a total of 60 cc in the tube. Place the tube 
in the container of a centrifuge, surround with water, and counter- 
balance the container of the opposite arm with a similar tube or a 
tube with water. Whirl at a moderate speed until well settled. De- 
cant the clear supernatant liquid, repeat the extraction twice with 40 
cc of extraction mixture and once with 40 cc of ether. 

After drawing off the ether, set the tube in a beaker of water at 
about 80° C. or on top of a warm oven for 10 minutes, then in an 
oven at 105 to 110° C. for two hours. Cool, weigh, and calculate 
the percentage of pigment. Grind the pigment to a fine powder, 
pass through a No. 80 sieve to remove any skins, and preserve in a 
stoppered bottle. 

(g) Preparation or Farry Aciwns.—To about 25 g of the paste 
in a porcelain casserole, add 15 ce of aqueous sodium hydroxide (see 
Reagents) and 75 cc of ethyl alcohol, mix and heat uncovered on 
a steam bath until saponification is complete (about one hour). Add 
100 ce of water, boil, add sulphuric acid of specific gravity 1.2 (8 to 
10 ce in excess), boil, stir, and transfer to a separatory funnel to 
which some water has been previously added. Draw off as much as 
possible of the acid aqueous layer, wash once with water, then add 
50 cc of water and 50 cc of ether. Shake very gently with a whirl- 
ing action to disolve the fatty acids in the ether, but not so vio- 
lently as to form an emulsion. Draw off the aqueous layer and wash 
the ether layer with one 15 cc portion of water and then with 5 cc 
portions of water until free from sulphuric acid. Then draw off the 
water layer completely. Transfer the ether solution to a dry flask 
and add 25 to 50 g of anhydrous sodium sulphate. Stopper the 
flask and let stand with occasional shaking at a temperature below 
25° ©. until the water is completely removed from the ether solution, 
which will be shown by the solution becoming perfectly clear above 
the solid sodium sulphate. Decant this clear solution, if necessary, 
through a dry filter paper into a dry 100 cc Erlenmeyer flask. Pass 
a. rapid current of dry air (pass through a CaCl, tower) into the 
mouth of the Erlenmeyer flask and heat to a temperature below 
75° ©. on a dry, hot plate until the ether is entirely driven off. 

It is important to follow all of the details, since ether generally 
contains alcohol, and after washing with water always contains 
water. It is very difficult to remove water and alcohol by evapora- 
tion from fatty acids, but the washing of the ether solution and sub- 
sequent drying with anhydrous sodium sulphate removes both water 
and alcohol. Ether, in the absence of water and alcohol, is easily 
removed from fatty acids by gentle heat. 

The fatty acids prepared as above should be kept in a stoppered 
flask and examined at once. __ 


6 CIRCULAR OF THE BUREAU OF STANDARDS 


(h) Test ror Mrnerat Om ann Orser UNSAPONIFIABLE Mar- 
TER.—Place 10 drops of the fatty acid (g), in a 50 cc test tube, add 
5 cc of alcoholic soda (see Reagents), boil vigorously for five min- 
utes, add 40 cc of water, and mix; a clear solution indicates that 
not more than traces of unsaponifiable matter are present. If ail 
solution is not clear, the oil is not pure linseed oil. 

(¢) Ioprne Nita or Farry Actips.—Place a small dannttty of 
the fatty acids (g) in a small weighing burette or beaker. Weigh 
accurately. Transfer by dropping about 0.15 g (0.10 to 0.20 g) into 
a 500 ce bottle having a well-ground glass stopper, or an Erlen- 
meyer flask having a specially flanged neck for the iodine test. Re- 
weigh the burette or beaker and determine the amount of sample 
used. Add 10 ce of chloroform. Whirl the bottle to dissolve the 
sample. Add 10 ec chloroform to two empty bottles like that 
used for the sample. Add to each bottle 25 cc of the Hanus solu- 
tion (see Reagents) and let stand with occasional shaking’ for one- 
half hour. Add 10 cc of the 15 per cent potassium iodide solution 
and 100 ec of water, and titrate with standard sodium thiosulphate, 
using starch as indicator. The titrations on the two blank tests 
should agree within 0.1 cc. From the difference between the aver- 
age of the blank titrations and the titration on the sample and the 
iodine value of the thiosulphate solution, calculate the iodine number 
of the sample tested. (Iodine number is centigrams of iodine to 1 g 
of sample.) If the iodine number is less than 170, the oil does not 
meet the specification. 

(7) Coarsk Partictrs AND SKINS. Dry in an oven at 105 to 
110° C. a No. 325 sieve, cool, and weigh accurately. Weigh an 
amount of semipaste cdmtinibitee! 10 g of pigment (see V, 2, (f), add 
100 ce of kerosene, mix thoroughly, and wash with kerosene through 
the sieve, breaking up all lumps, but not grinding. After wash- 
ing with kerosene until all but the particles too coarse to pass the 
sieve have been washed through, wash all kerosene from the sieve 
with ether or petroleum ether, heat the sieve and contents for one 
hour at 105 to 110° C., cool and weigh. 


3. ANALY RS OF PIGMENT 


(a) QUALITATIVE een —Make qualitative analysis “FolLDeEAY 
ordinary methods. The pigment should show negative test for sul- 
phide sulphur and appreciable water-soluble matter; ash a sample of 
the semipaste or ready-mixed paint and test for ‘aaa? 

(6) Marrer Sotuste In Warer.—Transfer 2.5 g of the pigment 
to a graduated 250 cc flash, add 100 cc of water, boil for five min- 
utes, cool, fill to the mark with water, mix, and allow to settle. 
Pour the supernatant liquid through a dry filter paper and discard 


eS 


% 
{ 
j 
i: 
; 
> 

4 

| 


OUTSIDE WHITE TITANIUM-ZINC PAINT 7 


the first 20 cc. Then evaporate 100 cc of the clear filtrate to dry- 
ness in a weighed dish, heat for one hour at 105 to 110° C., cool and 
weigh. 

(¢) Trranrom Oxmr—wWeigh accurately about 1 g of the pig- 
ment, transfer to a 250 cc Pyrex beaker, add 25 cc of concentrated 
sulphuric acid and 8 g of ammonium sulphate. Mix well and heat 
on a hot plate until fumes of sulphuric acid are evolved, and then 


‘ continue the heating over a strong flame until solution is complete 


(usually not over five minutes of boiling) or it is apparent that the 
residue is composed of silica or siliceous matter. Caution should 
be observed in handling this hot acid solution. Cool the solution, 
dilute with 100 cc of water, stir, heat carefully to boiling while 
stirring, settle, filter through paper and transfer the precipitate com- 
pletely to the paper. Wash the insoluble residue with cold 5 per cent 
(by volume) sulphuric acid until titanium is removed. 

Dilute the filtrate to 200 cc and add about 30 cc of ammonia, 
specific gravity 0.90, to lower the acidity to approximately 5 per 
cent sulphuric acid (by volume). 

Wash out a Jones reductor’? with dilute 5 per cent (by Ponttiey 
sulphuric acid and water, leaving sufficient water in the reductor to 
fill to the upper level of the zinc. (These washings should require 
not more than one or two drops of 0.1 WV potassium permatganate 
solution to obtain the pink color.) Empty the receiver, and put in 
it 25 cc (measured in a graduate) of ferric sulphate solution. (See 


Reagents.) Reduce the prepared titanium solution as follows: (1) 


Run 50 ce of the 5 per cent sulphuric acid solution through the 
reductor at a speed of about 100 cc per minute, (2) follow this with 
the titanium solution, (3) wash out with 100 cc of 5 per cent sul- 
phuric acid, (4) finally run through about 100 ce of water. 

Care should be observed that the reductor is always filled with 
solution or water to the upper level of the zinc. 

Gradually release the suction, wash thoroughly the glass tube that 
was immersed in the ferric sulphate solution, remove the receiver, 
and titrate immediaely with 0.1 V potassium permanganate solution. 
(See Reagents.) 


tec 0.1 V KMn0,=0.00481 g Ti=0.00801 ¢ TiO, 


Run a blank determination, using the same reagents, washing the 
reducer as in the above determination. Subtract this permanganate 
reading from the original reading and calculate the final reading to 
titanium dioxide (TiO,) (which will include iron, chromium, 
arsenic, and any other susbtance which is reduced by zine and acid). 


2 Directions for preparing a Jones reductor may be found in Blair, The Chemical 
Analysis of Iron, 8th ed., Lippincott & Co., or Treadwell-Hall, Analytical Chemistry, 5th 
ed., J. Wiley & Sons, p. 368. 


8 CIRCULAR OF THE BUREAU .OF STANDARDS 


(7d) Bartum SuipHate.—Ignite and weigh the insoluble matter 
obtained in separating the titanium (see V, 3, (c)). Mix the ignited 
residue with about 10 times its weight of anhydrous sodium car- 
bonate (grind the mixture in an agate mortar if necessary), fuse the 
mixture in a covered platinum crucible, heating about one hour. 
Let cool, place the crucible and cover in a 250 cc beaker, add about 
100 ce re water, and heat until the melt is disintegrated. Filter on 
paper (leaving the crucible and cover in the beaker) and wash the 
beaker and filter thoroughly with hot water to remove soluble sul- 
phates. Place the beaker containing the crucible and cover under 
the funnel, pierce the filter with a glass rod, and wash the carbonate 
residue into the beaker by means of a jet of hot water. Wash the 
paper with hot dilute hydrochloric acid (1:1), and then with hot 
water. If the carbonate residue is not completely dissolved, add 
sufficient dilute hydrochloric acid to effect solution, and remove the 
crucible and cover, washing them with a jet of water. Heat the 


solution to boiling and add 10 to 15 cc of dilute sulphuric acid, and — 


continue the boiling for 10 or 15 minutes longer. Let the precipitate 
settle, filter on a weighed Gooch crucible, wash with hot water, 
ignite, cool, and weigh as BaSO,. Subtract the result from the 
original nate nhs to obtain the siliceous material. 

(2) Zinc Oxipz.—Weigh accurately about 0.5 g of the aoe 
transfer to a 400 ce beaker, add 30 cc of hydrochloric acid (1: 2), 
boil for two or three minutes, add 200 ce of water and a small piece 


of litmus paper; add strong ammonia until slightly alkaline, render 


just acid with hydrochloric acid, then add 38 ce of strong hydro- 
chloric acid, heat nearly to boiling, and titrate with standard ferro- 
cyanide as in standardizing that solution (see Reagents). Calculate 
total zinc as zinc oxide. Las 

(f) CatcuLations.—In case the percentage of barium sulphate 
(V, 8, (d@)) is not more than 3.17 times as great as the percentage 
of titanium oxide (V, 3, (¢)), add the two together and call the sum 
the percentage of titanium pigment. If the percentage of barium 
sulphate is greater than this amount, take 3.17 times the percentage 
of titanium oxide as the percentage of barium sulphate to be included 
in the percentage of titanium pigment and include the remainder 
in the percentage of extending pigments. Subtract the sum of the 
percentages of titanium pigment, zinc oxide (V, 3, (¢)), and matter 
soluble in water (V, 8, (6)) from 100. Call the remainder percent- 
age of extending pigments. 


4. LABORATORY EXAMINATION, READY-MIXED PAINT 


(a) Caxine In Conratner.—Follow the procedure outlined in 
V, 2, (a), noting that the paint should be no more difficult to break 
up edie a good grade of mixed paint. 


# 


OUTSIDE WHITE TITANIUM-ZINC PAINT 9 


(b) Wetcur per Garton.—Weigh a clean, dry, 100 cc graduated 
flask. Fill to the mark with the thoroughly mixed paint and weigh 
again. The increase in weight expressed in grams divided by 100 
gives the specific gravity, which multiplied by 8.33 gives the weight 
in pounds per gallon. 

(c) Brusaine Properties anp Timz or Dryine.—Brush this well- 
mixed paint on a clean tin plate panel. Note whether the paint 
works satisfactorily under the brush. Place the panel in a vertical 
position in a well-ventilated room and let stand for 18 hours. The 
paint should be dry and free from streaks. Flow a portion of the 
paint on a clean glass plate. Let dry in a nearly vertical position at 
room temperature: (65 to 100° F.). The film shall show no streak- 
ing or separation within a distance of 4 inches from the top. 

(d) Restsrance to SunpHine Fumes.—Apply a suflicient number 
of coats of the paint to two glass plates to completely hide the sur- 
face, and expose one of the plates in a saturated atmosphere of 
hydrogen sulphide for 18 hours. Compare the color with the un- 
exposed plate. The exposed plate should be practically no darker 
than the unexposed one. There shall be no greater difference in the 
color of the two plates than there will be with similar plates coated 
with a paint made with titanium pigment, lead free zinc oxide, and 
raw or refined linseed oil with sufficient cobalt added for drying. 

(e) Cotor.—Paint the sample and the standard on clean metal or 
glass, so that the edges touch one another. Let dry and compare 
colors. ) 

) Warer.—Mix 100 g of the paint in a 250 or 300 ce flask with 
“5 cc of toluol. Connect with a condenser and distill until about 
50 cc of distillate has been collected in a graduate. The temperature 
in the flask should be then about 105 to 110° C. The number of 
cubic centimeters of water collecting under the toluol in the receiver 
is the percentage of water in the paint. 

4g) Voratin Tainner.—Follow the procedure outlined in V, 2, 
(e). Correct the result for any water found (see V, 4, (f)), and 
report the remainder as volatile thinner. 

(h) Percentace or Picment.—Follow the procedure outlined in 
V, 2, (f). 

, (4) Txstrxc NonvoaTILe Venicie.—Follow the procedure out- 

"lined in V, 2, (g), (4), and (é), except that in the preparation of 
the fatty acids the mixture of paint and alkali is heated on the steam 
bath until all volatile thinner is driven off. 

(j) Coarse ParTICLEs AND Sxrns.—Follow the procedure outlined 
in V, 2, (7). | , : 

(k) TEstTINe Picment.—Follow the procedure outlined in V, 3, 
(a) to (f), inclusive. 


10 CIRCULAR OF THE BUREAU OF STANDARDS 
5. REAGENTS 


(a) Uranyt Inprcator.—A 5 per cent solution of uranyl nitrate in 
water or a 5 per cent solution of uranyl acetate in water made 
slightly acid with acetic acid. 

(6) Sranparp Porasstum Frrrocyaniws.—Dissolve 22 g of the 
pure salt in water and dilute to 1,000 cc. To standardize transfer 
about 0.2 g (accurately weighed) of pure metallic zine or freshly 
ignited pure zinc oxide to a 400 cc beaker. Dissolve in 10 ce of 
hydrochloric acid and 20 cc of water. Drop in a small piece of 
litmus paper, add ammonium hydroxide until slightly alkaline, 
then add hydrochloric acid until just acid, and then 38 cc of strong 
hydrochloric acid. Dilute to about 250 ce with hot water and heat 
nearly to boiling. Run in the ferrocyanide solution slowly from a 
burette with constant stirring until a drop tested on a white porce- 
lain plate with’a drop of the uranyl indicator shows a brown tinge 
after standing one minute. A blank should be run with the same 
amounts of reagents and water as in the standardization and in 
titration of the sample. The standardization must be under the 
same conditions of temperature, volume, and acidity as obtained 
when the sample is titrated. 

(c) Sranparp Soprum. TurosutpHatTe SoLutron iD niles pure 
sodium thiosulphate in distilled water (that has been well boiled 
to free it from carbon dioxide) in the proportion of 24.83 g of 
crystallized sodium thiosulphate to 1,000 cc of the solution. It 
is best to let this solution stand for about two weeks before stand- 
ardizing. Standardize with pure resublimed iodine. This Solution 
will be approximately decinormal and it is best to leave it as it is 
after determining its exact iodine value, rather than to attempt to 
adjust it to exactly decinormal. Preserve in a stock bottle Aravieg 
with a guard tube filled with soda lime. 

(zd) Srarcu Sorutrion.—Stir up 3 g of potato Hine or 8 é of 
soluble starch with 100 cc of 1 per cent salicylic acid solution, add 
300 to 400 ec.of boiling water, and boil the mixture until the starch 
is practically dissolved, then dilute to 1 liter. Sore 

(e) Extraction Miieeeien — 

10 volumes ether (ethyl ether). | We 
6 volumes benzol. , ee 
4 volumes methyl alcohol. 
1 volume acetone. 


eae 
ait 


(f) Aqueous Soprum Hyproxinz.—Dissolve 100 g of. sodium 


hydroxide in distilled water and dilute to 300 ce. 
(7g) Porassrum Iopipz Sonurion.—Dissolve 150 g of. otassium 
iodide free from iodate in distilled water and dilute to 1,00 ce, 


2 Treadwell-Hall, Analytical Chemistry, 2, 6th ed., p. 551. 


| 
: 


OUTSIDE WHITE TITANIUM-ZINC PAINT 11 


(h) Hanus Sorution.—Dissolve 13.2 g of iodine in 1,000 cc of 
99.5 per cent glacial acetic acid, which will not reduce chromic acid. 
Add enough bromine to double the halogen content, determined 
by titration (3 cc of bromine is about the proper amount). The 
iodine may be dissolved by the aid of heat, but the solution should 
be cold when the bromine is added. 

(4) Auconoric Soprom Hyproxme Soxiurion.—Dissolve pure 
sodium hydroxide in 95 per cent ethyl alcohol in the proportion of 
about 22 g per 1,000 cc. Let stand in a stoppered bottle. Decant the 
clear liquid into another bottle and keep well stoppered. This solu- 
tion should be colorless or only slightly yellow when used, and it will 
keep colorless longer if the alcohol is previously treated with sodium 
hydroxide (about 80 g to 1,000 cc), kept at about 50° C. for 15 days, 
and then distilled. 

(7) 0.1 NV Porasstom Prermaneanate Sotution.—Dissolve 3.161 
g of pure potassium permanganate in a liter of distilled water, let 
stand 8 to 14 days, siphon off the clear solution (or filter through an 
asbestos filter), and standardize as follows: In a 400 cc beaker dis- 
solve 0.25 to 0.30 g of Bureau of Standards sodium oxalate in 250 
ce of hot water (80 to 90° C.) and add 15 cc of dilute sulphuric acid 
(1:1). Titrate at once with the potassium permanganate solution, 
stirring the liquid vigorously and continuously. The permanganate 
must not be added more rapidly than 10 to 15 cc per minute, and the 
last 0.5 to 1 cc must be added dropwise with particular care to allow 
each drop to be fully decolorized before the next is introduced. The 
solution should not be below 60°. C. by the time the end point is 
reached. (More rapid cooling may be prevented by allowing the 
beaker to stand on a small asbestos covered hot plate during the 
titration. The use of a small thermometer as a stirring rod is most 
convenient.) The weight of sodium oxalate used multiplied by 
0.8334 gives its iron equivalent, or multiplied. by 1.1954 gives its 
titanium dioxide (TiO,) equivalent.’ 

The permanganate solution should be kept in a glass-stoppered 
bottle painted black to keep out light. 

(%) Ferric Sutenate Sonurion.—A solution containing 2 per 
cent of iron as ferric sulphate is desired and may be prepared as 
follows: Dissolve 20 g of pure iron or plain carbon steel in a slight 
excess of hydrochloric acid, oxidize with nitric acid, heat with about 
80 cc of sulphuric acid until fumes are evolved, finally cool, and 
dilute to 1,000 ce set on steam bath, until dissolved, and filter if 
necessary. Add 0.1 V permanganate solution until a faint pink color 
shows that any ferrous iron has been oxidized. Ferric ammonium 
sulphate may also be used.‘ 

SESS ERE TS RG al ees En ee oe Ome a 
‘ sInternational Atomic Weights, 1925. 
«Gooch, Methods in Chemical Analysis, 1st ed., p. 426. 


12 ! CIRCULAR OF THE BUREAU OF STANDARDS 
VI. PACKING AND MARKING 
No details specified. ) 
VII ADDITIONAL INFORMATION 


This specification covers the requirements for a high-grade white 
paint for outside and general use, intended particularly to be used 
wherever excessive amounts of sulphide fumes would quickly discolor 
the average outside white paint. For marine use, the addition of 
1 pint of water-resisting spar varnish to each gallon of paint, just 
before application, is recommended. It may be ordered either in 
the form of semipaste pigment ground in linseed oil or of ready- 
mixed paint, and the purchaser shall state which is desired. 

The semipaste shall be purchased by net weight, and the ready- 
mixed paint either by weight or volume (231 cubic inches to the 
gallon). : 


VIII. GENERAL SPECIFICATIONS 


No details specified. 


ee 
ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C, 
AT 
5 CENTS PER OOPY 


Vv 


q 
: 
| 


U. S. Gov’t 
Master 
Specification 
No. 283 


DEPARTMENT OF COMMERCE 
BUREAU OF STANDARDS 
George K. Burgess, Director 


CIRCULAR OF THE BUREAU OF STANDARDS, No. 216 


[Issued May 9, 1925] 


UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
| PUTTY 


FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 283 


This specification was officially promulgated by the Federal Specifications 
Board on May 8, 1925, for the use of the Departments and Independent 
Establishments of the Government in the purchase of putty. 


CONTENTS 


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Were ee tattia) ITTOYTIATION. — 2 a ee et Sk ert 
Septsrreseereras Speciiications.2 oo ae ei i es 


I. CLASSES 


OOMmMNAAWwWAWANHNNNWNN FE 


The putty shall be of two classes—either whiting putty or white 
lead-whiting putty, as called for in the proposal. 


II. MATERIAL 


No details specified. 
43782°—25 


2 CIRCULAR OF THE BUREAU OF STANDARDS 
III. GENERAL REQUIREMENTS 
No details specified. 
IV. pHa REQUIREMENTS 


1. PIGMENT 


The pigment in whiting putty shall consist of finely powdered 
natural chalk of high-grade quality, with the minimum amount of 
pure tinting colors to produce the desired colors. It shall be free 
from grit, shall be practically neutral, shall possess the property of 
mixing with linseed oil to form good putty, and shall have the 
structure and other physical characteristics of the best natural 
whiting suitable for putty making. The total pigment shall con- 
tain not less than 95 per cent of calcium carbonate. 

The pigment in white lead-whiting putty shall contain not less 
than 10 per cent of white lead (basic carbonate orsbasie sulphate), a 
minimum amount of pure tinting colors if necessary, the remainder 
to be the above-described halewhat whiting. The sum‘ of the whi te 
lead and calcium carbonate in the total pigment. shall be not less 
than 95 per cent. 

' 2, LIQUID 


The liquid in either class shall be entirely pure raw linseed oil. 
3. PUTTY een 


The putty shall be made by thoroughly erin diae” the anne Sides 
of dry pigment with pure raw linseed oil to a doughlike paste of 
proper putty consistency that shall be smooth, uniform, and suitable, 
as received, for glazing purposes. The -putty as-received shall not 
be caked in the container. It shall possess the characteristic prop- 
erties of and shall be equal to the best grade of putty. The color 
when specified shall match a sample mutually aia MBOR by buyer 
and seller. 8 

The putty shall consist of: iat ae ythioat 28 


Ingredients 


Plement nono 2 bad an Resear a eS oe em ae oe ee ee 
rear linseed 0 


eee eet th ok eT ee ee 
eee ee ee ee ee 


Ol ee ee ee ee 


eR EE ERE EE Re 


ee ee es Se ee Ea 


SPECIFICATION FOR PUTTY 3 
V. METHODS FOR SAMPLING AND TESTING 


Deliveries will, in general, be sampled and tested by the follow- 
ng methods, but the purchaser reserves the right to use any addi- 
tional available information to ascertain whether the material meets 
the specification. 

1, SAMPLING 


It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1,000 packages shall be taken as 
representative of the whole. Whenever possible, an original un- 
opened container shall be sent to the laboratory, and when this is 
for any reason not done the inspector shall determine by kneading 
with his hand whether the material has the consistency of good 
putty. He shall then thoroughly mix the contents of the container 
and draw a sample of not less than 1 pound of the thoroughly 
mixed putty, place it in a clean, dry metal or glass container, which 


must be filled with the sample, closed with a tight cover, sealed, 


marked, and sent to the laboratory for test with the inspector’s re- 
port on caking in container. 

When requested, a duplicate sample may be taken from the same 
package and delivered to the seller, and the inspector may take a 
third sample to hold for test in case of dispute. 


z. LABORATORY EXAMINATION 


(a) Cawxinc In Contarner.—When an original package is re- 
ceived in the laboratory, it shall be weighed, opened, and mixed 
with a stiff spatula or paddle. The putty must be no more difficult 
to mix and knead with the hand than a normal good grade of putty. 
The putty shall finally be thoroughly mixed, removed from the con- 
tainer, and the container wiped clean and weighed. This weight 
subtracted from the weight of the original package gives the net 
weight of the contents. A portion of thoroughly mixed putty shall 
be placed in a clean container and the portions for the remaining 


tests promptly weighed out. 


_(b) Moisture anp Orner Vouatite Marrer.—Weigh accurately 
from 8 to 5 g of the putty in a tared flat-bottomed dish about 8 cm 
in diameter, spreading the putty over the bottom. Heat at 105 to 


110° C. for three hours, cool, and weigh. Calculate the loss in 


weight as the percentage of moisture and volatile matter. 

(c) Frnspom From Lumps or Grit.—Spread a portion of the 
mixed putty on a clean piece of glass, noting the presence of any 
lumps. Thin about 5g of the putty with 3 or 4 cc of raw linseed oil 
or turpentine, spread the mixture to thin films on the glass, using a 
wide spatula or putty knife and note the presence of grit. 


4 CIRCULAR OF THE BUREAU OF STANDARDS 


(d) Worxine Quatrrres—Work up about 10 g of the mixed 
putty in the hands, noting its tendency to stick. Apply a portion 
of the putty to the edge of a clean piece of glass, metal, or well- 
filled wood and work it out to a smooth bevel with a spatula or 
putty knife. Spread another portion to very thin films on the glass. 
The putty in both tests shall show good adhesive and elastic prop- 
erties and shall not be “short” or “mealy.” For comparison pur- 
poses a small batch of good putty can be satisfactorily made by tak- 
ing 20 g of dry, fine natural whiting of known quality, adding about 
4 cc of raw linseed oil, and thoroughly kneading to a stiff dough 
by hand. : 

(c) Percentace or Picment.—Weigh accurately about 15 g of 
the putty in a weighed centrifuge tube. Add 20 to 30 cc of “ex- 
traction mixture” (see Reagents), mix thoroughly with a glass rod, 
wash the rod with more of the extraction mixture, and add enough of 
the reagent to make a total of 60 cc in the tube. Place the tube in 
the container of a centrifuge, surround with water, and counterbal- 
ance the container of the opposite arm with a similar tube or a tube 
with water. Whirl at a moderate speed until well settled. Decant 
the clear supernatant liquid, repeat the extraction twice with 40 cc 
of extraction mixture and once with 40 cc of ether. After drawing 
off the ether set the tube in a beaker of water at about 80° C. or on 
top of a warm oven for 10 minutes, then in an oven at 105 to 110° 
C. for two hours. Cool, weigh, and calculate the percentage of pig- 
ment. Grind the pigment to a fine powder, pass through a No. 80 
sieve to remove any skins, and preserve in a stoppered bottle. 

(f) Preparation or Farry Acrps.—To about 25 g of the putty 
in a porcelain casserole add 15 cc of aqueous sodium hydroxide (see 
Reagents) and 75 cc of ethyl alcohol, mix and heat uncovered on a 
‘steam bath until saponification is complete (about one hour). 

Add 100 cc of water, boil, add sulphuric acid of specific gravity 
1.2 (8 to 10 ce in excess), boil, stir, and transfer to a separatory 
funnel to which some water has been previously added. Draw off 
as much as possible of the acid aqueous layer, wash once with water, 
than add 50 cc of water and 50 ce of ether. Shake very gently with 
a whirling action to dissolve the fatty acids in the ether, but not 
so violently as to form an emulsion. Draw off the aqueous layer and 
‘wash the ether layer with one 15 cc portion of water and then 
with 5 cc portions of water until free from sulphuric acid. Then 
draw off the water layer completely. Transfer the ether solution 
to a dry flask and add 25 to 50 g of anhydrous sodium sulphate. 
Stopper the flask and let stand with occasional shaking at a tem- 
perature below 25° ©. until the water is completely removed from 
the ether solution, which will be shown by the solution becoming 
perfectly clear above the solid sodium sulphate. Decant this clear 


SPECIFICATION FOR PUTTY 5 


solution, if necessary, through a dry filter paper into a dry 100 cc 
Erlenmeyer flask. Pass a rapid current of dry air (pass through a 
CaCl, tower) into the mouth of the Erlenmeyer flask and heat to 
a temperature below 75° C. on a dry, hot plate until the ether is 
entirely driven off. 

It is umportant to follow all of the details, since ether generally 
contams alcohol, and after washing with water always contains 
water. It is very difficult to remove water and alcohol by evapora- 
tion from fatiy acids, but the washing of the ether solution and 
subsequent drying with anhydrous sodium sulphate removes both 
water and alcohol. Ether, in the absence of water and alcohol, is 
easily removed from fatty acids by gentle heat. 

The fatty acids prepared as above should be kept in a stoppered 
flask and examined at once. 

(g) Test ror Minerat Om ann Orner UNsaronrri1asLte Mar- 
TER.—Place 10 drops of the fatty acid (f) in a 50 cc test tube, add 
5 ce of alcoholic soda (see Reagents), boil vigorously for five min- 
utes, add 40 cc of water, and mix; a clear solution indicates that 
not more than traces of unsaponifiable matter are present. If the 
solution is not clear, the oil is not pure linseed oil. 

(A) Iopine Nace or Farry Acips.—Place a small quantity of 
the fatty acids (/) in a small weighing burette or beaker. Weigh 
accurately. Transfer by dropping about 0.15 g (0.10 to 0.20 g) 
into a 500 cc bottle having a well-ground glass stopper, or an Erlen- 
meyer flask having a specially flanged neck for the iodine test. 
Reweigh the burette or beaker and determine the amount of sample 
used. Add 10 cc of chloroform. Whirl the bottle to dissolve the 
sample. Add 10 ce of chloroform to two empty bottles like that 
used for the sample. Add to each bottle 25 cc of the Hanus solution 
(see Reagents) and let stand with occasional shaking for one-half 
hour. 

Add 10 ce of the 15 per cent potassium iodide solution and 100 ce 
of water and titrate with standard sodium thiosulphate, using starch 
as an indicator. The titrations on the two blank tests shonld agree 
within 0.1 cc. From the difference between the average of the blank 
titrations and the titration on the sample and the iodine value of 
the thiosulphate solution calculate the iodine number of the sample 
tested. (Iodine number is centigrams of iodine to 1 g of sample.) 
If the iodine number is less than 170, the oil does not meet the 
specification. 

(z) Coarsz Partictes anp Sxrns.—Dry in an oven at 105 to 
110° C. a No. 325 sieve, cool and weigh accurately. Weigh an 
amount of putty containing 10 g of pigment (see V, 2, (e)), add 
100 cc of kerosene, mix thoroughly, and wash with kerosene through 
the sieve, breaking up all the lumps but not grinding. After wash- 


6 CIRCULAR OF THE BUREAU OF STANDARDS 


ing with kerosene until all but the particles too coarse to pass the 
sieve have been washed through wash all kerosene from the sieve 
with ether or petroleum ether, heat the sieve and contents for one 
hour at 105 to 110° C., cool and weigh. | 


3. ANALYSIS OF PIGMENT 


(a) Quatrrative Anatysts.—Make qualitative analysis following 
ordinary methods. 

(b) Reaction anp Frre Arxari.—Boil 2 g of the pigment for 
five minutes with 100 cc of water, filter and to the clear filtrate add 
two drops of phenolphthalein and titrate while hot with 01 N 
hydrochloric acid. Not over 0.2 ce of 0.1 V HCl shall be required 
to destroy the red color. The filtrate shall also be neutral to methyl 
orange indicator. | : | 

(c) Srrvcorurr.—Compare the structure of the pigment under the 
microscope with a known specimen of natural (chalk) whiting (with 
or without the addition of white lead). | . 

(d) Cauctum CarBoNATE (IN THE ABSENCE OF WHITE LEAD) .— 
Weigh accurately 0.25 g of the dry pigment, transfer to a 250 ce 
beaker, moisten with alcohol, dissolve in about 20 ec of 1: 1 hydro- 
chloric acid, keeping the beaker covered. Digest for 10 minutes on 
the steam bath, dilute to about 150 ce, then filter the solution and 
wash the insoluble residue with hot water. Bring to near boiling 
and make alkaline with ammonia after adding a few ce of bromine 
water. Let the precipitate settle, filter, and wash thoroughly with 
hot water. Take the filtrate and washings from the iron, aluminum, 
etc., concentrate to about 200 cc, adding a few drops of ammonia. 
Boil and add while boiling 10 to 15 ce of a hot saturated solution of 
ammonium oxalate, stir, and continue the boiling until the precipi- 
tated calcium oxalate becomes granular. Set on steam bath to settle 
(about one hour). Filter and wash the oxalate thoroughly with 
small amounts of hot water. Transfer the moist precipitate to a 400 
ce beaker by means of a stream of water from the wash bottle, dis- 
solve the part remaining on the filter by washing with warm dilute 
sulphuric acid. Add to the beaker 20 ce of sulphuric acid (1: 1), 
dilute to about 300 cc with hot water, and titrate the oxalic acid 
with 0.1 VY potassium permanganate and report as CaCQ,.* 

=0.0028 g CaO 
1 cc 0.1 V KMnO; = 9 9950 z GaCO,. | 

(ec) Wutre Leap anp Catcrum Carronate.—Weigh accurately 1 ¢ 
of the dry pigment into a 250 cc beaker, moisten with a few drops 
of alcohol, add slowly 25 to 30 e¢ of concentrated hydrochloric acid, 


11f the sample is impure, reference should be made to the methods as given in The 
Analysis of Silicate and Carbonate Rocks, by W. F. Hillebrand, United States Geological 
Survey Bulletin No. 700. ; 


SPECIFICATION FOR PUTTY 1a 


cover, and boil for 5 to 10 minutes. Dilute to about 150 ce with hot 
water and heat for about 15 minutes, let settle on the steam bath, 
filter while hot, and wash any insoluble residue thoroughly with hot 
water. (Avoid allowing the filter paper to become cold.) Make 
the solution just alkaline with ammonia, then just faintly acid to 
litmus, using dilute (1:10) hydrochloric acid. Dilute to about 300 ce 
and pass hydrogen sulphide gas into the clear solution to complete 
precipitation. Settle, filter on paper, and wash with water contain- 
ing some hydrogen sulphide, dissolve the sulphide in hot nitric acid 
(1:3), add 5 to 10 cc of dilute sulphuric acid (1:1), evaporate until 
copious fumes of sulphuric anhydride are evolved, cool, add about 
75 ec of water, and then about 75 cc of 95 per cent ethyl alcohol. 
Stir, let settle, filter on a weighed Gooch crucible, wash with dilute 
alcohol, dry, gently ignite, and weigh as lead sulphate. In the 
absence of sulphates multiply this weight by the factor 0.854 and 
report the result as basic carbonate white lead. In the presence of 
sulphates the weight of lead sulphate multiplied by the factor 0.883 
shall be considered white lead. (It is not possible to determine the 
amount of lead carbonate and lead sulphate when carbonates or sul- 
phates of calcium are present. The arbitrary factor 0.883 is the 
mean of the largest and smallest of the three factors to convert 
PbSO, to (PbCO,),Pb(OH),, to PbSO,PbO, and to (PbSOz),PbO.) 

Boil the filtrate from the sulphide separation to expel hydrogen 
sulphide, add a few drops of nitric acid, and if necessary some ammo- 
nium chloride, make alkaline with ammonia, settle, and filter off 
any precipitate of aluminum, iron, etc., and wash the precipitate 
with hot water. Proceed to determine total calcium as in V, 3, (d), 
and report as calcium carbonate.’ 


4. REAGENTS 


(az) Sranparp Soprom THIOsULPHATE Sorutrion.—Dissolve pure 
sodium thiosulphate in distilled water (that has been well boiled 
to free it from carbon dioxide) in the proportion of 24.83 g of 
erystallized sodium thiosulphate to 1,000 ce of the solution. It is 
best to let this solution stand for about two weeks before standardiz- 
ing. Standardize with pure resublimed iodine.? This solution will 
be approximately decinormal, and it is best to leave it as it is after 
determining its exact iodine value rather than to attempt to adjust 
it to exactly decinormal. Preserve in a stock bottle provided with 


a guard tube filled with soda lime. 


(b) Srarca Sorution.—Stir up 2 to 3 g of potato starch or 5 g 
of soluble starch with 100 cc of 1 per cent salicylic acid solution, 


2See footnote 1, p. 6. 
See Treadwell-Hall, Analytical Chemistry, 2, 6th ed., p. 551. 


8 CIRCULAR OF THE BUREAU OF STANDARDS 


add 300 to 400 cc of boiling water, and boil the mixture until the 
starch is practically dissolved, then dilute to 1 liter. 

(c) Exrraction Mrixrurr.—10 volumes ether (ethyl ether), 6 vol- 
umes benzol, 4 volumes methyl alcohol, 1 volume acetone. 

(d@) Aqurous Soprom Hyproxipe.—Dissolve 100 g of sodium 
hydroxide in distilled water and dilute to 300 ce. 

(¢) Porasstum Iopmwr SoLutrion.—Dissolve 150 g of potassium 
iodide free from iodate in distilled water and dilute to 1,000 ce. 

(f) Hanus Soturion.—Dissolve 13.2 g of iodine in 1,000 cc of 
99.5 per cent glacial acetic acid which will not reduce chromic acid. 
Add enough bromine to double the halogen content determined by 
titration (3 cc of bromine is about the proper amount). The iodine 
may be dissolved by the aid of heat, but the solution should be cold 
when the bromine is added. 

(g) Axuconotic Soprum Hyproxmwwr Sonurion —Dissolve pure 
sodium hydroxide in 95 per cent ethyl alcohol in the proportion of 
about 22 g per 1,000 cc. . Let stand in a stoppered bottle. Decant the 
clear liquid into another bottle and keep well stoppered. This solu- 
tion should be colorless or only slightly yellow when used, and it 
will keep colorless longer if the alcohol is previously treated with 
sodium hydroxide (about 80 g to 1,000 cc), kept at about 50° C. for 
15 days, and then distilled. 

(A) 0.1 NV Porasstum Permancanate Soiurion.—Dissolve 3.161 

g of pure potassium permanganate in a liter of distilled water, let 
_ stand 8 to 14 days, siphon off the clear solution (or filter through an 
asbestos filter), and standardize as follows: In a 400 ce beaker 
dissolve 0.25 to 0.30 g of Bureau of Standards’ sodium oxalate in 
250 cc of hot water (80 to 90° C.) and add 15 ce of dilute sul- 
phuric acid (1:1). Titrate at once with the potassium perman- 
ganate solution, stirring the liquid vigorously and continuously. The 
permanganate must not be added more rapidly than 10 to 15 ce per 
minute, and the last 0.5 to 1 cc must be added dropwise, with par- 
ticular care to allow each drop to be fully decolorized before the 
next is introduced. The solution should not be below 60° C. by the 
time the end point is reached. (More rapid cooling may be pre- 
vented by allowing the beaker to stand on a small asbestos-covered 
hot plate during the titration. The use of a small thermometer as 
a stirring rod is most convenient.) The weight of sodium oxalate 
used multiplied by 0.7469 gives its CaCO, equivalent. 


VI. PACKING AND MARKING 


No details specified. 


SPECIFICATION FOR PUTTY g 
VII. ADDITIONAL INFORMATION 


This specification covers the requirements for a high-grade pre- 
pared putty for general use. It shall be purchased by net weight. 


VIII. GENERAL SPECIFICATIONS 
No details specified. 


) ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D, C. 
AT 
5& CENTS PER COPY 


Me 


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VII. Packing and Re Ot. Sa noe dn ek eee oe ann oe 


U. S. Gov’t 
Master 
Specification 
No. 375 


DEPARTMENT OF COMMERCE 
BUREAU OF STANDARDS 
George K. Burgess, Director 


CIRCULAR OF THE BUREAU OF STANDARDS, No. 302 


[Issued February 9, 1926] 


UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
SHELLAC, FLAKE ORANGE 


FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 375 


This specification was officially promulgated by the Federal Specifications 
Board on January 25, 1926, for the use of the departments and independent 
establishments of the Government in the purchase of shellac, flake orange. 
[The latest date on which the technical requirements of this specification shall become mandatory for all 


departments and independent establishments of the Government is April 26, 1926. They may be put 
into effect, however, at any earlier date, after promulgation.] 


CONTENTS 


Ty wacoeral veguirements) 2) Jou lo ke ie lll UL 
Vo Detail:requirementsxiisc- 2 .- 22s -24-5- in - 2 6ee-4e-ss es 
VI. Methods of sampling and testing------------------------------- 


OOrnwwnds OK Ke 


I. GENERAL SPECIFICATIONS 
There are no general specifications applicable to this specification. 
II. TYPES 


Orange shellac shall be furnished in one of the four types as follows: 
A, B, C, or D. 
Il. MATERIAL 

Orange shellac shall be the manufactured product of stick lac (the 
secretion of the Tacchardia Lacca) freed from most of the lac dye 
and prepared in flake form. Seed, garnet, and button lac are not 
admissible under this specification. 


79613°—26 1 


= CIRCULAR OF THE BUREAU OF STANDARDS 


IV. GENERAL REQUIREMENTS 


Unless specifically waived in the contract, flake orange shellac 
must be “free”; that is, any flakes that may have stuck topetas 
must separate readily under-hand. pressure. 


Fa "? 
“ 
~ 


€ 


V. DETAIL REQUIREMENTS 


Flake orange shellac shall conform to the requirements for the 
respective types given below: 


Color when specified shall be no. darker than a, sample mutually 
agreed upon by the buyer and seller when tested § as per aay VI 


2 (g). 
VI. METHODS OF SAMPLING AND. TESTING ids 


Deliveries will, in general, be sampled and tested by the following 
methods, but the purchaser reserves the right to use any additional avarl- 
able information to ascertain whether the material meets the specification. 

1. Samptrne.—It is mutually agreed by the buyer and seller that 
double handfuls shall be taken from 10 per cent of the packages 
taken at random from the delivery. The composite samples taken 
as above shall be thoroughly mixed, quartered down to approxi- 
mately 3 pounds and divided into bres equal portions which shall 
be separately sealed and marked. The inspector shall send one of 
the sealed samples to the testing laboratory, retam one for umpire 
test in case of dispute, and, if requested, shall deliver the third to the 
seller. 

2. LABoRATORY ExamINaTIoN.—Thoroughly mix the sample of 
shellac to be tested.and grind not less, than a 100 g portion to entirely 
pass a 20-mesh screen and keep in a tightly stoppered container. 
Make the necessary detente aana:t on ae mia with as little 
delay as possible: . : 

(a) Lodine number. sinirodnes 0. 2 “of ‘chee "ticlloa an a 
250 cc dry bottle of clear-glass with a ground-glass stopper, add 20 
cc of glacial acetic acid (see Reagents) and warm the mixture gently 

on top of a hot-water bath until solution. is. complete, (except for the 
wax). A pure shellacis rather difficultly soluble; solution is quicker 
according to the proportion of rosin, present... Add.10 cc of chloro- 
form (see Reagents) and cool the solution to 21.5 to 22.5° C. The 


ee a ee ean SS ee 


a = 


ee a ee ee 


SPECIFICATION FOR FLAKE ORANGE SHELLAC 3 


bottles should be allowed to stand half immersed in‘a shallow pan 
of water, well insulated or equipped with a suitable thermostat, at 
least 30 minutes at 21.5 to 22.5° C. before the Wijs solution nS 
Reagents) is added. Add 20 ce of Wijs solution (which shall be at 
a temperature of 21.5 to 22.5° C.) from a pipette, having a rather 
small delivery aperture (about 30 seconds). Close the bottle, place 
it back into the pan of water, and note the time. The bottles must 
be kept half immersed in water at 21.5 to 22.5° C. during the one 
hour that the shellac is exposed to the Wijs solution. Agitate the 
bottles occasionally during that hour. 

_ Note.—If a number of samples are being run, at least five minutes should be 
allowed between additions of the Wijs solution. 

After exactly one hour add 10 ce of freshly prepared 10 per cent 
potassium iodide water solution (see Reagents), washing into the 
bottle any Wijs solution on the stopper with the same. Titrate the 
solution immediately with the 0.1 N sodium thiosulphate solution 
(see Reagents), allowing the solution to run in slowly (about 25 to 
80 cc) with vigorous shaking until the solution becomes a straw color. 


Now add 15 cc of freshly prepared starch solution (see Reagents) 


and finish titrating. The end point is sharp, as the reaction products 


of shellac remain dissolved in the chloroform; any color Pete 


after one-half minute or so is distegarded. 
- A blank determination shall be run at the same time on the re- 
agents. The blank is necessary on account of the well-known 
effect of temperature changes on the volume and possibly loss of 
strength of the Wijs solution. 
From the volumes of thiosulphate solution required for the sample 
and the blank, respectively, and the iodine value of the thiosulphate 
solution, calculate the iodine number (centigrams of iodine per 
gram of sample) of the shellac. 

The analyst should run in parallel a sample of pure shellac of 


known iodine number as a check upon the reliability of the Wijs 


and thiosulphate solutions. 


(6) Matter insoluble in hot 95 per cent alcohol..—Weigh accurately 
2 g of the sample, transfer to a small beaker and heat the shellac 


with 25 cc of 95 per cent alcohol (see Reagents). Prepare a Gooch 
crucible with an asbestos pad in the customary manner and dry to 


constant weight. Arrange the crucible for filtration by suction and 


pour sufficient boiling alcohol oe it to eevee heat the 
crucible. | 
Nort.—A cold ¢rucible will congeal the wax and hinder filtration. 
Immediately filter the boiling shellac solution, using suction, 
transfer the insoluble matter from the beaker to the crucible, using 


Se I Sd a i a 
1 The continuous extraction method (A. 8. T. M. Standards, 1924, p, 829, Method D 29-24) may be 
used. 


4 CIRCULAR OF THE BUREAU OF STANDARDS 


a “policeman” if necessary and a wash bottle containing hot alcohol. 
Wash the residue in the crucible with boiling alcohol five times, 
nearly filling the crucible each time. C Oe hi 
Norz.—It will be necessary to shut off the suction momentarily to fill the 
crucible. | 
Wash off any film of shellac on the sides or bottom of the crucible 
with hot alcohol and dry to constant weight in an oven at 105 to 
110° C. The weight of the residue in the crucible, multiplied by 
100 and divided by the weight of the sample, is the percentage of 
material insoluble in hot alcohol. acorns Hed 
(c) Moisture and volatile matter—Weigh accurately approximately 
5 g of the sample and heat in a flat-bottomed dish about 4 inches in 
diameter in a well ventilated air bath for three to six hours at 38 to 
43°C. Do not allow the temperature to rise above 43° C.. 
Nore.—With poorly ventilated ovens the drying may take much longer. 
Completeness of drying should be ascertained by continuing the treatment to 
constant weight. Calculate the percentage loss in weight. Ores ae | 
(d) Matter soluble in water—Weigh 10 to 25 g of sample accurately 
and stir thoroughly with 100 ce of distilled water in a suitable sized 
flask or beaker. Cover with a watch glass and allow to stand at room 
temperature (approximately 21° C.) for four hours, stirring occasion- 
ally. Decant the water through a 12.5 cm filter paper into a weighed 
evaporating dish, washing the shellac and paper with at least 50 cc 
more of water. Evaporate the water and dry the extract at 105 to 
110° C. for one hour or more to constant weight. Cool, weigh, and 
calculate the percentage of matter soluble in water. etiette 
(e) Waz.—Dissolve 10 g of the sample in 200 ce of 95 per cent 
alcohol (see Reagents) with agitation at a temperature of 24° C.+ 
3° C. Allow the solution to stand for several hours, preferably 
overnight, in a tall cylindrical vessel maintained at a temperature of 
24° C.+3° C. until the wax has settled to a small layer a tthe bottom 
of the container. Decant the clear solution through a 12.5 em folded 
filter paper, taking care not to disturb the wax layer. Finally, 
transfer the wax to the filter, using 25 cc of alcohol at the prescribed 
temperature. Wash the container and the wax with four 15 cc 
portions of alcohol. The final washings should be colorless. Allow 
most of the alcohol to evaporate from the filter paper and dissolve the 
wax by pouring successive small portions of boiling chloroform. (see 
Reagents) through the paper. Also wash the container with boiling 
chloroform and pour on the filter. _ Collect the filtrate, which should 
contain all the wax, in a tared dish, evaporate the chloroform and dry 
to constant weight at 105 to 110° C. Weigh the wax residue and 
calculate the percentage of wax. Tt: ae ka ‘ais , 
The removal of the wax from the filter paper may also be accom- 
plished in any suitable continuous ‘extraction apparatus. © © 9" 


SPECIFICATION FOR FLAKE ORANGE SHELLAC 5 


_ (f), Ash.—Transfer an accurately weighed portion of from 2 to 3 
g of the sample to a weighed porcelain crucible and ignite at as low 
a temperature as possible until all organic matter has been destroyed. 
Cool, weigh, and calculate the percentage of ash. 

(g) Color—Digest a weighed portion of the sample in a closed 
container with twice its weight of cold 95 per cent alcohol (see Re- 
agents), shaking at intervals until the shellac is entirely “cut.” 
Prepare in the same manner a shellac varnish with exactly the same 
proportion of resin and alcohol, using the sample of shellac mutually 
agreed upon for color by the buyer and seller. Compare the color 
of these two varnishes in clear glass test, tubes of the same diameter. 
The color of the sample under examination shall not be darker than 
that of the sample mutually agreed upon for color by the buyer and 
seller. 

(h) Appearance-—Examine the shellac as received in the labora- 
tory and note whether the material is ‘‘free” or not. If flakes are 
stuck together, ascertain whether hand pressure will separate them 
or not. | | 

3. Reagents.—(a) Acetic acid.—99 per cent acetic acid having a 
melting point of 14.8° C. free from reducing impurities, as shown by 
its action on bichromate-sulphuric acid mixture. 

(b) Wijs solution —Dissolve 13 g of pure iodine (resublimed 
grade) in a liter of acetic acid (see (a) above) using gentle heat if 
necessary. Cool and determine the strength by titration with 
thiosulphate solution (see (d) below). Set aside 50 to 100 cc of the 
solution and introduce dry chlorine gas into the remainder until a 
characteristic color change occurs and the halogen content has 
been doubled. By titration ascertain if the halogen content has 
been more than doubled, and, if so, reduce it by adding a requisite 
quantity of the iodine-acetic acid solution. The final product 
should contain an amount of iodine and chlorine corresponding to 
jodine-monochloride; a slight excess of iodine does no harm, but any 
excess of chlorine over the theory for ICl must be avoided. 

(©) Ohloroform.—U. S. P. chloroform should be used. | 
--(d) Sodium thiosulphate solution.—Dissolve pure sodium thio- 
sulphate in distilled water that has been well boiled to free it from 
carbon dioxide in the proportion so that 24.83 g crystallized sodium 
thiosulphate will be present in 1,000 cc of the solution. It is best 
to let this solution stand for about two weeks before standardizing. 
Standardize with pure resublimed iodine. (See Analytical Chemistry, 
Treadwell-Hall, vol. II, 3d ed., p. 646.) This solution will be 
approximately decinormal, and it is best to leave it as it is after 
determining its exact iodine value, rather than to attempt to adjust 
it to exactly decinormal strength. Preserve in a stock bottle pro- 
vided with a guard tube filled with soda lime. 


6 CIRCULAR OF THE BUREAU OF STANDARDS 


(e) Starch solution.—Dissolve 0.2 g of starch per 100° ce of aie 
tilled water and boil. 

(f) Potassium iodide solution.—Dissolve potassium iodide free torn 
iodate in distilled water in the proportion of 1 part salt to 10 parts 
of solution. 

(g) Ninety-five per cent alcohol.—Hither 95 per cent ethyl alcohol 
or 95 per cent specially denatured alcohol, U. S. Internal Revenue 
Bureau Formula No. 1 or No. 30. (Formula No. 1 calls for the 
addition to 100 gallons ethyl alcohol (190 proof) of 5 gallons of 
approved wood alcohol, the wood alcohol to be subject to the same 
specifications as are imposed upon wood alcohol used in completely 
denatured alcohol.) (Formula No. 30 calls for the addition to 100 
gallons of pure ethyl alcohol of 190 proof of 10 gallons of pure methyl 
alcohol, which methyl] alcohol is to have a fi gravity of not 
more than 0.810 at 60° F.) 


VII. PACKING AND MARKING 4 


There are no packing and marking requirements Sppene ura to 0 thi 


specification. 
VIII. NOTES 


This specification covers the requirements for orange flake shellac 
for use in ship bottom paints and in the preparation of orange shellac 
varnish. In general, type A will include the grades of shellac known 
in the trade as ‘Double triangle G,” “Diamond I,” SR RORL ! 
and the highest grades ‘‘D. C.’”’ and ey, S..0.” 

In general, type B will include the grades considered in the ae 
as lower than ‘‘superfine,”’ but beer than ‘‘pure T. N.,” such as 
“fine,” ‘good,’’ and “heart.” , 

Bene C represents the grade aawail in the pay as pate T.. N? ” 
This material is rosin free, but is darker and contains more insoluble 
material than types A or B. | 

Type D represents the grade known in the as “U. Ss. Ss. “ 
T. N.” It usually contains rosin up to a maximum of 3 per cent, 
and, in addition, it is generally darker and contains more insoluble 
material than types A or B, but is usually a little idle in. color 
than type C. tudiaints 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM rN 
THE SUPERINTENDENT OF DOCUMENTS JM POA DRS 
GOVERNMENT PRINTING OFFICE 
beret rab D. C. 


5 CENTS PRE COPY ook Bi Stee 
Vv ry er : ™ os 


—_. aa: | eh es ee 


U. S. Gov’t 
Master 
Specification 
No. 376 


DEPARTMENT OF COMMERCE 
BUREAU OF STANDARDS 
George K. Burgess, Director 


CIRCULAR OF THE BUREAU OF STANDARDS, No. 303 


[Issued February 9, 1926] 


UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
VARNISH, SHELLAC 


FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 376 


This specification was afiicially promulgated by the Federal Specifications 
Board on January 25, 1926, for the use of the departments and independent 
establishments of the Government in the purchase of varnish, shellac. 


- [The latest date on which the technical requirements of this specification shall become mandatory for all 


departments and independent establishments of the Government is April 26, 1926. They may be put 
into effect, however, at any earlier date, after promulgation.] 


CONTENTS 


VI. Methods of sampling and testing__.--___-2__=- apn Pepe psp apes yep: TONS 
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3 I, GENERAL, SPECIFICATIONS 
' There are no general specifications applicable to this specification. 
: | I. TYPES 


‘ Shellac varnish shall be furnished as “Orange,” type 1 or 2, and 
as “Bleached,” type 1 or 2. Each type shall be furnished as Tere 
medium, or heavy body, as specified in the contract. 


Ill. MATERIAL 


Shellac varnish shall be made by “cutting” the specified type of 
shellac, the manufactured product of stick lac (the secretion of the 
Tacchardia Lacca) in 95 per cent specially denatured alcohol, formula 
No. 1 of the United States Internal Revenue Bureau. 

: 79614°—26t | 1 


2 CIRCULAR OF THE BUREAU OF STANDARDS 
IV. GENERAL REQUIREMENTS 
Therevare no general requirements applicable to this specification. 


V., DETAIL REQUIREMENTS «5 4 


The nonvolatile matter in ‘shellac varnish shall conform to the 
requirements as given below for the respective types: 


Iodine number (maximum) - ........-----7----2-------------<-- 

Matter insoluble in hot 95 per cent alcohol (maximum) per cent. 

— (martini) 2205 os Ss eee eer ae emma G0. s0= 
Aah (maxtmuin) us ops s ose use ac sean Span be ceeeeened Gos. 


Color, when erection shall be no jae than a sample of shellac 
varnish mutually agreed upon by the buyer and seller. 

The body of the respective types of varnish shall be based, es 
the percentage of nonvolatile matter determined as in Aeghion, Mie 
2—(a): bite Bheamehukgp 


Minimum allowable percentage of nonvolatile matter: ia 
Light body varnish. o>. .0s..0 2.222 s2eie a oo nee cnesbe se een nena an ee 
Medium-body ‘varnish. 2 ~ 22.2 2220 22 ee ec annus ethene 
Heavy body varnish... 5.3 oo 5<ssa<sarcancscuann anesee see wr eens nee 


VI. METHODS OF SAMPLING AND TESTING 


Deliveries will, in general, be sampled and tested by the following 
methods, but the purchaser reserves the right to use any additional 
information to ascertain whether the materval meets the specification. 

1. Samprine.—It is mutually agreed by, buyer and _seller,that a 
single package out of each lot of not more than 1,000 packages be 
taken as representative of the whole. ..Whenever possible an original 
unopened container shall be sent to the laboratory, and when for any 
reason this is not done the inspector shall thoroughly mix the contents 
of the container sampled, transfer not less than. 1 quart to a clean dry, 
glass bottle, which must be nearly filled with the sample, securely 
stoppered with a new clean cork or well-fitting cover or cap, sealed 
and distinctly labeled by the inspector. The inspector should take 
a duplicate from the container sampled, to be held for check in case 
of dispute, and when requested should take a sample for the seller. _ 

2. LABORATORY EXAMINATION.— (a) Nonvolatile matter. Place’ a 
portion of the thoroughly mixed ee, in a stoppered bottle or A 


“SPECIFICATION FOR SHELLAC VARNISH 3 


ing pipette... Weigh the container and sample. - Transfer 1.25 g (40.25 
g) of the sample to a weighed flat-bottomed metal dish about 8 cm-in 
diameter (a friction-top can plug). Weigh the container again and 
by difference calculate the exact weight of the portion transferred to 
the weighed dish. Heat the dish and its contents in an oven main- 
tained at 105 to 110° C. for three hours, cool, and weigh. From the 
weight of the residue left in the dish and the weight of the sample 
taken calculate the percentage of nonvolatile residues 

(b) Iodine number of the nonvolatile residue.—Transfer 1.5 cc of the 
shellac varnish by means of a pipette to a flat-bottomed glass or por- 
celain dish at least 8 cm in diameter. Add 1 to 2 cc of 95 per cent 
alcohol. to spread the varnish evenly over the bottom of the dish. 
Heat the dish and contents at 85 to 90° C. for one-half hour. Scrape 
the residue from the dish and place 0.2 g in a 250 ce dry bottle of 
clear glass with a ground-glass stopper, add 20 cc of glacial acetic 
acid (see Reagents), and warm the mixture gently on top of a hot- 
water bath until solution is complete (except for the wax). A pure 


‘shellac is rather difficultly soluble; solution is quicker according to 
‘the proportion of rosin present. Add 10 cc of chloroform (see Re- 


agents), and cool the solution to 21.5 to 22.5° C. The bottles should 
be allowed to stand half immersed in a shallow pan of water, well 


’ insulated or equipped with a suitable thermostat, at least 30 min- 


utes at 21.5 to 22.5° C. before the Wijs solution (see Reagents) is 
added. Add 20 cc of Wijs solution, (which shall be at a temperature 
of 21.5 to 22.5° C.) from a pipette, having a rather small delivery 
aperture (about 30 seconds). Close the bottle, place it back into the 
pan of water, and note the time. The bottles must be kept half im- 
mersed in water at 21.5 to 22.5° C. during the one hour that the shellac 
is exposed to the Wijs solution. Agitate the bottles ancasiopally 
during that hour. 

_Nors.—If a number of samples are being run, at least five minutes should 
be allowed between the additions of the Wijs solution. 


After exactly one hour add 10 cc of freshly prepared 10 per cent 


potassium iodide water solution (see Reagents), washing into the 


bottle any Wijs solution on the stopper with the same. Titrate the 
solution immediately with the 0.1 N sodium thiosulphate solution 
(see Reagents), allowing the solution to run in slowly (about 25 to 
30 cc), with vigorous shaking until the solution becomes a straw 
color. Now-add 15 cc of freshly prepared starch solution (see Re- 
agents) and finish titrating. The end point is sharp, as the reaction 
products of shellac remain dissolved in the chloroform; any color re- 
turning after one-half minute or so is disregarded. 


1 The method described in Tentative Methods of Testing Shellac Varnish, published by the A. S. T. M. 
in 1925 may be followed, but the calculation shall be based on solids determined without any allowance for 
an assumed moisture content in the shellac, since this has been allowed for in the specification. 


4 CIRCULAR OF THE BUREAU OF STANDARDS 


A blank determination shall be run at the same time on the re- 
agents. The blank is necessary on account of the well-known effect 
of temperature changes on the volume and possibly loss of fret 
of the Wijs solution. 

From the volumes of thiosulphate solution required for the 
sample and the blank, respectively, and the iodine value of the 
thiosulphate solution, Galoalatd the iodine number PCR of 
iodine per gram of sample) of the shellac. 

The analyst should run in parallel a sample of cis shellac of 
known iodine number as a check upon the reliability of the Wijs and 
thiosulphate solutions. 

(c) Material insoluble in hot 95 per cent aleohols 2.::/Rhiofodghly 
shake the sample and at once place a portion of the well-mixed sam- 
ple in a stoppered bottle or weighing pipette. Weigh the contaier 
and sample, thoroughly mix by shaking, and transfer approximately 
5 cc of the sample to a small beaker. Weigh the container again and 
by difference calculate the exact weight of the portion transferred 
to the beaker. Heat the shellac varnish in the beaker with 25 ec 
of 95 per cent alcohol (see Reagents). Prepare a Gooch crucible 
with an asbestos pad in the customary manner and dry to constant 
weight. Arrange the crucible for filtration by suction and pour 
sufficient boiling alcohol through it to heat thoroughly the crucible. ° 

Nors.—A cold crucible will congeal the wax and hinder filtration. 

Immediately filter the boiling shellac solution, using suction, 
transfer the insoluble matter from the beaker to the crucible, using 
a “policeman” if necessary and a wash bottle containing hot alcohol. 
Wash the residue in the crucible with boiling alcohol: are — 
nearly filling the crucible each time. | 

Nore.—It will be necessary to shut off the suction Gre ag eign 2 to me the 
crucible. 

Wash off any film of shellac on the sides or bottom ss the tae 
with hot alcohol and ‘dry to constant weight in an oven at 105 to 
110° C. The weight of the residue in the crucible multiplied | by 
100 and divided by “the weight of the nonvolatile matter in the sample 
taken is the percentage of Tatetial insoluble in hot alcohol. 

(d) Waxz.—Thoroughly mix the sample and at once transfer a 
weighed portion of approximately 30 g to a tall cylindrical vessel. 
Dilute the varnish with 180 ec of 95 per cent alcohol (see Reagents) at 
a temperature of 24° 0.+3° ©. and thoroughly mix. Allow the 
solution to stand for several hours, preferably overnight in a tall cylin- 
drical vessel maintained at a temperature of 24° C.+3° C. until the 
a a 


2“'The continuous extraction method” (A. 8. T. M, Standards, 1924, p. mass Method Assisi may also 
be used, . 


SPECIFICATION FOR SHELLAC, VARNISH 5 


wax has settled to a small layer at the bottom of the container. 
Decant the clear solution through a 12.5 cm folded filter paper, taking 
care not to disturb the wax layer. Finally, transfer the wax to the 
filter, using 25 cc of alcohol at the prescribed temperature. Wash 
the container and the wax with rour 15 cc portions of alcohol. The 
final washings should be colorless. Allow most of the alcohol to 
evaporate from the filter paper and dissolve the wax by pouring suc- 
cessive small portions of boiling chloroform (see Reagents) through 
the paper. Also wash the container with boiling chloroform and 
pour on the filter. Collect the filtrate, which should contain all 
the wax, in a tared dish, evaporate the chloroform and dry to con- 
stant weight at 105 to i10° C. Weigh the wax residue and calculate 
the percentage of wax based on the weight of nonvolatile residue in the 
sample of shellac varnish taken. 

The removal of the wax.from the filter paper may also be accom- 
plished in any suitable continuous extraction apparatus. 

(e) Ash.—Transfer an accurately weighed portion of 5 to 6 g of 
the sample to a weighed porcelain crucible and evaporate most of 
the alcohol on the steam bath. Ignite at as low a temperature as 
possible until all organic matter has been destroyed. Cool, weigh, 
and calculate the percentage of ash based upon the weight of non- 
volatile material in the sample of varnish taken. 

(f) Color.—Compare the color of the sample under examination 

with the color of the sample mutually agreed upon for color by the 
buyer and seller in clear glass test tubes of the same diameter. 

_ The color of the sample under examination shall not be darker 
than the color of the sample mutually agreed upon for color by the 
buyer and seller. 

Notse.—The sample used for color comparison should be kept in a glass con- 
tainer in a dark place. 

3. Reacents.—(a) Acetic acid.—Ninety-nine per cent acetic acid 
having a melting point of 14.8° C., free from reducing impurities as 
shown by its action on bichromate-sulphuric acid mixture. 

(b) Wajs solution.—Dissolve 13 g of pure iodine (resublimed grade) 
_in a liter of acetic acid (see (a) above), using gentle heat if necessary. 
Cool and determine the strength by titration with thiosulphate solu- 
tion (see (d) below). Set aside 50 to 100 ce of the solution and intro- 
duce dry chlorine gas into the remainder until a characteristic color 
change occurs and the halogen content has been doubled. By titra- 
tion ascertain if the halogen content has been more than doubled, 
‘and, if soy reduce it by adding a requisite quantity of the iodine- 
acetic atid solution. The final product should contain an amount of 
iodine and chlorine corresponding to iodine-monochloride; a slight 
excess of iodine does no harm, but any excess of chlorine over the 
theory for ICl must be avoided. 


6 CIRCULAR OF THE BUREAU OF STANDARDS 


(c) Chloroform.—U. Sv P. chloroform should be used.” bore 
meee: “thiowl 
phate in distilled ae that has ween well boiled to free it from 
carbon dioxide in the proportion so that 24.83 g crystallized sodium 
thiosulphate will be present in 1,000 ce of the solution. “It is best to 
let this solution stand for about two weeks before standardizing. 
Standardize with pure resublimed iodine. (See Analytical Chemis- 
try, Treadwell-Hall, Vol. II, 3d ed., p. 646.) This solution ‘will be 
approximately decinormal, and it is best to leave it as it-is after deter- 


mining its exact iodine value, rather than to attempt to adjust it to 


exactly decinormal strength. Preserve in a stock bottle provided 
with a guard tube filled with soda lime. 

(e) Starch solution.—Dissolve 0.2 g of starch per 100 cc of distilled 
water and boil. 

(f) Potassium iodide solution.— Dissolve potassium iodide free from 
iodate in distilled water in the proportion of 1 part salt to 10 parts 
of solution. 

(g) Ninety-five per cent alcohol.—Either 95 per cent ne Alcohol 
or 95 per cent specially denatured alcohol, United States Internal 
Revenue Bureau Formula No. 1 or No. 30. (Formula No. 1 calls for 
the addition to 100 gallons ethyl alcohol (190 proof) of 5 gallons ap- 
proved wood alcohol, the wood alcohol to be subject: to the same 
specifications as are imposed upon wood alcohol used in ‘eompletely 
denatured alcohol. | Formula No. 30 calls for the addition to 100 gal- 
lons ethyl alechol of 190 proof of 10 gallons of pure methyl alcohol, 
which methyl alcohol is to have a specific gravity of not more than 
0.810 at 60° F.) 


VIl. PACKING AND MARKING 


Shellac varnish shall be shipped in containers that. will not darken 
the product during storage. 


VIIt. NOTES 


This specification is intended to cover all the needs of the Govern- 
- ment for shellac varnish, both orange and bleached. Bleached shel- 
lac varnish is sometimes known as white shellac varnish. In‘general, 
type 1 of orange shellac varnish will include the rosin-free material 
and the lighter colored varnishes, while type 2 is intended for use 
where the presence of small percentages of rosin (not over 3 per cent) 
is not objectionable and where lightness of color is not an pega: 
factor. 

In general, type 1 of bleached shellac varnish will fulfill all the 
needs for a white shellac varnish. Type 2 will be used only im cases 


SPECIFICATION FOR SHELLAC VARNISH fi 


where a clear bleached varnish (practically free from wax or other 
suspended matter) is necessary. 
Light, medium, and heavy body varnishes correspond to 3.5, 4.0, 
and 4.5 pound ‘“‘cuts” of shellac, respectively. The minimum 
| allowable percentages of nonvolatile matter for each body of varnish 
given in Section V of this specification have been corrected for maxi- 
mum moisture and volatile matter in flake orange shellac of 2 per 
cent and in bleached dry shellac of 5 per cent, so that varnishes 
made by cutting 3.5, 4.0, and 4.5 pounds of either orange or bleached 
shellac in 1 gallon of specially denatured alcohol should meet the 
nonvolatile requirements of Section V. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT 


5 CENTS PER COPY 
4 


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OO 


U. S. Gov’t 
Master 
Specification 


No. 475a 


DEPARTMENT OF COMMERCE 
BUREAU OF STANDARDS 


George K. Burgess. Director 


CIRCULAR OF THE BUREAU OF STANDARDS, No. 330 


{Issued April 28, 1927] 


UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
OIL, LINSEED, BOILED ' 


FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 475a 
[Revised March 5, 1927] 


This specification was officially promulgated by the Federal Specifications 
Board on February 3, 1922, for the use of the departments and independent 
establishments of the Government in the purchase of boiled linseed oil. 


[The latest date on which the technical requirements of this revision of this specification shall become 
mandatory for all departments and independent establishments of the Government, is June 6, 1927. They 
may be put into effect, however, at any earlier date.] 


CONTENTS 


Be eeetrernerinl Sir Wor kitianahin.$ — ois eA ong an pene 
LST RSS a5 a gg gm 
S wetesanemed viromon testis be ke Ll Sotel Siled A eyo tli 
VI. Methods of sampling, testing, and basis of purchase_____________-_ 
ee RMN = ei ig ee. Let en Bk ee a ee 

I Rg ine ce ee Rr ae de eo tT oe pe 
ENE OES IIE Sarat alecapiaetiegs Dy. Dayne ee SNES MCE 

EP PE TESCO an oe lo es ee ln 
Une OM MNTTents. ee tee eee 
VIII. Notes___.--_-- es PORES SiS. SPS s28 tS ee ay SOY Sass 


Go 0. ~1'@ ks WR hok> Rt 


1 For raw linseed oil see United States Government master specification for raw linseed oil, Federal 
Specifications Board specification No. 4a (Bureau of Standards Circular No. 82, 3d ed.). This specifica- 
tion (F. 8. B. specification No. 475a) supersedes that part of F. 8. B. specification No. 4, which covered 
boiled linseed oil, 


43232°—27 


2 CIRCULAR OF THE BUREAU OF STANDARDS 
I. GENERAL SPECIFICATIONS 
There are no general specifications applicable to this specification. 
Il. TYPES 


A. Kettle-boiled linseed oil. 
B. Quick process boiled linseed oil. 


Ill. MATERIAL AND WORKMANSHIP 
See detail requirements. 
IV. GENERAL REQUIREMENTS 
See detail requirements. | 
V. DETAIL REQUIREMENTS 


Boiled linseed oil shall be pure linseed oil that has been treated 
(preferably by heating—kettle boiled) with compounds of lead, and 
at the option of the manufacturer with suitable compounds of other 
drying metals, so as to produce a product that will dry rapidly. It 
shall be clear, free from sediment, and shall meet the following 
requirements: 


Maximum | Minimum 


Time of drying on glass.......-~--.--<-.~.. 5st dees Geta aee © eee Seem JU hours... 180 TN nteteenoole 
Loss on’heating at 105 to 110°. O.. .250- 5.35 ence ancicee poneeceeuseweuse per cent.- Fe tg Baty co aussi ie 
Specific gravity at 15.5/15.5° C_-_-.-..----------------------- eo on nnn een nennnn . 945 10, 937 
Reid num bor: on oo needs boda dacaconnsn ce aeicassareeseeeunee yee eee e aaa 7.8 i eee 
Saponification number-_.---.----.--------------------------4ne0- nen +e Soe ses sneer 195.0 189.0 
Unsaponifiable matter... ...2 2. -s20<-- cence ne cen wn enenonsresacenneesas per cent_. 1500 cones cee se 
Todine number... ockonceew wen oka oe eh ewe ich ole u~ tak a teee ewe eee sews Ws. s] weaconsee tee 168. 0 
se ep wbucusbecbewdlwena cede adea scone ea cewae seared paten sete Marrero per cent. » DD Hedin deta 
Thond eon wet oes ae ee ea i eae nde ee eee ee GO0icuoleedtaaesueee 05 


ht quick process, not kettle boiled, oil is called for in contract, the minimum specific gravity shall 
9300. - 


VI. METHODS OF SAMPLING, TESTING, AND BASIS OF 
PURCHASE , 


Deliveries will, in general, be sampled and tested by the following 
methods, but the purchaser reserves the right to .use any additional 
available information to ascertain whether the material meets the speci- 
fication. ik aba 

1. SAMPLING 


The method of sampling given under (a), below, should be used 
whenever it is feasible to apply it. To meet conditions when (@) is 
not applicable, method (6), (c), or (d) is to be used, according to the 
special conditions that obtain. | 


ae ee Ss ee 


ai peat al 


SPECIFICATION FOR BOILED LINSEED OIL 3 


(a) Durine Loapine or TanK Cars or FILLING oF CONTAINERS 
FOR SHIPMENT AT THE Factrory.—The purchaser’s inspector shall 
draw a sample at the discharge pipe where it enters the receiving 
vessel or vessels. The total sample shall be not less than 5 gallons 
and shall be a composite of small samples of not more than 1 pint, 
each taken at regular intervals during the entire period of loading or 
filling. | 

The sample thus obtained shall be thoroughly mixed, and fro 
this composite sample three portions of not less than 1 quart each 
shall be placed im clean, dry glass bottles or tin cans which must be 
filled with the sample and securely stoppered with new clean corks 
or well fitting metal covers or caps. These shall be sealed and labeled 
distinctly by the inspector, and one delivered to the buyer, one to the 
seller, and the third held for check in case of dispute. 

(6) From Loapgep Tank Cars or OTHER LarcEe Vessets.—The 
total sample shall be not less than 5 gallons and shall be a composite 
of numerous small samples of not more than 1 pint each, taken from 
the top, bottom, and intermediate points by means of a glass or metal 
container with removable stopper or top. This device attached to a 
suitable pole is lowered to the various desired depths when the 
stopper or top is removed and the container allowed to fill. The 
sample thus obtained is handled as in (@). 

(c) Barrets AND Drums.—Not less than 5 per cent of the packages 
in any shipment or delivery of barrels and drums shall be sampled. 
The packages shall be shaken, rolled, and stirred to mix the contents 
thoroughly. The samples from the individual containers shall be 
taken through the bung hole or holes not less than 114 inches in 
diameter, bored in the head or side for the purpose. The apparatus 
for drawing the sample shall consist of a glass tube about 1 inch in 
diameter and somewhat longer than the length or diameter of the oil 
container, a conical stopper that will fit the glass tube and is not more 
than one-half inch long fastened to a stiff metal rod not more than one- 


fourth inch in diameter and not less than 4 inches longer than the 


glass tube. The stopper is lowered by the rod until it rests on the 
bottom of the cask, the tube slipped down slowly over the rod, and 
finally pressed on the stopper. By holding tube and rod the column 
of oil can then be removed. This process is repeated until the re- 
quired amount of sample is obtained, which must not be less than 2 
gallons This is mixed and handled as in (q). 

(2) Smati Conrarners, Cans, Erc., of 10 GatLons or Less.— 
Small containers, cans, etc., of 10 gallons or less should be sampled 
while filling by method (a) whenever possible. When method (a) 
is not applicable, it is mutually agreed that: In all cases the total 
sample taken shall not be less than 3 quarts. This shall be obtained 
by taking at least 1 package from each lot of not more than 300 


4. CIRCULAR OF THE BUREAU OF STANDARDS 


packages. The sample thus taken shall be thoroughiy mixed and 
subdivided as in (a). 
2. TESTING 


All tests shall be made on oil that has been thoroughly agitated 
before removal of a portion for analysis. 

(a) Time or Dryine on Guass.—Flow the oil over a perfectly 
‘hn glass plate. Place plate in a nearly vertical position im air 
that is between 15 and 35° C. and of humidity between 48 and 60 
per cent saturation. After about two hours test the film at intervals 
with the finger at points not less than 214% cm from the edges. The 
film will be considered dry when it no longer adheres to the finger 
and does not rub up appreciably when the finger is lightly rubbed 
across the surface. 

(6) Sprciric Graviry.—Determine at 15.5/15.5° C. by any con- 
venient method that is accurate within two points in the fourth 
decimal place. 

(c) Acrpy Numper.—Weigh from 5 to 10 g of the oil. Transfer 
to a 300 cc Erlenmeyer fiask. Add 50 cc of a mixture of equal parts 
by volume of 95 per cent ethyl alcohol and c. p. reagent benzol. 
(This mixture should previously be titrated to a very faint pink 
with dilute alkali solution, using phenolphthalein as an indicator.) 
Add phenolphthalein indicator and titrate at once to a faint perma- 
nent pink color with standard sodium or potassium hydroxide solu- 
tion. Calculate the acid number (milligrams KOH) per gram of oil. 

(d) SAPONIFICATION NumBER.—Weigh about 2 ¢ of the oil and 
transfer to a 300 cc Erlenmeyer flask. Add 25 ce of alcoholic sodium 
hydroxide or potassium hydroxide solution. Put a condenser loop 
inside the neck of flask and heat on the steam bath for one hour. 
Cool, add phenolphthalein as indicator, and titrate with 0.5 N 
H.SO,. Run two blanks with the alcoholic alkali solution. ‘These 
should check within 0.1 cc of 0.5 N H,SO,. From the difference 
between the number of cubic centimeters of 0.5 N H,SO, required 
for the blank and for the determination, calculate the sapere 
number (milligrams KOH required for 1 g of the oil). 

(ec) UNSAPONIFIABLE Matrer.—Weight 8 to 10 g of the oil and 
transfer to a 250 cc long neck flask. Add 5 ce of a concentrated | 
solution of sodium hydroxide (equal weights of NaOH and H;O) and 
50 ce of 95 per cent ethyl alcohol. Put a condenser loop inside 
the neck of the flask and boil for two hours. Occasionally agitate 
the flask to break up the liquid, but do not project the liquid onto 
the sides of the flask. At the end of two hours, remove the con- 
denser and allow the liquid to boil down to about 25 cc. 

Transfer to a 500 cc glass-stoppered separatory funnel, rinsing 
with water. Dilute with water to 250 cc, add 100 ce of redistilled 
ether. Stopper and shake for one minute. Let stand until the 


SPECIFICATION FOR BOILED LINSEED OIL 5 


two layers separate sharp and clear. Draw all but one or two 
drops of the aqueous layer into a second 500 cc separatory funnel 
and repeat the process using 60 cc of ether. After thorough sepa- 
ration, draw off the aqueous solution into a 400 cc beaker, then the 
ether solution into the first separatory funnel, rinsing down with 
a little water. Return the aqueous solution to the second separa- 
tory funnel and shake out again with 60 cc of ether in a similar 
manner, finally drawing the aqueous solution into the beaker and 
rinsing the ether into the first separatory funnel. 

Shake the combined ether solution with the combined water 
rinsings and let the layers separate sharp and clear. Draw off the 
water and add it to the main aqueous solution. Shake the ether 
solution with two portions of water (about 25 cc each). Add these 
to the main water solution. 

Swirl the separatory funnel so as to bring the last drops of water 
down to the stopcock and draw off until the ether solution just fills 
the bore of the stopcock. Wipe out the stem of the separatory 
funnel with a bit of cotton on a wire. Draw the ether solution 
(portion wise if necessary) into a 250 cc flask and distill off. While 
still hot, drain the flask into a small weighed beaker, rinsing with a 
little ether. Evaporate this ether, cool the beaker, and weigh. 
(The unsaponifiable oil from adulterated drying oils may be volatile 
and as a consequence may evaporate on long heating. Therefore, 
heat the beaker on a warm plate, occasionally blowing out with a 
current of dry air. Discontinue heating as soon as the odor of ether 
is gone.) 

(f) loptns Numsper.—Place a small quantity of the sample in a 
small weighing burette or beaker. Weigh accurately. Transfer by 
dropping from 0.09 to 0.15 g of oi to a 500 cc bottle, having a 
well-ground glass stopper, or an Erlenmeyer flask, having a specially 
flanged neck for the iodine tests. Reweigh the burette or beaker 
and determine the amount of sample used. Add 10 cc of chloro- 
form. Whirl the bottle to dissolve the sample. Add 10 cc of 
chloroform to each of two empty bottles or flasks like that used for 
the sample. Add to each bottle 25 cc of the Wijs solution and let 
‘stand with occasional shaking for one hour in a dark place at a tem- 
perature of from 21 to 23°C. Add 10 cc of the 15 per cent potassium 
iodide solution and 100 cc of water. Titrate with 0.1 N sodium 
thiosulphate, using starch as an indicator. The titrations on the 
two blank tests should agree within 0.1 cc. From the difference 
between the average of the blank titrations and the titration on the 
samples and the iodine value of the thiosulphate solution calculate 
the iodine number of the samples tested. (lodine number is given in 
centigrams of iodine to 1 g of sample.) 


6 CIRCULAR OF THE BUREAU OF STANDARDS 


(g) Loss on Heatine at 105 to 110° C.—Place 10 g of the oil in 
an accurately weighed 50-cc Erlenmeyer flask and weigh. Heat in 
an oven at a temperature between 105 and 110° C. for 30 minutes, 
then cool and weigh. Calculate the percentage loss. This deter- 
mination shall be made in a current of carbon dioxide. 

(hk) Asu.—Tare a porcelain crucible or dish. Add 10 to 25 ce of 
oil, carefully weighing the amount added. Place on a stone slab on 
the floor of a hood. Ignite by playing the flame of a burner on the 
surface of the oil and allow to burn quietly until most of the oil is 
burned off; then transfer to a muffle or over a flame and continue 
heating at a low temperature (not over a dull red) until all carbona- 
ceous matter is consumed. Cool, weigh, and compute the percentage 
of ash. 

(1) Leap.—Dissolve the ash (h) in dilute nitric acid to which 
a little hydrogen peroxide has been added and determine lead by the 
sulphate or any other equally accurate method. 

(7) ApPEARANCE.—Transfer a portion of the sample to a clear glass 
tube and note appearance. 

3. REAGENTS 


(2) SraNDARD Sopium HyproxipE SoLuTION. —Prepare a stock 
concentrated solution of sodium hydroxide by dissolving sodium 
hydroxide in water in the proportion of 200 g NaOH to 200 cc water. 
Allow this solution to cool and settle in a stoppered bottle for several 
days. Decant the clear liquid from the precipitate of sodium car- 
bonate into another clean bottle. Add clear barium hydroxide 
solution until no further precipitate forms. Again allow to settle 
until clear. Draw off about 175 cc and dilute to 10 liters with freshly 
boiled distilled water. Preserve in a stock bottle provided with 
a large guard tube filled with sodalime. Determine the exact strength 
by titrating against pure benzoic acid (CsH;COOH), using phenol- 
phthalein as indicator. (See Bureau of Standards Scientific Paper No. 
183.) This solution will be approximately one-fourth normal, but 
do not attempt to adjust it to any exact value. Determine its exact 
strength and make proper corrections in using it. 

(6) Auconotic Soprum Hyproxipr Soiution.—Dissolve pure 
sodium hydroxide in pure 95 per cent ethyl alcohol im the propor- 
tion of about 22 g per 1,000 cc. Let stand in a stoppered bottle, 
decant the clear liquid mis another bottle, and keep well stoppered. 
This solution should be colorless or only slightly yellow when used. — 

(c) Stanparp Sopium TxHtosuLtpHaTe SoLtution.—Dissolve pure 
sodium thiosulphate in distilled water that has been well boiled to 
free it from carbon dioxide in the proportion so that 24.83 ¢ crystal- 
lized sodium thiosulphate will be present in 1,000 ec of the solution. 
It is best to let this solution stand for about two weeks before stand- 


~ 


SPECIFICATION FOR BOILED LINSEED OIL "4 


ardizing. Standardize with pure resublimed iodine. (See Analyti- 
cal Chemistry, Treadwell-Hall, vol. 2, 6th ed., p. 551.) This solu- 
tion will be approximately decinormal, and it is best to leave it as 
it is after determining its exact iodine value, rather than to attempt 
to adjust it to exactly decinormal strength. Preserve in a stock 
bottle provided with a guard tube filled with soda lime. 

(dq) Srarcu SoLuTion.—Stir up 2 or 3 g of potato starch or 5 g 
soluble starch with 100 cc of 1 per cent salicylic acid solution, add 
300 to 400 cc boiling water, and boil the mixture until the starch 
appears to be dissolved. Dilute to 1 liter. 

(e) Porasstum lopipr Sontution.—Dissolve 150 g of potassium 
iodide free from iodate in distilled water and dilute to 1,000 cc. 

(f) Wiss Sotution.—The preparation of the iodine monochloride 
solution presents no great difficulty, but it should be done with care 
and accuracy in order to obtain satisfactory results. There shall be 
in the solution no sensible excess either of iodine or more particularly 
of chlorine over that required to form the monochloride. This con- 
dition is most satisfactorily attained by dissolving in the whole of the 
acetic acid to be used the requisite quantity of iodine, using a gentle 
heat to assist the solution, if it is found necessary. Dissolve iodine 
in glacial acetic acid that has a melting point of 14.7 to 15° C. and is 
free from reducing impurities, in the proportion so that 13 g of iodine 
will be present in 1,000 cc of solution. Set aside a small portion of 
this solution while pure, and pass. dry chlorine into the remainder 
until the halogen content of the solution is doubled. Ordinarily it 
will be found that by passing the chlorine into the main part of the 
solution until the characteristic color of free iodine has just been dis- 
charged, there will be a slight excess of chlorine, which is corrected 
by the addition of the requisite amount of the unchlorinated portion, 
until all free chlorine has been destroyed. A slight excess of iodine 
does little or no harm, but excess of chlorine must be avoided. 

(g) Hatr Norma Sutpnuric Acip Sotution.—Add about 15 cc 
sulphuric acid (1.84 specific gravity) to distilled water, cool and 
dilute to 1,000 cc. Determine the exact strength by titrating against 
freshly Pe idatdized sodium hydroxide or by any other accurate 
method. Either adjust to exactly half normal strength or leave as 
originally made, applying appropriate correction. 


4. BASIS OF PURCHASE 


Material is to be purchased by weight or volume, as specified in 
the contract. When purchased by volume, 1 gallon of oil shall mean 
231 cubic inches at 15.5° C. 


8 CIRCULAR OF THE BUREAU OF STANDARDS 
VII. PACKING OF SHIPMENTS 


Packing shall be in accordance with commercial practice unless 
otherwise specified. | 
VIII. NOTES 


This specification supersedes that part of Federal Specifications 
Board specification No. 4 (Bureau of Standards Circular No. 82, 2d 
ed.), which covered boiled linseed oil. For specification for raw lin- 
seed oil-see Federal Specifications Board specification No. 4a (Bureau 
of Standards Circular No. 82, 3d ed.). The specification for refined 
linseed oil contained in F erarnt Specifications Board specification 
No. 4 (Bureau of Standards Circular No. 82, 2d ed.) is revoked. 

For formulas and methods of using this A Ir Hs and information 
regarding the use of other specification paint materials see Bureau 
of Standards Technologic Paper No. 274, entitled “Use of United 
States Government Specification Paints a Paint Materials.” 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 


6 CENTS PER COPY © 
Vv Vitruyitys 


U. S. Gov’t 
Master 
Specification 
No. 476 


DEPARTMENT OF COMMERCE 
BUREAU OF STANDARDS 


George K. Burgess, Director 


CIRCULAR OF THE BUREAU OF STANDARDS, No. 331 


[Issued April 29, 1927] 


e 


UNITED STATES GOVERNMENT MASTER SPECIFICATION FOR 
CHROME YELLOW (LEMON, MEDIUM, AND ORANGE; DRY, 
PASTE IN OIL, AND PASTE IN JAPAN) 


FEDERAL SPECIFICATIONS BOARD SPECIFICATION No. 476 


This specification was officially promulgated by the Federal Specifications 
Board on March 5, 1927, for the use of the departments and independent 
establishments of the Government in the purchase of chrome yellow (lemon, 
medium and orange; dry, paste in oil, and paste in japan). 


[The latest date on which the technical requirements of this specification shall become mandatory for all 
departments and independent establishments of the Government is June 6, 1927. They may be put into 
effect, however, at any earlier date after promulgation.] 


CONTENTS 


* Page 

I EATER UT i ee cede tm ee eee cds 2 
NEMS Ferre Je re ro fo oe oe eo ee Mee ee 2 
Mii iMasetialand workmanship 5... 4.ice0s_ lewis Jiu ul ue ate cul Z 
Dee seeere remiromente 6406. 284s die eis 56 es hele cn we 2 
lee ere POMOC OTS sn ee a ho io Se oe ir se ek a gen ots 2 
oI te aie dake, cath phates J pally Satis TS kai MRE a Mi eget 2 

ci ge ge SE IE RL RS lg « Slat sgety ofp tenia te Opie inert 2 

SEU GES 21 FREI ade emcarrictin nip ate is NSA SEES ae 3 

VI. -Metheds of sampling and testing-.---.--2222-222 ls scr c2 lee 3 
MIAO er sur Pee et i See eo Fee oF oes 3 

2. Laboratory examination, dry pigment__-_.._--2 _-_2-- 2. 4 

3. Laboratory examination, paste in oil_..._.......--------.. 5 

4. Laboratory examination, paste in japan__.______---___-_.- 8 
EEE gia 14. Seep apoeeyo-ae Ws (REY Raa BOO EL NAY 7 SO RPC UN ATA seep NE 9 

ae EMEC 8 SATIS NST Gerla ry rae nr era 10 
ERs SNe dos hte aided pelo ahce Ros 2 by eede bs Set d-SHteu eek 10 


43233°—27 


yi) CIRCULAR OF THE BUREAU OF STANDARDS 


I. GENERAL SPECIFICATIONS 
There are no general specifications applicable to this specification. 
II. GRADES 


This specification covers the grade of chrome yellow commonly 
known in the trade as “‘C. P.”” It covers a wide variety of lemon, 
medium, and orange yellows, both as dry pigments, as pastes in oil, 
and as pastes in japan. 


III. MATERIAL AND. WORKMANSHIP 
See detail requirements. 
IV. GENERAL ee 
See detail requirements. 
V. DETAIL REQUIREMENTS 


1. DRY PIGMENTS 


The dry pigments shall be chemical precipitates consisting of 
normal or basic lead chromates or mixtures of these with or without 
admixtures of other insoluble compounds of lead, but without any 
other admixtures, and shall conform to the following requirements: 


Maximum 

per cent 
Coarse particles (residue retained on No. 325 sieve).--.--------+----2--5 (10) 
‘Total matter soluble in water... ......2=.-.-2-46.+.++- osu ee eee oe: 
Total of all substances other than compounds of lead___.-.------------ 3. 0 
Organic colors or lakes__._.-_...-~-----enen-e2-~=nde eer anees See None. . 


The mass color and character of the tint shall be the same as and 
the tinting strength shall not be less than those of a sample mutually 
agreed upon by buyer and seller. 


2. PASTE IN OIL 


The paste color in oil shall consist of the pigment described kbitle 
ground to a paste in linseed oil. The paste as received shall not be 
caked in the container and shall break up readily in linseed oil to 
form a smooth paint of brushing consistency and shall conform to the 
following requirements: 


— 


3 


Maximum | Minimum 


Per cent Per cent 
Pinment . 02. ono calenccnaatacrehungs dapeineseuseecbineseneendesuh sane line 75 


 DiSrrssed OF enone nie occ nw iomeremnconnbdibee. Abt See ek ole Aen ee oe ES RY Rapes est 
Water and other volatile matter... 550... i. sd caus eta es aenee ee nenee eee 1 ER REN Lie 
Coarse particles and skins-(total residue retained on No. 325 sieve) ...----------- ok! Px « fp nets a 


The mass color and character of the tint shall be the same as and 
the tinting strength shall be not less than those of a sample mutually 
agreed upon by the buyer and seller. 


SPECIFICATION FOR CHROME YELLOW 3 


3. PASTE IN JAPAN 


The paste color in japan shall consist of the pigment described above 
thoroughly ground to a paste in high-grade grinding japan. The 
paste as received shall not be caked in the container and shall break 
up readily in turpentine to form a smooth paint of brushing con- 
sistency that will dry within’one hour to a hard, flat coat that can 
be varnished within five hours of time of application without streaking 
or bleeding. It shall also conform to the following requirements: 


Maximum | Minimum 


Percent Per cent 
70 


BoM we eee ae ek ed) sa I a os Bee GH D4 
Vehicle {containing not less than 40 per cent of nonvolatile matter)___......._.-_ 7 SR satan ES 


The mass color and character of the tint shall be the same as and 
the tinting strength shall be not less than those of a sample mutually 
agreed upon by the buyer and seller. 


VI. METHODS OF SAMPLING AND TESTING 


Deliveries wil, in general, be sampled and tested by the following 
methods, but the purchaser reserves the right to use any additional 
information to ascertain whether the material meets the specification. — 


1. SAMPLING 


It is mutually agreed by buyer and seller that a single package 
out of each lot of not more than 1,000 packages shall be taken as 
representative of the whole. 

With dry pigment, this package shall be opened by the inspector 
and a sample of not less than 1 pound taken at random from the 
contents. This shall be placed in a clean, dry metal or glass con- 
tainer closed with a tight cover, sealed, marked, and sent to the 
laboratory. With paste, whenever possible, an original unopened 
container shall be sent to the laboratory, and when this is for any 
reason not done, the inspector shall determine by thorough testing 
with a paddle or spatula whether the material meets the requirements 
regarding not caking in the container. See VI, 3, (a). Heshall then 
thoroughly mix the contents of the container and draw a sample of 
not less than 1 pound. This sample shall be placed in a clean, dry 
metal or glass container, which it must nearly fill. The container 
shall be closed with a tight cover, sealed, marked, and sent to the 
laboratory for test with the inspector’s report on caking. The in- 
spector should have a portion of the mutually agreed upon sample 
of the dry pigment, paste in oil, or paste in japan, as may be called 
for in the contract. Any delivery that is obviously different in color 
than the mutually agreed upon sample, or in case of paste that is 
badly caked in the container, shall be rejected by the inspector with- 
out sending a sample to the laboratory. | | 


4 CIRCULAR OF THE BUREAU OF STANDARDS 


When requested, a duplicate sample may be taken from the same 
package and delivered to the seller, and the inspector may take a 
third sample to hold for test in case of dispute. 


~ lal 


(2) Mass Cotor.—Weigh 1 g each*of sample and the mutually 
agreed upon standard and rub up separately on a glass plate or stone 
slab, using the same amount of the same linseed oil in each case. 
Rubbing up (mixing with oil) is best done with a muller and should 
be such that no lumps remain and each lot receives the same amount 
of rubbing. Place portions of each side by side on a clear strip of 
glass, turn the glass over and compare the colors. If there is a differ- 
ence in color the delivery does not meet the specification. 

(}) Cuaracter or Tint AND TinTING SrrencTH.— Weigh accu- 
rately on a counter-poised watch glass about 0.02 g of the sample 
and one hundred times as much dry zinc oxide and transfer to a 
large glass plate. Add 0.7 cc of clear raw linseed oil (measure from 
a burette) and mix with a clean steel (not nickel plated) spatula 
until the mass appears to be homogenous. Wipe off the spatula on 
the glass plate and on the rubbing surface of the glass muller. Grind 
the paste with a circular motion fifty times with the muller, using a 
uniform pressure. Gather up the paste with the spatula and grind 
again fifty times with the muller. Repeat the operation once more. 
Gather up the paste with the spatula and set aside. Using the stand- 
ard mutually agreed upon in place of the sample, duplicate the above 
procedure. Stir each of the pastes with clean spatulas and transfer 
portions to a microscope slide, quite close together and draw a spatula 
across both so as to make them meet in a line. Compare the colors 
on both sides of the glass. If the sample differs from the standard 
in tone; that is, if it shows more reddish yellow or a more greenish 
yellow than the standard it does not meet the specification in character 
of tint. If it shows the same character of tint and the rub out is as 
dark or darker than the standard, it meets the specification im tinting 
strength. If it shows the same character of tint and the rub out is 
lighter than the standard it does not meet the specification in tinting 
strength. ION 

(c) Coarse Particies.—Dry in an oven at 105 to 110° C., a No. 
325 sieve, cool, and weigh accurately. Weigh 10 g of the sample, 
transfer to a mortar, add 100 cc of water, thoroughly mix by gentle 
pressure with the finger to break up all the lumps, and wash through 
the sieve with a gentle stream of water, stirring gently with a camel’s 
hair brush until nothing more passes through the sieve. Dry the 
sieve at 105 to 110° C. for one hour, cool, and weigh. From the 
increase in weight of the sieve and the weight of sample calculate the 
percentage of coarse particles, 


2. LABORATORY EXAMINATION, DRY PIGMENT 


SPECIFICATION FOR CHROME YELLOW 5 


(d) Oreantc Cotors or Laxes.—Test the pigment successively 
with hot water, 95 per cent alcohol and chloroform. If the solutions 
should remain colorless, organic colors are probably absent, but if 
organic colors resistant to the above reagent are suspected, other 
tes ~may be applied and it may be necessary to follow methods 

ven in such books as Tests for Coal Tar Colors in Aniline Lake, 
py Zerr and Mayer; A Systematic Survey of Organic Coloring 
Matters, by Schultz and Julius; Identification of Pure Organic Com- 
pounds, by Mulliken. 

(¢) Marrer SotusLe In Water.—Transfer about 2.5 ¢ (accurately 
weighed) to a 250 cc graduated flask. Add 100 cc distilled water and 
boil for five minutes. Allow to cool, fill to mark with distilled water, 
mix thoroughly and allow to settle. Decant through a dry filter and 
discard the first 25 cc of filtrate. Transfer 100 cc of the remaining 
clear filtrate to a weighed dish, evaporate to dryness, heat for one hour 
at 105 to 110° C., cool, weigh, and compute percentage of matter 
soluble in water. 

(f) Water and OrHer VouaTiLeE Matrer.—Heat about 2 g, 
accurately weighed, in a tared dish or weighing bottle for three 
hours at 105 to 110° C., cool and weigh. Compute loss in weight 
as water and other volatile matter. 

(g) INsotusLE Marrer.—Treat an accurately weighed portion of 
about 1 g with 25 cc of concentrated hydrochloric acid and boil for 
from 5 to 10 minutes in a covered beaker, adding about 6 drops of 
alcohol, 1 at a time, to the boiling liquid. Dilute to 100 ce with hot 
water and boil for from 5 to 10 minutes. Filter the hot solution (if 
insoluble matter is present) and wash with boiling water till wash- 
ings are free from lead and chlorine. Ignite, weigh, and compute 
percentage of insoluble matter. 

(h) Oruer Impurities.—If careful qualitative analysis shows 
absence of all bases other than lead, as will generally be the case, no 
further examination will be necessary. If other bases are found, 
determine by appropriate methods.’ 

(i) CaucunaTIon or ToTaL oF ALL SussTaNces OTHER THAN 
Compounps or Leap.—Add together the percentages of matter 
soluble in water (VI, 2, (e)), water and other volatile matter (VI, 2, 
(f)), insoluble matter (VI, 2, (g)), and other impurities (VI, 2, (/)). 


3. LABORATORY EXAMINATION, PASTE IN OIL 


(a) Caxine In ContTarneR.—When an original package is received 
in the laboratory, it shall be weighed, opened, and stirred with a 
stiff spatula or paddle. The paste must be no more difficult to break 
up than a normal good grade of similar material. The paste shall 
finally be thoroughly mixed, removed from the container, and the 


1See A. S. T. M. standards D 126-23. 


7 
oe J 
6 CIRCULAR OF THE BUREAU OF STANDARDS 


container wiped clean and weighed. This weight subtracted from the 
weight of the original package gives the net weight of the contents, 
A portion of thoroughly mixed paste shall be placed in a clean con- 
tainer and the portions for the remaining tests promptly weighed 
out. 

(6) Cotor.—Place portions of the sample and of the standard 
mutually agreed upon side by side on a clean strip of glass. Turn 
the glass over and compare the colors. If there is a difference in 
color the delivery does not meet the specifications. 

(c) CHaracrrer oF Tint aND Tintine StrRENGTH.—Weigh accu- 
rately about 0.03 g of the thoroughly stirred paste (weighing by 
difference and recording exact weight). Transfer to a large glass 
plate. Add to this 100 times as much dry zine oxide (accurately 
weighed). Proceed as in VI, 2, (6). 

(d) CoaRsE PARTICLES AND Brennen —Dry in an oven at 105 to 110° 
a No. 325 sieve, cool, and weigh accurately. Weigh an amount of 
paste containing 10 g of pigment (see VI, 3, (g)), add 100 ce of kero- 
sene, mix thoroughly, and wash through the sieve using kerosene, 
but otherwise follow VI, 2, (c)). 

(¢) WATER AND Baden Vovatine Marrer. —Weigh accurately 
from 3 to 5 g of the paste into a tared flat-bottom dish about 8 cm 
in diameter, spreading the paste over the bottom, heat at 105 to 
110° C. for three hours, cool and weigh. 

(f) Mrxine witH Linsgep Orut.—Place 100 g of the ae in a 
cup. Add 50 cc raw linseed oil slowly with careful stirring and 
mix with a spatula or paddle. The resulting mixture must be smooth 
and of good brushing consistency. 

. (g) PERCENTAGE oF PigmentT.—Weigh accurately about 15 g of 
ins paste in a weighed centrifuge tube. Add 20 to 30 cc of “extrac- 
tion mixture’’ (see Reagents), mix thoroughly with a glass rod, wash 
the rod with more of the extraction mixture, and add enough of 
the reagent to make a total of 60 cc in the tube. Place the tube in 
the container of a centrifuge, surround with water, and counterbalance 
the container of the opposite arm with a similar tube or a tube with 
water. Whirl at a moderate speed until well settled. Decant the 
clear supernatant liquid, repeat the extraction three times with 40 
cc of extraction mixture. 

After drawing off the extraction itches det Be tube i in a banker 
of water at about 80° C. or on top of a warm oven for 10 minutes, 
then in an oven at 105 to 110° C. for two hours. Cool, weigh, and 
calculate the percentage of pigment. Grind the pigment to a fine 
powder, pass through a No. 80 sieve to remove any skins, and bee 
serve in a stoppered bottle. 

(h) Preparation or Farry Acips.—To about 25 g of the taal 
in a porcelain casserole, add 15 cc of aqueous sodium hydroxide (see 


SPECIFICATION FOR CHROME YELLOW 7 


Reagents, and 75 cc of ethyl alcohol, mix and heat uncovered on a 
steam bath until saponification is complete (about an hour). Add 
100 cc of water, boil, add sulphuric acid of specific gravity 1.2 (8 to 
10 ce in excess), boil, stir, and transfer to a separatory funnel to which 
some water has been previously added. Draw off as much as pos- 
sible of the acid aqueous layer, wash once with water, then add 50 
ec of water and 50 cc of ether. Shake very gently with a whirling 
action to dissolve the fatty acids in the ether, but not so violently 
as to form an emulsion. Draw off the acqueous layer and wash the 
ether layer with one 15 cc portion of water and then with 5 cc portions 
of water until free from sulphuric acid. Then draw off the water 
layer completely. Transfer the ether solution to a dry flask and 
add 25 to 50 g of anhydrous sodium sulphate. Stopper the flask 
and let stand with occasional shaking at a temperature below 25° 
C. until the water is completely removed from the ether solution, 
which will be shown by the solution becoming perfectly clear above 
the solid sulphate. Decant this clear solution, if necessary, through 
a dry filter paper into a dry 100 cc Erlenmeyer flask. Pass a rapid 
current of dry air (pass through a CaCl, tower) into the mouth of the 
Erlenmeyer flask and heat to a temperature below 75° C. on a dry, 
hot plate until the ether is entirely driven off. 

It 1s wnportant to follow all of the details, since ether generally con- 
tains alcohol, and after washing with water always contains-water. It 
is very difficult to remove water and alcohol by evaporation from fatty 
acids, but the washing of the ether solution and subsequent drying with 
anhydrous sodium sulphate removes both water and alcohol. Ether, in 
the absence of water and alcohol, is easily removed from fatty acids by 
gentle heat. 

The fatty acids prepared as above should be kept in a stoppered 
flask and examined at once. 

(() Test ror MINERAL OIL AND OTHER UNSAPONFIABLE MaTrEr.— 
Place 10 drops of the fatty acid (2) in a 50 cc test tube, add 5 cc of 
alcoholic soda (see Reagents) boil vigorously for five minutes, add 
40 cc of water, and mix; a clear solution indicates that not more than 
traces of unsaponifiable matter are present. If the solution is not 
clear, the oil is not pure linseed oul. 

(7) Iopins Numsper or Farry Acips.—Place a small quantity 
of the fatty acids (A) in a small weighing burette or beaker. Weigh 
accurately. Transfer by dropping from 0.09 to 0.15'g into a 500 cc 
bottle having a well-ground glass stopper, or an Erlenmeyer flask 
haying a specially flanged neck for the iodine test. Reweigh the 
burette or beaker and determine the amount of sample used. Add 


8 CIRGULAR OF THE BUREAU OF STANDARDS 


10 cc of chloroform. Whirl the bottle to dissolve the sample. Add 
10 cc chloroform to each of two empty bottles like that used for the 
sample. Add to each bottle 25 ce of the Wijs solution (see Reagents) 
and let stand with occasional shaking for one hour in a dark place at 
a temperature of from 21 to 23° C. Add 10 ce of the 15 per cent 
potassium iodide solution and 100 cc of water, and titrate with stand- 
ard sodium thiosulphate, using starch as indicator. The titrations 
on the two blank tests should agree within 0.1 cc. From the differ- 
ence between the average of the blank titrations and the titration on 
the sample and the iodine value of the thiosulphate solution, caleu- 
late the iodine number of the sample tested. (lodme number is 
centigrams of iodine to 1 g of sample.) If the iodine number is less 
than 175 the oil does not meet the specification. 

(c) EXAMINATION OF ExtTRacTED Pigmmnt.—Apply tests VI, 2, 
(d); VI, 2, (e); VI, 2, (g); V1, 2, (2); and VI, 2, (@). 


4, LABORATORY EXAMINATION, PASTE IN JAPAN 


(a) CaxInG IN ConTAINER.—Apply test VI, 3, (a). 

(6) Cotor.—Apply test VI, 3, (6). 

(c) Cuaracter or Tint and TintiInc Strenctu.—Make test in 
a manner similar to VI, 3, (c), except that on account of the volatile 
matter in japan pastes it is not easy to weigh exact amounts. For 
weighing, the materials should be placed in a wide-mouth stoppered 
weighing tube along with a short spatula or spoon. After weighing 
the whole, transfer with the spatula or spoon about 0.03 g to the 
glass plate, return spatula or spoon to weighing bottle, insert stopper, 
and again weigh. (To avoid trouble due to drying while weighing 
the zine oxide cover the paste with about half of the oil to be later 
used.) The difference in weight gives the weight of material taken. 
Then weigh one hundred times this weight of zine oxide and proceed 
as in VI, 2, (6). 

(d) Coarse Particues anp Sxins.—Follow method gives in 
V1; 35d 

(e) VouatiteE Marrer.—Follow method VI, 3, (e) with the sisi 

cautions regarding weight of sample given in VI, 4; (c). 
— (f) Mrxine wirn Turpentine anp Dryine Txsts.—Place <bot 
100 g of the paste in a cup and add turpentine slowly from a burette 
while thoroughly mixing with a spatula or paddle. The paste 
should readily break up and form a paint of brushing consistency. 
Note the volume of turpentine required. This will vary somewhat, 
but, in general, about 50 cc will suffice. Thoroughly stir this paint, 
strain through a No. 100 sieve and apply by brushing to a clean 
metal panel held in a vertical position. Apply the paint to only a 


SPECIFICATION FOR CHROME YELLOW 9 


part of the panel, leaving a margin of at least 2.5 cm (1 inch) of 
unpainted metal around the painted portion. It is best to use a 
camel’s-hair brush for this painting. Allow the panel to stand in a 
vertical position in a well-ventilated room at room temperature 
(70 to 90° F.) for 1 hour. The film should be flat, of extremely fine 
and smooth texture, uniform as regards color and finish and must be 
hard enough to stand light rapid rubbing with the finger without 
being removed. After a total of five hours drying, a brush coat of 
Damar varnish (Damar resin cut in turpentine) shall be applied over 
the entire surface of the panel. Any softening or raising of the flat 
coat or any separation of color by this varnishing operation is cause 
for rejection. In case of dispute on this drying test due to atmos- 
pheric conditions, and umpire tests are necessary such tests shall be 
made in a well-ventilated room maintained at a temperature of 70° F. 
and relative humidity of 65 per cent saturation. 

(g) Percentace or Picment.—Using the precautions in weighing 
sample given in VI, 4, (c) follow method given in VI, 3, (9). 

(hk) Examination oF Exrracrep Piement.—Apply tests VI, 2, 
(d); VI, 2, (e); VI, 2, (g); VI, 2, (2); and VI, 2, (@). 


5. REAGENTS 


(2) Extraction Mrxturs.— 

10 volumes ether (ethyl ether). 
6 volumes benzol. 

4 volumes methyl alcohol. 

1 volume acetone. 

(6) Aquzous Soptum Hyproxipr.—Dissolve 100 g of sodium 
hydroxide in distilled water and dilute to 300 cc. 

(c) Auconotic Sopium HypRroxIpDE Sotution.—Dissolve pure 
sodium hydroxide in 95 per cent ethyl alcohol in the proportion of 
about 22 g per 1,000 cc. Let stand in a stoppered bottle. Decant 
the clear liquid into another bottle and keep well. stoppered. This 
solution should be colorless or only slightly yellow when used, and it 
will keep colorless longer if the alcohol is previously treated with 
sodium hydroxide (about 80 g to 1,000 cc), kept at about 50° C. for 
15 days and then distilled. 

-(d) Porasstum lopIpE SotutTron.—Dissolve 150 g of potassium 
iodide free from iodate in distilled water and dilute to 1,000 ce. 

(e) Wiss Sotution.—The preparation of the iodine monochloride 
solution presents no great difficulty, but it should be done with care 
and accuracy in order to obtain satisfactory results. There shall be 
in the solution no sensible excess either of iodine or more particu- 
larly of chlorine over that required to form the monochloride. This 


10 CIRCULAR OF THE BUREAU OF STANDARDS 


condition is most satisfactorily attained by dissolving in the whole 
of the acetic acid to be used the requisite quantity of iodine, using 
gentle heat to assist the solution, if it is found necessary. Dissolve. 
iodine in glacial acetic acid that has a melting point of 14.7 to 15° C. 
and is free from reducing impurities in the proportion so that 13 ¢ 
of iodine will be present in 1,000 ce of solution. Set aside a small 
portion of this solution while pure, and pass dry chlorine into the 
remainder until the halogen content of the solution is doubled. 
Ordinarily it will be found that by passing the chlorine into the main’ 
part of the solution until the characteristic color of free iodine has 
just been discharged, there will be a slight excess of chlorine which is 
corrected by the addition of the requisite amount of the unchlorinated 
portion until all free chlorine has been destroyed. A slight excess of 
iodine does little or no harm, but excess of chlorine must be avoided, 

(f) Sranparp Sopium TuiosutpHate SoLtutTion.—Dissolve pure 
sodium thiosulphate in distilled water (that has been well boiled to 
free it from carbon dioxide) in the proportion of 24:83 g of erystal- 
lized sodium thiosulphate to 1,000 ce of the solution. It is best 
to let this solution stand for about two weeks before standardizing. 
Standardize with pure resublimed iodine.? This solution will be 
approximately decinormal, and it is best to leave it as it is after 
determining its exact iodine value, rather than to attempt to adjust 
it to exactly decinormal. Preserve in a stock bottle provided with 
a guard tube filled with soda lime. | 

(g) StarcH So.tution.—Stir up 3 g of potato starch or 5 g of 
soluble starch with 100 cc of 1 per cent salicylic acid solution, add 
300 to 400 cc of boiling water, and boil the mixture until the starch is 
practically dissolved, then dilute to 1 liter. 


VII. PACKING OF SHIPMENTS 


Packing shall be in accordance with commercial practice unless 


otherwise specified. 
VIII. NOTES 


There are very many different hues and shades that can with 
equal exactness be called chrome yellow. The selection of the one 
desired is entirely a matter of taste. There is no practical method 
of getting the color desired, except that of having it match in color, 
character of tint, and tinting strength the sample mutually agreed 
upon. The composition requirements of the specification are of only — 
secondary importance. 


1 Treadwell-Hall, Analytical Chem. 2, 6th ed. p. 551. 


SPECIFICATION FOR CHROME YELLOW 1] 


All purchasers and users of specification paint materials should 
consult Bureau of Standards Technologic Paper No. 274, entitled 
“Use of United States Government Specification Paints and Paint 
Materials.’’ Material covered by this specification is not discussed 


in that publication, but the information contained therein will 
nevertheless be of value. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
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AT 
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